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Background: Numerous studies have proposed that periodontitis is a potential risk factor for Alzheimer's disease. However, the association between periodontitis and brain normal cognition in aged and elderly individuals (NCs) is unclear. Such a link could provide clues to Alzheimer's disease development and strategies for early prevention. Objective: To explore the associations between periodontal condition and metrics of both brain structure and function among NCs with the help of multimodal magnetic resonance imaging (MRI). Methods: High‐resolution T1‐weighted structural data, resting‐state functional‐MRI data, and measures of periodontal condition were collected from 40 NCs. Cortical volume, thickness, and area as well as regional homogeneity were calculated with the aid of DPABISurf software. Correlation analyses were then conducted between each imaging metric and periodontal index. Results: Consistent negative correlations were observed between severity of periodontitis (mild, moderate, severe) and cortical volume, area, and thickness, not only in brain regions that took charge of primary function but also in brain regions associated with advanced cognition behavior. Among participants with mild attachment loss (AL) and a shallow periodontal pocket depth (PPD), periodontal index was positively correlated with most measures of brain structure and function, while among participants with severe AL and deep PPD, periodontal index was negatively correlated with measures of brain structure and function (all p <.005 for each hemisphere). Conclusions: Our results demonstrate that periodontitis is associated with widespread changes in brain structure and function among middle‐aged and elderly adults without signs of cognitive decline, which might be a potential risk factor for brain damage. [ABSTRACT FROM AUTHOR]

The MCrAlY bonding layer alloy was prepared by vacuum melting, and the alloy composition was NiCoCrAlY and NiCoCrAlYHfTa. The high-temperature cyclic oxidation experiment was carried out in air at 1050∘C until it failed. The results show that Hf and Ta have a significant influence on the oxidation resistance of the alloy. The doped specimens have longer oxidation lifetimes compared to the undoped samples. The study also found that the Hf would diffuse out and combine with O to form HfO2 in the thermally grown oxide (TGO) layer, which would improve the adhesion and reduce the wrinkles of the oxide layer. Ta in the doped specimens hinders the diffusion of Al and reduces the oxidation rate, while improving the thermal mismatch. Therefore, the specimens doped with both Hf and Ta have the highest oxidation lifetimes, though the oxidation lifetime was 10 times longer than that of the undoped specimens. It is indicated that the doping of Hf and Ta is an important method to improve the oxidation lifetime of thermal barrier coatings (TBCs). [ABSTRACT FROM AUTHOR]

In order to effectively simulate the time-dependent, nonlinear and multiphysics response of the new type of multi-functional smart materials-metal core piezoelectric and piezomagnetic fiber reinforced polymer matrix composite (MPPF/PMC), an incremental micromechanics model was developed based on the variational asymptotic method. Firstly, the incremental constitutive equations of polymer, piezoelectric/piezomagnetic materials and metal materials were derived respectively, and a unified constitutive equation was established. Considering the time-dependent and nonlinear characteristics of composites, an incremental procedure in conjunction with an instantaneous tangential electro-magneto-mechanical matrix of composites was established. The fluctuate functions of field variables were solved by minimizing the approximate energy functional and realized by finite element method, resulting in a micromechanics model as close as possible to the physical and engineering authenticity. The numerical example of aluminum core piezoelectric (BaTiO3) and piezomagnetic (CoFe2O4) polymer matrix shows that this constructed model can be used to simulate the effective response of MPPF/PMCs under different physical fields and can accurately capture the stress mutation phenomenon between the fiber and the matrix. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed to determine the association of periodontitis with cognitive impairment by evaluating periodontal conditions in middle-aged and elderly people of normal cognition and cognitive impairment., Methods: Forty patients with cognitive impairment and thirty-five healthy controls were included in this study. Mini-mental state examination (MMSE) was used to evaluate the level of cognitive function in all patients and controls. Periodontal conditions including severity of periodontitis, number of remaining teeth, percentage of bleeding on probing, probing depth (PD), and attachment level (AL) were examined. Periodontal conditions were compared between patients and controls, and the correlation between periodontal conditions and cognitive-function level was analyzed. Statistical analysis was performed with SPSS 26.0., Results: The distribution of severity of periodontitis significantly differed between patients and controls ( χ 2 =13.309 and P =0.001). The proportion of severe periodontitis in the cognitive-impairment group was significantly higher than that in the healthy controls ( P <0.05). The percentage of sites with PD≥6 mm and AL≥5 mm in the cognitive-impairment group was higher than that in the controls, whereas the percentage of sites with PD=1-3 mm and AL=0-2 mm was higher in the controls ( P <0.05). No significant difference in percentage of bleeding on probing was found in the two groups ( P >0.05). Patients with cognitive impairment had fewer teeth than the controls ( P <0.05). The level of cognitive function, assessed by MMSE, was positively correlated with the number of teeth and the percentage of sites with AL=0-2 mm, and it was negatively correlated with the percentage of sites with AL≥5 mm ( P <0.05)., Conclusions: A correlation existed between periodontitis and cognitive impairment. Further study is essential to explore the specific relationship and related mechanism between periodontitis and cognitive impairment.