The design of materials meeting the rigorous requirements of photocatalytic water splitting is still a challenge. Anisotropic Janus 2D materials exhibit great potential due to outstandingly high photocatalytic efficiency. Unfortunately, these materials are scarce. By means of ab initio swarm-intelligence search calculations, we identify a SiP 2 monolayer with Janus structure (i.e., out-of-plane asymmetry). The material turns out to be semiconducting with an indirect band gap of 2.39 eV enclosing the redox potentials of water. Notably, the oxygen and hydrogen evolution half reactions can happen simultaneously at the Si and P atoms, respectively, driven merely by the radiation-induced electrons and holes. The carrier mobility is found to be anisotropic and high, up to 10 –4 cm 2 V –1 s –1 , facilitating fast transport of the photogenerated carriers. The SiP 2 monolayer shows remarkably strong optical absorption in the visible-to-ultraviolet range of the solar spectrum, ensuring efficient utilization of the solar energy.

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The results showed that bi-cortical implant in sinus area increased the stability of the implant, especially for immediately loading implantation. The thickness of both crestal cortical bone and sinus floor cortical bone influenced implant micromotion and stress distribution; however, crestal cortical bone may be more important than sinus floor cortical bone.

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The aim of the present study was to evaluate the effect of the association between the implant apex and the sinus floor in posterior maxilla dental implantation by means of three-dimensional (3D) finite element (FE) analysis. Ten 3D FE models of a posterior maxillary region with a sinus membrane and different heights of alveolar ridge with different thicknesses of sinus floor cortical bone were constructed according to anatomical data of the sinus area. Six models were constructed with the same thickness of crestal cortical bone and a 1-mm thick sinus floor cortical bone, but differing heights of alveolar ridge (between 10 and 14 mm). The four models of the second group were similar (11-mm-high alveolar ridge and 1-mm-thick crestal cortical bone) but with a changing thickness of sinus floor cortical bone (between 0.5 and 2.0 mm). The standard implant model based on the Nobel Biocare® implant system was created by computer-aided design (CAD) software and assembled into the models. The materials were assumed to be isotropic and linearly elastic. An inclined force of 129 N was applied. The maximum von Mises stress, stress distribution, implant displacement and resonance frequencies were calculated using CAD software. The von Mises stress was concentrated on the surface of the crestal cortical bone around the implant neck with the exception of that for the bicortical implantation. For immediate loading, when the implant apex broke into or through the sinus cortical bone, the maximum displacements of the implant, particularly at the implant apex, were smaller than those in the other groups. With increasing depth of the implant apex in the sinus floor cortical bone, the maximum displacements decreased and the implant axial resonance frequencies presented a linear upward tendency, but buccolingual resonance frequencies were hardly affected. This FE study on the association between implant apex and sinus floor showed that having the implant apex in contact with, piercing or breaking through the sinus floor cortical bone benefited the implant stability, particularly for immediate loading.

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For maxillary sinus augmentation without grafting material implant technique, the stress of different tissues and the displacement of the implant were not increased much when the height of alveolar ridge is more than 7 mm. But if the alveolar bone height is less than 4 mm, this implant technique is not suggested. Immediately loading is not suggested and the loading opportunity should be after the stiff callus stage at least to improve the success rate.