Development of augmented reality serious games with a vibrotactile feedback jacket

Background: In the past few years, augmented reality (AR) has rapidly advanced and has been applied in different fields. One of the successful AR applications is the immersive and interactive serious games, which can be used for education and learning purposes. Methods: In this project, a prototype of an AR serious game is developed and demonstrated. Gamers utilize a head-mounted device and a vibrotactile feedback jacket to explore and interact with the AR serious game. Fourteen vibration actuators are embedded in the vibrotactile feedback jacket to generate immersive AR experience. These vibration actuators are triggered in accordance with the designed game scripts. Various vibration patterns and intensity levels are synthesized in different game scenes. This article presents the details of the entire software development of the AR serious game, including game scripts, game scenes with AR effects design, signal processing flow, behavior design, and communication configuration. Graphics computations are processed using the graphics processing unit in the system. Results /Conclusions: The performance of the AR serious game prototype is evaluated and analyzed. The computation loads and resource utilization of normal game scenes and heavy computation scenes are compared. With 14 vibration actuators placed at different body positions, various vibration patterns and intensity levels can be generated by the vibrotactile feedback jacket, providing different real-world feedback. The prototype of this AR serious game can be valuable in building large-scale AR or virtual reality educational and entertainment games. Possible future improvements of the proposed prototype are also discussed in this article

Controlled manipulation of oxygen vacancies using nanoscale flexoelectricity

Oxygen vacancies, especially their distribution, are directly coupled to the electromagnetic properties of oxides and related emergent functionalities that have implication in device applications. Here using a homoepitaxial strontium titanate thin film, we demonstrate a controlled manipulation of the oxygen vacancy distribution using the mechanical force from a scanning probe microscope tip. By combining Kelvin probe force microscopy imaging and phase-field simulations, we show that oxygen vacancies can move under a stress-gradient-induced depolarisation field. When tailored, this nanoscale flexoelectric effect enables a controlled spatial modulation. In motion, the scanning probe tip thereby deterministically reconfigures the spatial distribution of vacancies. The ability to locally manipulate oxygen vacancies on-demand provides a tool for the exploration of mesoscale quantum phenomena, and engineering multifunctional oxide devices.Comment: 35 pages, Main text and the supplementary information combine

Quantifying the grain boundary segregation strengthening induced by post-ECAP aging in an Al-5Cu alloy

Hardening on annealing (HOA) has been frequently observed in nanostructured metals and alloys. For nanostructured materials obtained by severe plastic deformation (SPD), HOA has been attributed to the reduction of dislocation sources within grains and grain boundary relaxation during annealing. In the present work, it is shown that when a bimodal grain structured (a mixture of micron-sized and ultrafine grains) Al-5Cu alloy prepared by equal channel angular pressing (ECAP) was subjected to post-ECAP natural and artificial aging treatments, the alloy shows a completely different precipitation behavior with an accelerated precipitation kinetics. No coherent θ'' or semi-coherent θ' precipitates form in the bulk of grains, while a large fraction of stable incoherent θ precipitates form along high angle boundaries. After artificial aging at low temperatures for a short time, a significant improvement of both ultimate tensile strength and uniform elongation was achieved without sacrificing the yield strength. A systematic microstructure characterization by EBSD, TEM and APT has been carried out to investigate the evolution of grain size, dislocation density and solid solution level of Cu as well as the precipitation of Al-Cu precipitates during natural and artificial aging treatments. A quantitative evaluation of different supposed strengthening mechanisms revealed that the segregation of Cu elements at grain boundaries plays a more important role than grain boundary relaxation and the dislocation source-limited strengthening to compensate the yield strength reduction caused by the decrease in dislocation density and solute content of Cu in solid solution.submittedVersio

Cryo-EM analysis of the post-fusion structure of the SARS-CoV spike glycoprotein

The spike (S) protein of coronaviruses is responsible for receptor recognition and the fusion between the viral membrane and the of cell host membrane. Here the authors report a cryo-EM structure of SARS-CoV post-fusion S2 trimer, providing insights into the fusion mechanism that could be useful for therapeutic development against coronaviruses

Microstructure and Its Effect on the Intergranular Corrosion Properties of 2024-T3 Aluminum Alloy

Intergranular corrosion is the main corrosion type of Al-Cu-Mg aluminum alloys, which seriously reduce the lifetime of aircraft structural parts. In this paper, the microstructure and the intergranular corrosion behavior of 2024 alloy with varying Cu and Mg content were studied by using a scanning electron microscope (SEM), transmission electron microscope (TEM), and three-dimensional atom probe (3DAP). The results show that nano-scale θ (Al2Cu) and S (Al2CuMg) particles precipitate along grain boundaries after quenching. The nano-cluster is the main strengthening phase in the 2024 alloy after natural aging for 96 h. The intergranular corrosion susceptibility is greatly affected by the presence of θ (Al2Cu) and S (Al2CuMg) phases along grain boundaries. Specifically, Cu-rich precipitates and intermetallics are known to act as local cathodes, which facilitates the action of oxygen reduction and ultimately drives anodic dissolution of the surrounding matrix material. The intergranular corrosion resistance of the alloy decreases with the increase in Cu and Mg contents. The alloy with a lower Mg content shows better corrosion resistance than the commonly used one with a Cu to Mg mass ratio of 2.9. The relationship between the observed corrosion behavior and various contents of Cu and Mg elements is discussed, which has potential to benefit the composition design of 2xxx aluminum alloy with high corrosion resistance

Microstructure and Its Effect on the Intergranular Corrosion Properties of 2024-T3 Aluminum Alloy

Intergranular corrosion is the main corrosion type of Al-Cu-Mg aluminum alloys, which seriously reduce the lifetime of aircraft structural parts. In this paper, the microstructure and the intergranular corrosion behavior of 2024 alloy with varying Cu and Mg content were studied by using a scanning electron microscope (SEM), transmission electron microscope (TEM), and three-dimensional atom probe (3DAP). The results show that nano-scale θ (Al2Cu) and S (Al2CuMg) particles precipitate along grain boundaries after quenching. The nano-cluster is the main strengthening phase in the 2024 alloy after natural aging for 96 h. The intergranular corrosion susceptibility is greatly affected by the presence of θ (Al2Cu) and S (Al2CuMg) phases along grain boundaries. Specifically, Cu-rich precipitates and intermetallics are known to act as local cathodes, which facilitates the action of oxygen reduction and ultimately drives anodic dissolution of the surrounding matrix material. The intergranular corrosion resistance of the alloy decreases with the increase in Cu and Mg contents. The alloy with a lower Mg content shows better corrosion resistance than the commonly used one with a Cu to Mg mass ratio of 2.9. The relationship between the observed corrosion behavior and various contents of Cu and Mg elements is discussed, which has potential to benefit the composition design of 2xxx aluminum alloy with high corrosion resistance

Geminin Orchestrates Somite Formation by Regulating Fgf8 and Notch Signaling

During somitogenesis, Fgf8 maintains the predifferentiation stage of presomitic mesoderm (PSM) cells and its retraction gives a cue for somite formation. Delta/Notch initiates the expression of oscillation genes in the tail bud and subsequently contributes to somite formation in a periodic way. Whether there exists a critical factor coordinating Fgf8 and Notch signaling pathways is largely unknown. Here, we demonstrate that the loss of function of geminin gave rise to narrower somites as a result of derepressed Fgf8 gradient in the PSM and tail bud. Furthermore, in geminin morphants, the somite boundary could not form properly but the oscillation of cyclic genes was normal, displaying the blurry somitic boundary and disturbed somite polarity along the AP axis. In mechanism, these manifestations were mediated by the disrupted association of the geminin/Brg1 complex with intron 3 of mib1. The latter interaction was found to positively regulate mib1 transcription, Notch activity, and sequential somite segmentation during somitogenesis. In addition, geminin was also shown to regulate the expression of deltaD in mib1-independent way. Collectively, our data for the first time demonstrate that geminin regulates Fgf8 and Notch signaling to regulate somite segmentation during somitogenesis