Objective： To discuss possible relationships between class In malocclusion and perioral forces by measuring the pressure from the lips and the tongue of children with class nI malocclusion. Methods： Thirty-one child...Objective： To discuss possible relationships between class In malocclusion and perioral forces by measuring the pressure from the lips and the tongue of children with class nI malocclusion. Methods： Thirty-one children with class In malocclusion were investigated and their perioral forces were measured at rest and during swallowing under natural head position by a custom-made miniperioral force computer measuring system. Results： The resting pressures exerted on the labial side and palatine side of the upper lett incisor, as well as the labial side and lingual side of the lower lett incisor, were 0 g/cm^2, 0 g/cm^2, 0.57 g/cm^2 and 0.23 g/cm^2, respectively. Correspondingly, the swallowing forces were 2.87 g/cm^2, 5.97 g/cm^2, 4.09 g/cm^2 and 7.89 g/cm^2, respectively. No statistical difference between muscular pressure and gender existed. During swallowing, the lingual forces were significantly higher than the labial forces （P〈0.01）, however, at rest there was no significantly different force between these two sides. Compared to the normal occlusion patients, children with class Ⅲ malocclusion had lower pedoral forces. The upper labial resting forces （P〈0.01）, the lower labial resting forces （P〈0.05） and all the swallowing pressures from the lips and the tongue （P〈0.01） showed statistical differences between the two different occlusion conditions. Meanwhile, no significant difference was found for the resting pressure from the tongue between class Ⅲ malocclusion and normal occlusion. Conclusion： Patients with class Ⅲ malocclusion have lower perioral forces and this muscle hypofunction may be secondary to the spatial relations of the jaws. The findings support the spatial matrix hypothesis.展开更多
The structural and thermodynamic properties of Zr2A1C at high pressure and high temper- ature are investigated by first principles density functional theory method. The calculated lattice parameters of Zr2A1C are in g...The structural and thermodynamic properties of Zr2A1C at high pressure and high temper- ature are investigated by first principles density functional theory method. The calculated lattice parameters of Zr2A1C are in good agreement with the available theoretical data. The pressure dependences of the elastic constants, bulk modulus, shear modulus, Young＇s mod- ulus, and Vickers hardness of Zr2A1C are successfully obtained. The elastic anisotropy is examined through the computation of the direction dependence of Young＇s modulus. By using the quasiharmonic Debye model, the thermodynamic properties including the Debye temperature, heat capacity, volume thermal expansion coefficient, and Griineisen parameter at high pressure and temperature are predicted for the first time.展开更多
基金Project (No.2002ZX040) supported by the Health Bureau of Zhejiang Province,China
文摘Objective： To discuss possible relationships between class In malocclusion and perioral forces by measuring the pressure from the lips and the tongue of children with class nI malocclusion. Methods： Thirty-one children with class In malocclusion were investigated and their perioral forces were measured at rest and during swallowing under natural head position by a custom-made miniperioral force computer measuring system. Results： The resting pressures exerted on the labial side and palatine side of the upper lett incisor, as well as the labial side and lingual side of the lower lett incisor, were 0 g/cm^2, 0 g/cm^2, 0.57 g/cm^2 and 0.23 g/cm^2, respectively. Correspondingly, the swallowing forces were 2.87 g/cm^2, 5.97 g/cm^2, 4.09 g/cm^2 and 7.89 g/cm^2, respectively. No statistical difference between muscular pressure and gender existed. During swallowing, the lingual forces were significantly higher than the labial forces （P〈0.01）, however, at rest there was no significantly different force between these two sides. Compared to the normal occlusion patients, children with class Ⅲ malocclusion had lower pedoral forces. The upper labial resting forces （P〈0.01）, the lower labial resting forces （P〈0.05） and all the swallowing pressures from the lips and the tongue （P〈0.01） showed statistical differences between the two different occlusion conditions. Meanwhile, no significant difference was found for the resting pressure from the tongue between class Ⅲ malocclusion and normal occlusion. Conclusion： Patients with class Ⅲ malocclusion have lower perioral forces and this muscle hypofunction may be secondary to the spatial relations of the jaws. The findings support the spatial matrix hypothesis.
基金This work was supportted by the National Natural Science Foundation of China （No.11447176 and No.11447152）, the National Natural Science Foundation of China and the China Academy of Engineering Physics （No.U1230201）, and the Doctor Foundation of Southwest University of Science and Technology （No.13zx7137 and No.14zx7167）.
文摘The structural and thermodynamic properties of Zr2A1C at high pressure and high temper- ature are investigated by first principles density functional theory method. The calculated lattice parameters of Zr2A1C are in good agreement with the available theoretical data. The pressure dependences of the elastic constants, bulk modulus, shear modulus, Young＇s mod- ulus, and Vickers hardness of Zr2A1C are successfully obtained. The elastic anisotropy is examined through the computation of the direction dependence of Young＇s modulus. By using the quasiharmonic Debye model, the thermodynamic properties including the Debye temperature, heat capacity, volume thermal expansion coefficient, and Griineisen parameter at high pressure and temperature are predicted for the first time.
