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Abstract 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.

This study designs a differential dual-drive micro-feed mechanism, superposing the two “macro feed motions” (“motor drive screw” and “motor drive nut”) using the same transmission of “the nut rotary ball screw pair” structure. These two motions are almost equal in terms of speed and turning direction, thus the “micro feed” can be obtained. (1) Background: Thermal deformation is the primary factor that can restrict the high-precision micro-feed mechanism and the distribution of heat sources differs from that of the conventional screw single-drive system owing to the structure and motion features of the transmission components. (2) Discussion: This study explores the thermal field distribution and thermal deformation of the differentially driven micro-feed mechanism when two driving motors are combined at different speeds. (3) Methods: Based on the theory of heat transfer, the differential dual-drive system can be used as the research object. The thermal equilibrium equations of the micro-feed transmission system are established using the thermal resistance network method, and a thermal field distribution model is obtained. (4) Results: Combined with the mechanism of thermal deformation theory, the established thermal field model is used to predict the axial thermal deformation of the differential dual-drive ball screw. (5) Conclusions: Under the dual-drive condition, the steady-state thermal error of the nut-rotating ball screw transmission mechanism increases with the increase in nut speed and composite speed and is greater than the steady-state thermal error under the single screw drive condition. After reaching the thermal steady state, the measured thermal elongation at the end of the screw in the experiment is approximately 10.5 μm and the simulation result is 11.98 μm. The experimental measurement result demonstrates the accuracy of the theoretical analysis model for thermal error at the end of the screw.

In the field of bone tissue engineering, porous hydroxyapatite (HA) bone repair scaffolds with controlled architecture and porosity are challenging to manufacture and lack sufficient osteoinductive activity, which limit its wider clinical application. This study fabricated porous graphene oxide (GO)/HA composite ceramic scaffolds using digital light processing (DLP) technology. The properties of the composite ceramic slurry and the process parameters of curing, degreasing, and sintering were initially examined to ensure molding accuracy. The research showed that a small amount of GO (0.1–0.4 wt%) could better maintain the pore structure and improve the mechanical properties of composite ceramics. Porous scaffolds with pore sizes of 300–400 μm were prepared for co-culture with rat bone marrow mesenchymal stem cells to detect biocompatibility. The results showed that all scaffolds have no cytotoxicity. Compared with HA, the GO/HA ceramic scaffold significantly promoted the cell adhesion, proliferation, and expression of osteogenesis-related genes; GO (0.1–0.2 wt%) /HA scaffolds exhibited superior alkaline phosphatase activity and more effective bone mineralization, showing enhanced osteoinductivity. The porous GO/HA composite scaffold fabricated by DLP presented a strong potential for repairing bone defects.

Iron molten air batteries are a promising technology for clean and efficient electrical power generation, but their durability is a key challenge to commercialization. Here, we replaced LiCl in the KCl-LiCl-LiOH system with Li2SO4 or Li0.87Na0.63K0.50CO3 to investigate electrode corrosion and improve cycle life. The nickel air electrode exhibited low corrosion rate in KCl-Li2SO4-LiOH, but the kinetics of the air electrode reactions was impaired. Electrolyte composition influences pitting corrosion of the Ni air electrode in KCl-LiCl-LiOH and intercrystalline corrosion in KCl-Li2SO4-LiOH. KCl-LiNaKCO3-LiOH is a superior electrolyte for these iron air batteries with nickel air electrode. A tenacious, compact Li nickel oxide nano-scale particle layer on the nickel air surface in KCl-LiNaKCO3-LiOH retards nickel fin matrix (current collector) corrosion allowing long-term use. The air electrode surface is an electrocatalytic layer of uniform nano-particles. The iron molten air battery cycled for 850 cycles with an average coulombic efficiency of 88.6% and average discharge potential of∼1.04 V, achieving a ten-fold increase in cycle life in contrast with the previous result using KCl-LiCl-LiOH. This study explores key factors improving the Ni air electrode and cycle life without interfering with the cycling performance of the iron molten air battery. [ABSTRACT FROM AUTHOR]

Objective To understand the current situation of aluminum pollution in the main foods in Inner Mongolia and to evaluate the risk of dietary aluminum exposure of local residents. Methods The aluminum residues of foods containing aluminum additives in food safety risk monitoring in Inner Mongolia from 2010 to 2018 were analyzed. Combined with the food consumption data of residents in Inner Mongolia in 2012, the dietary aluminum intake and health risk was calculated and assessed by sex-age group. Results In this assessment, there were 1 083 common aluminum-containing foods samples with a detection rate of 69.44%(752/1 083). The average content of aluminum residue was 142.81 mg/kg, ranging from 0.30 mg/kg to 2 950.00 mg/kg. The average weekly intake of dietary aluminum for the whole population was 0.692 mg/kg BW which was lower than the tolerable weekly intake(PTWI, 2 mg/kg BW) formulated by the Joint Expert Committee on Food Additives(JECFA). The weekly intake of dietary aluminum for people with high food consumption was 4.868 mg/kg BW. It was 2.43 times that of PTWI. The average weekly dietary aluminum intake of people in different gender-age groups did not exceed PTWI, and the average intake decreased with the increase of age. Conclusion Aluminum containing additives in vermicelli and deep-fried dough sticks exceeded the standard seriously. Aluminum containing additives in puffed food and fermented flour products were used beyond the scope. High-consumption groups of all sex-age groups are at greater risk of aluminum exposure. Relevant departments need to strengthen the supervision of the abuse of aluminum-containing additives.

Iron molten air batteries are an attractive technology for electrical energy storage because of advantages of higher capacity, low cost, sustainability, and environmental friendliness compared to existing secondary batteries; however, battery applications still suffer from low coulombic efficiency and poor cycle stability. Here we report design of a robust fin air electrode for the iron molten air battery. The battery cycled stably at 500°C for 80 cycles with an average discharge potential of ∼1.04 V and average charging potential of ∼1.20 V. The highest coulombic efficiency reaches 93.4% to a 0.7 V discharge cutoff. The encouraging performance offers hope to design more advanced air electrodes for iron molten air batteries. [ABSTRACT FROM AUTHOR]

Cylindrical microlens array (CMA) is applied widely in imaging, sensing, and laser machining fields. Among the many techniques for machining CMA, moulding is considered a mass-production method with low-cost and good accuracy. Aimed at the present problems in the machining of CMA moulds, which include low processing efficiency and the prediction of the surface topography, this paper focused on the fabrication of CMA on RB-SiC moulds by precision grinding with micro-abrasive water jet (MAWJ) textured diamond wheels. The combined rough–fine grinding strategy for ceramic mould materials was proposed. The grinding experiments of CMA were carried out. The ultra-precision grinding method was optimized to obtain high shape accuracy and a high-quality surface of RB-SiC moulds. It was found that by using MAWJ-textured diamond wheels, the profile error in the peak-to-valley value (PV) of the CMA moulds can be further reduced to 6.7 μm by using the combined rough–fine strategy grinding process.

Adding a chiral dopant in twisted nematic (TN) liquid crystal cell can stabilize the orientation of liquid crystal molecules, particularly in high TN (HTN) or super TN (STN) liquid crystal cells. The difference in pitches in liquid crystal is induced by the chiral dopant, and these different pitches affect the orientation of liquid crystal director under an external applied voltage and influence the characteristics of microwave modulation. To illustrate this point, the microwave phase shift per unit length (MPSL) versus voltage is calculated on the basis of the elastic theory of liquid crystal and the finite-difference iterative method. Enhancing the pitch induced by the chiral dopant in liquid crystal increases the MPSLs, but the stability of the twisted structures is decreased. Thus, appropriate pitches of 100d, 4d, and 2d can be applied in TN, HTN, and STN cells with cell gap d to enhance the characteristics of microwave modulation and stabilize the structures in twisted cell. This method can improve the characteristics of liquid crystal microwave modulators such that the operating voltage and the size of such phase shifters can be decreased.

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.

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.

The microwave modulation induced by liquid crystal is decided by the liquid crystal director distribution under an external applied voltage. The rubbing-alignment of substrate has an effect on the liquid crystal director, which must result in the change of microwave phase-shift. To illustrate the influence of rubbing-alignment on the microwave phase-shift, the microwave modulation property of twisted nematic liquid crystal is researched adopting the elastic theory of liquid crystal and the finite-difference iterative method. The variations of microwave phase-shift per unit-length for different pre-tilt and pre-twist angles of liquid crystal on the substrate surface and anchoring energy strengths with the applied voltage are numerically simulated. The result indicates that with the increase of pre-tilt angle and with the decrease of anchoring energy strength the weak anchoring twisted cell with pre-twisted angle 90° relative to the strong anchoring non-twisted cell can increase the microwave phase-shift per unit-length. As a result, for achieving the maximum microwave modulation, the weak anchoring twisted cell with pre-tilt angle 5° and anchoring energy strength 1×10−5J/m2 should be selected, which provides a reliably theoretical foundation for the design of liquid crystal microwave modulator.