Introduction: This study aims to evaluate the influence of the biomechanical behavior of the midpalatal suture (MPS) during the rapid maxillary expansion (RME) when modeled by the Finite Element Method. Methods: Four simulation alternatives are discussed and, for each analysis, the suture is considered as a functional unit with a different mechanical behavior: (i) without MPS elements, (ii) MPS with Young's modulus (E) equal to 1 MPa, (ii) MPS with E equal to 0.01 MPa and (iv) MPS with bilinear elastic behavior. Results: The stress analysis showed that, when MPS is not considered in the model, stress peaks are reduced in magnitude and their distribution is restricted to a smaller area when compared to the model with the inclusion of MPS (E=1 MPa).The increased suture stiffness also has a direct influence on MPS displacements after 30 expander activations.
Conclusion:The consideration of the MPS in RME computer models influences greatly the calculated displacements between the suture bone ends, even as the stress levels in maxillary structures. Furthermore, as proposed for the described model, the elastic bilinear behavior assigned to MPS allows coherent prediction of stresses and displacements results, being a good representation for this suture overall behavior.
Rotational stresses from box-post impingement have been implicated in the loosening of posterior-stabilized total knee prostheses. A bench model was constructed to assess the forces generated by tibiofemoral rotation. Rotational torque under load was measured in two different posteriorstabilized total knee prostheses using an axial-torsion load cell at 0 degrees, 20 degrees, and 40 degrees flexion over 20 degrees internal and external rotation. The Sigma posterior-stabilized prosthesis generated little torque through 5 degrees internal and external rotation. An increase in torque then occurred because of box-post impingement, generating peak torques of 17 to 18 N-m at 12 degrees to 14 degrees rotation. The bench model produced the same deformation of the polyethylene post as seen on retrieved specimens. The Scorpio posterior-stabilized prosthesis had a relatively continuous rise in generated torque from tibiofemoral conformity. Box-post impingement did not occur resulting in 32% lower torque between 12 degrees and 14 degrees rotation. Peak rotational torques of 15 to 16 N-m were reached at 19 degrees to 20 degrees rotation. Tibiofemoral conformity is the primary source of rotational constraint. Box-post impingement can be a source of additional rotational constraint. Depending on specific design features, small changes in relative tibiofemoral component rotation can more than double the generated torque. Axial rotation of the knee in vivo can generate substantial torque. Relative tibiofemoral rotational position is an important factor influencing component function and fixation.
Недавние достижения в области нанотехнологии, в том числе современные методы, позволяющие усовершенствовать технологии приготовления лекарственных средств, открыли новые горизонты в наномедицине, связанные с разработкой наноразмерных средств доставки лекарственных препаратов и целых комплексов. Последнее десятилетие большое внимание уделяется использованию нанопереносчиков ― усилия исследователей направлены не столько на разработку новых препаратов, сколько на поиск способов целевой доставки терапевтических и/или диагностических агентов. В работе рассмотрены трансдисциплинарный подход к получению наноматериалов, нанокомплексов, нановезикул и перспективы их применения в биологии и тераностике. Особое внимание уделено получению нанопузырьков, стимулчувствительных наночастиц и наносистем с привитым циклодекстрином при нестандартных условиях, таких как действие ультразвука и микроволнового излучения. Помимо использования в процессе приготовления наночастиц, ультразвук может также эффективно применяться для активации чувствительных нановезикул и наночастиц.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.