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Objective: We aimed to evaluate changes in the zygomatic pillar during orthodontic treatment involving premolar extraction, analyze the effects of maxillary first molar movement on zygomatic pillar remodeling, and examine occlusal characteristics and stress distribution after remodeling. Methods: Twenty-five patients who underwent premolar extraction were included in the study. The zygomatic pillar measurement range was defined, and cross-sectional areas, surface landmark coordinates, alveolar and cortical bone thicknesses, and density changes were assessed using Mimics software based on the cone-beam computed tomography scans taken before (T0) and after the treatment (T1). Multiple linear regression analysis was performed to determine the correlation between changes in the zygomatic pillar and maxillary first molar three-dimensional (3D) movement and rotation. Additionally, the correlation between pillar remodeling and occlusal characteristics was analyzed by Teetester. Pre- and post-reconstruction 3D finite element models were constructed and loaded with an average occlusal force of two periods. Results: The morphological and structural remodeling of the zygomatic pillar after orthodontic treatment involving premolar extraction showed a decreased cross-sectional area of the lower segment of the zygomatic pillar. The zygomatic process point moved inward and backward, whereas the zygomatico-maxillary suture point moved backward. The thicknesses of the zygomatic pillar alveolar and cortical bones were thinner, and reduced alveolar bone density was observed. Simultaneously, the movement and angle change of the maxillary first molar could predict zygomatic pillar reconstruction to a certain extent. With decreasing the total occlusal force and the occlusal force of the first molar, occlusal force distribution was more uniform. With zygomatic pillar remodeling, occlusal stress distribution in the zygomatic alveolar ridge decreased, and occlusal stress was concentrated at the junction of the vertical and horizontal parts of the zygomatic bone and the posterior part of the zygomatic arch. Conclusions: Orthodontic treatment involving premolar extraction led to zygomatic pillar remodeling, making it more fragile than before and reducing the occlusal force of the maxillary first molar and the entire dentition with stress concentrated in weak areas. Clinical relevance: No other study has focused on the effects of orthodontics on pillar structures. The present study indicates that the mesial movement of the maxillary first molar weakened the zygomatic pillar and reduced occlusal function, thereby providing insights for inserting anchorage screws and facial esthetics. [ABSTRACT FROM AUTHOR]

Recently, alcohols have attracted more attention due to their excellent tribological performance, especially superlubricity under low loads. Alcohol solution, as a liquid lubricant, can easily reach the superlubricity state under low loads because of the formed low shear hydroxylation interfaces induced by the tribochemical reactions. A general picture and its influencing factors have been elucidated, not only at the macroscopic scale but also at the nanoscale, which is sufficient to provide effective guidance for lubrication design and tribology research in engineering. Herein, we provide a review on the recent applications of alcohols in lubrication. In addition, the material transformation caused by alcohols in friction is a key factor affecting the tribological properties. As an important two-dimensional material, the growth mechanisms of graphene are variable, and the most famous is the formation of carbon radicals under the action of metal catalysts. Thus, based on the formation mechanism of carbon friction film (such as amorphous carbon and graphene), the main content of this review also includes the transformation of graphene in alcohol solution friction process. [ABSTRACT FROM AUTHOR]

The corrosion inhibition effect and synergistic mechanism of novel imidazoline derivative (SMIF) and benzimidazole (BMZ) in 3.5 wt% simulated concrete solution were studied experimentally and theoretically. The complex inhibitors have the most outstanding inhibition efficiency when SMIF concentration is 0.1 g/L and BMZ is 0.9 g/L, the corrosion inhibition efficiencies of weight loss, Electrochemical Impedance Spectroscopy and Potentiodynamic polarization curve (Tafel) were 88.81%, 86.27% and 90.22%, respectively. Electrochemistry analysis results proved that the corrosion inhibition mechanism of the inhibitors in the corrosion solution was mainly the formation of a protective film on the surface of carbon steel. FT-IR, Energy Dispersive Spectroscopy and X-ray Photoelectron Spectroscopy all proved the existence of the protective film. Molecular dynamics proved that the composite inhibitor molecules could be stable on the surface of carbon steel and when consist of complex inhibitor was 0.1 g/L SMIF and 0.9 g/L BMZ the stable adsorption morphology were the highest. This work confirmed that SMIF and BMZ inhibitors have a good synergistic effect, greatly improving the inhibition efficiency and reducing the cost of corrosion inhibition, and has a certain guiding significance for synergistic inhibition. [ABSTRACT FROM AUTHOR]

Two N-containing borates, BTES and BMES, were synthesized with dodecyl phenol, 2-(N-containing heterocyclic) ethan-1-ol, boric acid, and dibutylamine, and their tribological properties in rapeseed oil (RSO) were investigated using a four-ball tester. The results showed that the load-carrying ability (PB value) of RSO can be improved by 40.9% and 67.9%, respectively, when using 0.5 wt% BTES and BMES. Moreover, the antiwear and friction-reducing performances of the additive-containing oils increased with the additive concentration. The X-ray photoelectron spectroscopy results of the worn steel ball surfaces showed that BTES and BMES formed protective films, which contained boron oxide, iron oxide, ferrous sulfate, ferrous sulfide (for BMES), and other organic nitrogen compounds, on the metal surfaces. The better load-carrying and antiwear performances of BMES than those of BTES might be due to their different sulfur contents, which result in different tribochemical reaction films on the contact surfaces. The oxidation stability tests showed that BTES and BMES possessed synergistic antioxidation activity with N-phenyl-α-naphthylamine (T531), and consequently, the oxidation activation energy of the oil sample increased by 77.85% and 82.19%, respectively, compared with that of RSO when the oil sample contained 0.05 wt% BTES/BMES and 0.25% T531. [ABSTRACT FROM AUTHOR]

Series of triazine derivatives, 2,4-bi-alkoxy-6-(O,O-dialkyldithiophosphate)-s-1,3,5-triazine, were synthesized. Their tribological properties as lubricating oil additives in vegetable oil were evaluated using a four-ball tester. The results show that these triazine derivatives possess extreme pressure capacity, and they can improve antiwear and friction-reducing performance of base stock. The elements chemical states of the worn surface were estimated through X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM). The results show that a protective film containing sulphide, phosphate and some organic nitrogen compounds was formed on the worn surface during the lubrication process, and the film possesses extreme pressure and antiwear properties. [ABSTRACT FROM AUTHOR]