A c c e p t e d M a n u s c r i p t Highlights (for review) -The dynamics of UV-induced oxygen vacancy is studied from the change of surface resistance.-The formation of 2DEG at the insulating surface of SrTiO 3 is confirmed by ARPES.-The UV-induced change in resistance responds differently to oxygen/gas exposure.-The behavior of resistance recovery suggests an alternative method of low-pressure sensing.Page 2 of 5 A c c e p t e d M a n u s c r i p t The effect of ultra-violet (UV) irradiation on the electronic structure and the surface resistance of an insulating SrTiO3(001) crystal is studied in this work. Upon UV irradiation, we shows that the two-dimensional electron gas (2DEG) emerges at the insulating SrTiO3 surface and there is a pronounced change in the surface resistance. By combining the observations of the change in valance band and the resistance change under different environments of gas pressure and gas species, we find that UV-induced oxygen vacancies at the surface plays a major role in the resistance change. The dynamic of the resistance change at different oxygen pressures also suggests an alternative method of low-pressure sensing.

Microfluidics is proposed as a technique for efficient sperm sorting, to achieve the ultimate goal of resolving infertility problems in livestock industry. Our study aimed to design a microfluidic sperm-sorting device (SSD) through a high-efficacy and cost- and time-effective fabrication process, by using COMSOL Multiphysics simulation and modeling software, and the design of experiment (DOE) method. The eight factors affecting SSD performance were established. The simulation was then run, and statistically significant factors were analyzed. Minitab16 was used to optimize the design modulus factor. By setting the statistical significance at p < 0.05, the factors affecting experimental structure were analyzed. At a desirability of 97.99, the optimal parameters for the microfluidic chip were: angle between sperm and medium inlet chambers (A = 43°), sperm inlet flow rate (B = 0.24 µL min−1), medium inlet flow rate (C = 0.34 µL min−1), and inlet and outlet chamber lengths (D = 5000 µm). These optima were then applied to microfluidics device construction. The device was produced using soft lithographic microfabrication techniques and tested on Holstein–Friesian bull sperm. The highest bull sperm-sorting performance for this microfluidic device prototype was 96%. The error between the simulation and the actual microfluidic device was 2.72%. Fluid viscosity ranges analysis-based simulations revealed acceptable fluid viscosity tolerances for the SSD. The simulation results revealed that the acceptable tolerance range for fluid viscosity was 0.00001–0.003 kg m−1 s−1. This optimally designed microfluidic chip-based SSD may be integrated into sperm x/y separation micro devices.

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Morphological transformations in primitive organisms have long been observed; however, its biomechanical roles are largely unexplored. In this study, we investigate the structural advantages of dimorphism in Arthrospira platensis, a filamentous multicellular cyanobacterium. We report that helical trichomes, the default shape, have a higher persistence length (Lp), indicating a higher resistance to bending or a large value of flexural rigidity (kf), the product of the local cell stiffness (E) and the moment of inertia of the trichomes’ cross-section (I). Through Atomic Force Microscopy (AFM), we determined that the E of straight and helical trichomes were the same. In contrast, our computational model shows that I is greatly dependent on helical radii, implying that trichome morphology is the major contributor to kf variation. According to our estimation, increasing the helical radii alone can increase kf by 2 orders of magnitude. We also observe that straight trichomes have improved gliding ability, due to its structure and lower kf. Our study shows that dimorphism provides mechanical adjustability to the organism and may allow it to thrive in different environmental conditions. The higher kf provides helical trichomes a better nutrient uptake through advection in aquatic environments. On the other hand, the lower kf improves the gliding ability of straight trichomes in aquatic environments, enabling it to chemotactically relocate to more favorable territories when it encounters certain environmental stresses. When more optimal conditions are encountered, straight trichomes can revert to their original helical form. Our study is one of the first to highlight the biomechanical role of an overall-shape transformation in cyanobacteria.

This paper presents development of a thin film aluminum microheater and a nickel temperature sensor for low temperature applications by using Micro-Electro-Mechanical Systems. Both of them are fabricated onto a glass substrate and protected by thin PDMS membrane. The micro heater is energized to find sensor characteristic. As linearity and accuracy of nickel sensor give a wide temperature range, its electrical resistance variations are calibrated directly by temperatures of energized microheater. Variations of resistance signal are transformed and fed back to control temperature of micro heater in PI closed-loop feedback control. Kp and Ki values are adj ustedto obtain the optimal time response. Experimental testing of controlled temperature ranges from 40°C to 140°C is presented for their integration in stability system.