Search

Purpose To investigate the usefulness of three-dimensional (3D) printing in complex spinal surgery. Methods The study was conducted from October 2014 to March 2015 in Shenzhen Second Peoples' Hospital and 4 cases of complex severe spinal disorders were selected from our department. Among them one patient combined with congenital scoliosis, one with atlas neoplasm, one with atlantoaxial dislocation, and the rest one with atlantoaxial fracture-dislocation. The data of the diseased region was collected from computerized tomography scans for 3D digital reconstruction and rapid prototyping to prepare photosensitive resin models, which were applied in the treatment of these cases. Results The use of 3D models reduced operating time and intraoperative blood loss as well as the risk of postoperative complications. Furthermore, no pedicle penetrations or screw misplacement occurred according to the postoperative planar radiographic images. Conclusion The tactile models from 3D printing allow direct observation and measurement, helping the orthopedists to have accurate morphometric information to provide personalized surgical planning and better communication with the patient and coworkers. Moreover, the photosensitive resin models can also guide the actual surgery with the drilling of pedicle screws and safe resection of tumor.

The surface hydroxyl groups in TiO2 are crucial to many of its practical applications, but their controlled synthesis represents still a challenge. Herein, nanostructured TiO2 with rich surface hydroxyl species groups and high crystallinity (TiO2-OH) by high-temperature calcination have been developed by using the ionic liquid. Experimental measurements and theoretical calculations show a strong surface hydroxyl signal of two-dimensional 1H TQ-SQ MAS NMR, as well as clear changes of the charge density of TiO2 with the rich surface hydroxyl species. Moreover, the rich surface hydroxyl species groups in TiO2 not only significantly enhance its performances involving photogenerated current, photocatalysis and energy strorage but also show a bright future on marine applications because of its high activity and stability in simulation seawater. The characteristics and mechanism have been proposed to clarify the generation of surface hydroxyl species of TiO2 and the correponding directed hole-trapping at an atomic-/nanoscale.

Hierarchical structured mesoporous Co3O4/SiO2 composites have been fabricated by the in-situ transformation of cobalt nanocrystals in the mesoporous silica. The hierarchical porous composites show good structural stability during the thermal treating process and demonstrate high crystallinity after phase transformation. The highly crystalline Co3O4/SiO2 composite has uniform mesopores and exhibits good adsorption ability. This method offers a promising way to the design of hierarchical structured mesoporous materials with highly crystalline framework.

A finite element algorithm based on characteristic based split (CBS) scheme, in combination with arbitrary Lagrangian-Eulerian (ALE) framework, is presented to deal with numerical oscillation and mesh moving, and the complicated flow patterns are given, as studying the flow around oscillating circular cylinders, which are the typical fluid-structure interaction and encountered frequently in the engineering. Following this method, the two-dimensional incompressible Navier-Stokes equations (NSEs) are derived under the ALE reference frame, and consequently the CBS scheme in ALE configuration is given to approach the NSEs in some details. After such transformation, the convective terms can be removed from the original NSEs and the resulting equations become simple diffusion equations, which can be efficiently approached by the standard finite element method. Then, the finite element method is applied to the governing equations obtained, with the aid of an improved moving mesh technique implemented by the modified spring analogy to deal with the coupling between fluid and structure surfaces. Finally, some numerical examples related to flows around stationary and oscillating circular cylinders are simulated with the presented method, in comparison with existing numerical and experimental results. Additionally, the flow patterns of the oscillating cylinder wake are analyzed tentatively to study the evolution of unsteady vortices, which can induce the oscillation of the structures. The results show that the presented algorithm is feasible and efficient for flow around moving bodies, which includes two main typical problems, namely, the numerical oscillation and mesh moving.