Finite element analysis and clinical application of 3D-printed Ti alloy implant for the reconstruction of mandibular defects.

BACKGROUND: The reconstruction of segmental defect of the mandible has always been a challenge. The customized reconstruction plate without a bone graft is also considered a transitional means of rehabilitation and reconstruction in some cases. METHODS: This study evaluated the biomechanical behaviors of customized plates with different structural designs comparing with commercial plates using the finite element method in reconstrution of the lateral mandible defect. RESULTS: Simulations revealed the stress state in the plate bodies, bone tissues and screws were associated with the width, height, thickness of the plates as well as the distribution of screws. In all of the groups, the system of 16 mm-high, 2.8 mm-thick customized reconstruction plate with 10 screws was considered to be the most ideal design because of the most harmonious biomechanical state. What's more, the stress shielding effects were not obvious in this experiment. Based on the above findings, we conducted a clinical case analysis to verify the mechanical properties of customized reconstruction and obtained a satisfactory operation result. CONCLUSIONS: The results show that by adjusting the contour parameters of the reconstruction plates, an ideal and reliable customized plate can be manufactured. And the customized 3D-printed Ti alloy implant will be a new way to achieve mandibular reconstruction in patients unable to perform autologous bone graft surgery. TRIAL REGISTRATION: The present trial has been registered with ChiCTR, the registration number is ChiCTR 2,000,038,973 on 11/10/2020.

Continuously adjustable period optical grating based on flexoelectric effect of a bent-core nematic liquid crystal in planar cells.

The structures of flexodomains, which are similar to optical gratings and can be controlled by the amplitude of applied voltage and temperature, were verified through polarizing microscopy and light diffraction techniques. The properties of the optical grating induced by a bent-core nematic liquid crystal in planar cells with varied cell gaps and pretilt angles were studied. The period of optical grating decreases with the increase in the amplitude of the applied voltage and pretilt angle. In addition, the period increases with the increase in cell gap and temperature. The period of optical grating has a linear relationship with temperature. The continuously adjustable period has the potential to become an important and extended application of optical grating.

Activation of STAT6 by intranasal allergens correlated with the development of eosinophilic chronic rhinosinusitis in a mouse model.

Eosinophilic chronic rhinosinusitis (ECRS) is a chronic inflammatory disease characterized by prominent eosinophilic infiltration along with a T-helper-2 (Th2) response. It has been well documented that signal transducer and activator of transcription 6 (STAT6) is a nuclear transcription factor that mediates Th2-type immunity and is implicatory of STAT1 and STAT3 in the pathogenesis of allergic airway diseases. However, little is known about the association between STATs and ECRS. Here, we explored the relationship between STAT1, STAT3, and/or STAT6 and eosinophilic inflammation accompanied by Th2-type immunity in a mouse model of ECRS. An ovalbumin (OVA)-staphylococcal enterotoxin B (SEB)-induced ECRS murine model was first established. The mucosal histological alterations were determined using hematoxylin and eosin staining. The number of eosinophils in peripheral blood was measured using a blood cell analyzer. The cytokine (IL-4, IL-5, IL17 A and IFN-γ) expression levels in the sinonasal mucosa and total and OVA-specific IgE from serum were measured using ELISA. Then, the protein levels of STAT1, STAT3, STAT6, phosphorylated STAT1 (p-STAT1), p-STAT3, p-STAT6, T-box expressed in T-cells (T-bet), GATA binding protein 3 (GATA-3), and retinoic acid receptor-related orphan receptor γ (RORγt) in the sinonasal mucosa were examined by immunohistochemical staining or Western blotting. Local administration of OVA combined with SEB (OVA + SEB) induced multiple polyp-like lesions, accompanied by prominent eosinophilic infiltration in the sinonasal mucosa. The OVA- and OVA+SEB-treated groups showed significantly higher eosinophil counts from peripheral blood and total and OVA-specific IgE levels from serum than those in the PBS- and SEB-treated groups. The levels of p-STAT6 were markedly increased by OVA + SEB exposure, as well as GATA-3, IL-4, and IL-5, but did not affect STAT6, p-STAT1, p-STAT3, T-bet, RORγt, IFN-γ, or IL-17A. Furthermore, an eosinophil count in the sinonasal mucosa showed a positive correlation with the level of p-STAT6 in the ECRS mouse model. Signal transducer and activator of transcription 6 signaling could be activated in the OVA+SEB-induced ECRS model and might be a crucial signal transducer in the development of Th2-skewed ECRS.

A study on biosafety of HAP ceramic prepared by SLA-3D printing technology directly.

Hydroxyapatite powder was mixed into photosensitive resin to form complex shape scaffold using SLA-3D printing technology, and then the final entity was obtained successively by debinding and sintering. It is crucial to confirm whether the prepared hydroxyapatite scaffold have the toxic effects after our designed printing, debinding, and sintering processes because the photosensitive resin in the starting printing paste is poisonous to cells. To investigate these issues in details, thermogravimetric analysis (TG), differential scanning calorimetry (DSC), in vitro cytotoxicity test, and implantation pre-experiment in the rabbit parietal were performed, aiming to develop the SLA-3D prepared hydroxyapatite scaffold. Through thermal analysis, it was proved that photosensitive resin would be completely pyrolyzed at temperature ranging from 350 °C to 580 °C, corresponding to a secondary chemical reaction mechanism. Combined with cytotoxicity test results, it is unquestionable that the toxic substances would be totally decomposed after debinding process and a good biocompatible HAP samples could be obtained. The finally prepared HAP samples with micro-holes showed good biosafety in pre-experiment of the rabbit parietal implantation.

Enhancement of Image Quality in LCD by Doping γ-Fe2O3 Nanoparticles and Reducing Friction Torque Difference.

Improving image sticking in liquid crystal display (LCD) has attracted tremendous interest because of its potential to enhance the quality of the display image. Here, we proposed a method to evaluate the residual direct current (DC) voltage by varying liquid crystal (LC) cell capacitance under the combined action of alternating current (AC) and DC signals. This method was then used to study the improvement of image sticking by doping γ-Fe2O3 nanoparticles into LC materials and adjusting the friction torque difference of the upper and lower substrates. Detailed analysis and comparison of residual characteristics for LC materials with different doping concentrations revealed that the LC material, added with 0.02 wt% γ-Fe2O3 nanoparticles, can absorb the majority of free ions stably, thereby reducing the residual DC voltage and extending the time to reach the saturated state. The physical properties of the LC materials were enhanced by the addition of a small amount of nanoparticles and the response time of doping 0.02 wt% γ-Fe2O3 nanoparticles was about 10% faster than that of pure LC. Furthermore, the lower absolute value of the friction torque difference between the upper and lower substrates contributed to the reduction of the residual DC voltage induced by ion adsorption in the LC cell under the same conditions. To promote the image quality of different display frames in the switching process, we added small amounts of the nanoparticles to the LC materials and controlled friction technology accurately to ensure the same torque. Both approaches were proven to be highly feasible.

Improvement of Image Sticking in Liquid Crystal Display Doped with γ-Fe2O3 Nanoparticles.

Image sticking in thin film transistor-liquid crystal displays (TFT-LCD) is related to the dielectric property of liquid crystal (LC) material. Low threshold value TFT LC materials have a weak stability and the free ions in them will be increased because of their own decomposition. In this study, the property of TFT LC material MAT-09-1284 doped with γ-Fe2O3 nanoparticles was investigated. The capacitances of parallel-aligned nematic LC cells and vertically aligned nematic LC cells with different doping concentrations were measured at different temperatures and frequencies. The dielectric constants perpendicular and parallel to long axis of the LC molecules ε⊥ and ε//, as well as the dielectric anisotropy Δε, were obtained. The dynamic responses and the direct current threshold voltages in parallel-aligned nematic LC cells for different doping concentrations were also measured. Although the dielectric anisotropy Δε decreased gradually with increasing temperature and frequency at the certain frequency and temperature in LC state for each concentration, the doping concentration of γ-Fe2O3 nanoparticles less than or equal to 0.145 wt % should be selected for maintaining dynamic response and decreasing free ions. This study has some guiding significance for improving the image sticking in TFT-LCD.