Instrumentation for Assessing mTBI Events
Mark A. Mentzer in Mild Traumatic Brain Injury, 2020
Engineering of helmets for improved head protection is an ever-challenging task requiring the characterization of materials to help develop better protection from a variety of impact events. Current characterization methods are limited in arriving at the precise information regarding helmet protection, thereby hindering effective characterization. A high-sensitivity terahertz dynamic reflectometer (TDR) may be used to measure the surface deformation characteristics in real-time (in-situ) and also at post deformation (ex-situ). Real-time measurements can capture layered material deformation kinetics due to impact. Since terahertz radiation can penetrate many composite materials, it produces a clearer picture of the internal material layers of composite laminates and their delamination. A number of crucial parameters can be extracted from the kinetics measurement, such as deformation depth, deformation propagation velocity, and final relaxation position, including vibrational motions of helmets due to impact. In addition, for nonmetallic substrates, a transmitted beam may be used to calibrate mass loss of the laminate layers due to impact. This provides computation of force and energy of impact in real-time.
Mitral Valve Mechanics
Michel R. Labrosse in Cardiovascular Mechanics, 2018
During embryonic development, the atrioventricular canals form by the fusion of the superior and inferior endocardial cushions. The interatrial and interventricular septa separate the left and right hearts. The mitral valve develops in the left atrioventricular canal. Initially, the microscopic dissection of embryonic hearts found that very little of the septal leaflet consisted of endocardial cushion tissue. This led to the hypothesis that the cushions played a lesser role in the development of the valve [1,2]. Further investigation revealed that the septal (anterior) leaflet derives from the superior and inferior endocardial cushions. At the site of endocardial cushions, endothelial cells migrate and invade the cardiac jelly and differentiate into mesenchymal cells [3]. These cells continue to proliferate, allowing the formation of thin fibrous valve tissue. The mural (posterior) leaflet of the mitral valve develops from a mesenchymal cushion that is laterally located. The leaflets are further defined by undermining of the myocardium, leaving behind trabeculated structures corresponding to chordae tendinae. The leaflets comprise connective tissue, namely collagen, elastin, and glycosaminoglycans, collectively known as an extracellular matrix. Delamination of the valve gives way to the anterior and posterior leaflets. The delamination process ends at the commissures. Still, the precise mechanism of heart valve development remains poorly understood. Overall, it is a complex and intricate process, potentially governed by a network of signaling pathways [4,5].
Nail Product Rheology
Laba Dennis in Rheological Proper ties of Cosmetics and Toiletries, 2017
The platelet stacks are wetted out as the application of shear enables solvent and vehicle to penetrate the capillary interstices, resulting in deagglomerated platelet stacks. Note that the order of addition of components can be critical. Surfactants and poor wetting oils and resins can encapsulate the stacks, resulting in prevention of both dispersion and delamination. Such materials should be added only after the organoclay has been polar activated (26). The viscosity of the system increases, but only a small portion of the ultimate gel strength is attained at this point. The solvation force keeps the platelets in suspension. Addition of a polar additive under shear conditions forces the platelets apart. Continued shear drives the platelets farther apart to form an active rheological structure. Some organoclays have been designed which are treated so that when they are dispersed in the proper solvent, they do not require a polar additive (26).
Device profile of the Orchid safety release valve for the prevention of accidental catheter dislodgement
Published in Expert Review of Medical Devices, 2023
Nancy Moureau
Stress testing was performed for simulation of clinical conditions, which included connection to IV fluid administration tubing, use of commercially available securement devices, and application in porcine skin. Performance was tested for force activation and separation sealing. Catheter dislodgement was defined as the complete removal of the catheter from the skin. Delamination was defined as loss of dressing adherence with complete or partial peeling off the skin. For purposes of the study, catheter failure requiring a new dressing was defined as the replacement of the IV catheter, securement device, tape, and transparent dressing, when applicable, to the test case. Samples of the SRV consisted of ethylene oxide (EtO) sterilized, non-aged (T = 0), and real-time samples aged 1.8 years. By spacing the age range at both ends of the aged spectrum, the largest reflection of real-world potential usage was achieved. The study also examined the effect of securement on the IV catheter and administration tubing with both transparent dressing, and transparent dressing with securement.
Analytical review on the biocompatibility of surface-treated Ti-alloys for joint replacement applications
Published in Expert Review of Medical Devices, 2022
Shubham Jain, Vishal Parashar
Delamination generally annihilates a coating’s solidarity and sturdiness. This makes the substrate less resistant to corrosion. When corrosive media have direct admittance to a metal substrate, electrochemical reactions will happen at the metal-coating interface within sight of water, making delamination. A decent defensive covering requires tight holding between the coating and metal substrate to oppose water infiltration to the interface. The mechanical bond is genuinely significant to guarantee an excellent coating adhesion. The contact region extends by enhancing the surface roughness of metals, further developing the grip between the covering and substrate metal. Hence delamination can reduce.
Exploring the functionalization of Ti-6Al-4V alloy with the novel antimicrobial peptide JIChis-2 via plasma polymerization
Published in Biofouling, 2023
Gabriella Teresinha Lima Teixeira, Rogério Valentim Gelamo, Malu Mateus Santos Obata, Leonardo Eurípedes de Andrade Silva, Marcos Vinícius da Silva, Carlo José Freire de Oliveira, Brunela Pereira da Silva, Idalina Vieira Aoki, Jeferson Aparecido Moreto, Natália Bueno Leite Slade
Regarding the surfaces on which the peptide is immobilized, the OM images for immersion tests are shown in Figure S4. Through this, it is possible to notice that there is a corrosion process very similar to the Ti-6Al-4V/PAA samples. Therefore, regions of delamination in the film are observed along this surface after 3 h of immersion, Figure S4d. As previously emphasized, delamination in these samples occurs due to the presence of irregularities on the metal surface after PAA deposition. However, the presence of pitting is observed only in the bare material in the first hours of immersion, showing once again that the PAA coating acts as a protective barrier for the Ti-6Al-4V alloy.
Related Knowledge Centers
- 3D Printing
- Carbon Fibers
- Epoxy
- Lamination
- Ultrasound
- Composite Material
- Concrete
- Fibre-Reinforced Plastic
- Fiberglass
- Visual Inspection