A nomogram for assisting in diagnosing mouth breathing based on maxillofacial surface electromyographic activity

Abstract Objective A nomogram based on maxillofacial surface electromyographic (sEMG) activities was developed to assist in diagnosing mouth breathing (MB). Methods Differences in maxillofacial sEMG activities between MB and nasal breathing (NB) subjects were compared across a sample of 250 participants to identify MB diagnostic factors, a nomogram was developed to assist in diagnosing MB. Results In the univariate analysis, there were significant differences in sEMG activity of masseter muscle with the lips closed lightly, orbicularis oris superior during rest, orbicularis oris superior with the lips closed lightly (OOS3), orbicularis oris superior during swallowing, mentalis muscle during rest, mentalis muscle during maximal intercuspation (MT2), mentalis muscle with the lips closed lightly (MT3) and mentalis muscle during swallowing between the MB and NB groups. Multivariate analysis revealed that OOS3 and MT3 were independent risk factors for MB, while MT2 might be a protective factor against MB. The nomogram exhibited a good clinical application value with an area under the ROC curve of 0.774 (95% CI 0.713–0.834) and fitted calibration curves. Conclusion MB could affect maxillofacial sEMG activities. We developed a nomogram to assist in diagnosing MB in the clinic. Clinical significance The nomogram can help clinicians diagnose MB quickly and easily, providing a more effective way to diagnose children with MB early so that they can receive timely treatment and block abnormal neuromuscular reflexes early, thereby avoiding the harmful effects of MB

Microstructure evolution and improved surface properties of Ti-6Al-3Nb-2Zr-1Mo alloy by laser shot peening

Abstract In this work, the surface modification of Ti-6Al-3Nb-2Zr-1Mo (Ti80) alloy was performed by laser shock peening (LSP). The resultant microstructure, mechanical properties and corrosion properties of LSP-treated (LSPed) Ti80 were systematically investigated by 3D profiler, x-ray diffractometer (XRD), optical microscope (OM), transmission electron microscope (TEM), scanning electron microscope (SEM), microhardness tester, tensile tester and electrochemical workstation. LSP induced significant number of dislocations through plastic deformation, forming many defects such as dislocation tangles, stacking faults and deformation twins. The surface grain was severely refined due to severe plastic deformation at the surface. Microhardness improved substantially by 26.7%, compressive residual stress reached its maximum value (−307 MPa), and both microhardness and compressive residual stress presented a gradient change along depth. The tensile properties were improved by the action of work hardening, grain refinement and compressive residual stresses after LSP. The fracture changed from typical ductile to mixed ductile and brittle fracture. Grain refinement provides more nucleation sites for the formation of passivation film, while impurities are not easily segregated at grain boundaries, retarding intergranular corrosion, high-density dislocations hinder electron transfer and reduce corrosion current density, resulting in a significant improvement in the corrosion resistance of Ti80 alloy in 3.5% NaCl and 5M HCL solution