The treatment of early onset scoliosis using surgical growing rods suffers from high failure rate. Fatigue resistance can be improved by inducing compressive residual stresses within the near surface region. An in-depth investigation of the residual stresses profile evolution is performed through the sequence of material processing steps followed by surgeons handling operations, in connection to material properties. The final goal is to guide further improvements of growing rod lifetime. Residual stress evaluation was carried out on Ti-6Al-4V rods using digital image correlation applied to microbeam ring-core milling by focused ion beam. This provided experimental stress profiles in shot-peened rods before and after bending and demonstrated that compressive residual stresses are maintained at both concave and convex rod sides. A finite element model using different core and skin conditions was validated by comparison to experiments. The combination of an initial shot peening profile associated with a significant level of backstress was found to primarily control the generation of compressive stresses at the rod surface after bending. Guidelines to promote larger compressive stresses at the surface were formulated based on a parametric analysis. The analysis revealed the first order impact of the initial yield strength, kinematic hardening parameters and intensity of the shot peening operation, while the bending angle and the depth of shot peening stresses were found to be of minor importance. Materials exhibiting large kinematic hardening and low yield strength should be selected in order to induce compressive residual stresses at key fatigue initiation site.
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http://dx.doi.org/10.1115/1.4063745 | DOI Listing |
Adv Healthc Mater
January 2025
Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, College of Bioengineering, Chongqing, 400044, P. R. China.
Decellularized artificial blood vessels prepared using physical and chemical methods often exhibit limitations, including poor mechanical performance, susceptibility to inflammation and calcification, and reduced patency. Cross-linking techniques can enhance the stiffness, as well as anti-inflammatory and anti-calcification properties of decellularized vessels. However, conventional cross-linking methods fail to effectively alleviate residual stress post-decellularization, which significantly impacts the patency and vascular remodeling following the implantation of artificial vessels.
View Article and Find Full Text PDFCan J Cardiol
January 2025
Research Center, Montreal Heart Institute, Department of Medicine, Université de Montréal, Montreal, Canada; Adult Congenital Heart Centre, Montreal Heart Institute, Université de Montréal, Montreal, Canada. Electronic address:
In congenital heart diseases (CHD) of moderate to great complexity involving the right ventricle (RV), the morphologic RV can be exposed to significant stressors across the lifespan either in a biventricular circulation in a sub-pulmonary or sub-aortic position, or as part of a univentricular circulation. These include pressure and/or volume overload, hypoxia, ischemia, and periprocedural surgical stress leading to remodeling, maladaptation, dilation hypertrophy and dysfunction. This review examines the macroscopic remodeling of the RV in various forms of CHD and explores remodeling trajectories, along with the effects of surgeries and residual lesion repair, in tetralogy of Fallot, Ebstein anomaly, congenitally corrected transposition of the great arteries, transposition of the great arteries with atrial switch surgery, and single ventricle palliated by Fontan.
View Article and Find Full Text PDFInt J Pharm
January 2025
Holistic Integrative Medicine Industry Collaborative Innovation Research Center, Qiang Medicine Standard Research Promotion Base and Collaborative Innovation Research Center, School of Preclinical Medicine, Chengdu University, Sichuan-Chengdu 610106, China. Electronic address:
Gastric ulcers often cause postprandial epigastric pain, especially in acute cases. Abnormal motility, with about 50 % of patients having delayed gastric emptying, contributes to ulcer development. Costunolide (COS) and dehydrocostuslactone (DEH), derived from "Mu xiang" herbs, show potential in treating ulcers and regulating gastrointestinal motility.
View Article and Find Full Text PDFJ Psychiatr Res
January 2025
Psychological Health and Readiness, Naval Health Research Center, San Diego, CA, USA. Electronic address:
Despite effective psychotherapy options for posttraumatic stress disorder (PTSD), some patients do not fully respond, and even among those reporting substantial improvement, residual symptoms following treatment are common. Psychiatric conditions frequently co-occur with PTSD, yet research on residual symptoms among comorbid samples is lacking. This study examined residual symptoms of PTSD and depression among 71 active duty service members with PTSD and comorbid major depressive disorder (MDD).
View Article and Find Full Text PDFMaterials (Basel)
January 2025
School of Materials Science and Engineering, Southeast University, Nanjing 211189, China.
Optimized heat treatment processes for high-strength, low-alloy steel are studied in order to maximize the strengthening effects of the alloying elements and achieve a favorable balance of strength and ductility. In this study, it is found that high-energy-density electric pulse treatment (EPT) can effectively reduce the residual stress in quenched high-strength, low-alloy steel. Furthermore, EPT promotes the precipitation of fine needle-like ε-carbides and small spherical MC carbides.
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