ABSTRACT
Based on the NASA in-Space Assembled Telescope (iSAT) study (Bulletin of the American Astronomical Society, 2019, 51, 50) which details the design and requirements for a 20-m parabolic in-space telescope, NASA Langley Research Center (LaRC) has been developing structural and robotic solutions to address the needs of building larger in-space assets. One of the structural methods studied involves stackable and collapsible modular solutions to address launch vehicle volume constraints. This solution uses a packing method that stacks struts in a dixie-cup like manner and a chemical composite bonding technique that reduces weight of the structure, adds strength, and offers the ability to de-bond the components for structural modifications. We present in this paper work towards a soft material robot end-effector, capable of suppling the manipulability, pressure, and temperature requirements for the bonding/de-bonding of these conical structural components. This work is done to investigate the feasibility of a hybrid soft robotic end-effector actuated by Twisted and Coiled Artificial Muscles (TCAMs) for in-space assembly tasks. TCAMs are a class of actuator which have garnered significant recent research interest due to their allowance for high force to weight ratio when compared to other popular methods of actuation within the field of soft robotics, and a muscle-tendon actuation design using TCAMs leads to a compact and lightweight system with controllable and tunable behavior. In addition to the muscle-tendon design, this paper also details the early investigation of an induction system for adhesive bonding/de-bonding and the sensors used for benchtop design and testing. Additionally, we discuss the viability of Robotic Operating System 2 (ROS2) and Gazebo modeling environments for soft robotics as they pertain to larger simulation efforts at LaRC. We show real world test results against simulation results for a method which divides the soft, continuous material of the end-effector into discrete links connected by spring-like joints.
ABSTRACT
Q fever is a rare systemic infection caused by Coxiella Burnetii. The presentation with endocarditis is insidious, with negative blood cultures, and oftentimes it is not obvious in diagnostic imaging studies until hemodynamic changes or valve destruction is reached. We report a case of Q fever endocarditis involving the tricuspid and aortic valves and a congenital ventricular septal defect. Surgical treatment and distinct aspects of this unusual case are herein described.
Subject(s)
Aortic Valve Stenosis/etiology , Endocarditis, Bacterial/complications , Heart Septal Defects, Ventricular/etiology , Q Fever/complications , Tricuspid Valve Insufficiency/etiology , Acute Disease , Adult , Antibodies, Bacterial/analysis , Aortic Valve Stenosis/diagnostic imaging , Aortic Valve Stenosis/surgery , Coxiella burnetii/immunology , Diagnosis, Differential , Echocardiography, Transesophageal , Embolization, Therapeutic/methods , Endocarditis, Bacterial/diagnosis , Endocarditis, Bacterial/microbiology , Follow-Up Studies , Heart Septal Defects, Ventricular/diagnosis , Heart Septal Defects, Ventricular/therapy , Heart Valve Prosthesis Implantation/methods , Humans , Male , Q Fever/diagnosis , Q Fever/microbiology , Tricuspid Valve Insufficiency/diagnostic imaging , Tricuspid Valve Insufficiency/surgeryABSTRACT
Postoperative tricuspid valve regurgitation is moderate to severe in 15% to 20% of heart transplant recipients despite use of the bicaval surgical technique. We hypothesized that the regurgitation might be partly due to increased tension on the donor right atrium. To study the right atrial distortion, we modified the standard bicaval anastomosis. Our technique involves augmenting the donor right atrial anterior wall with a flap of the recipient's right atrium, which is left attached in continuity with the anterior aspect of the inferior vena cava along 65% of its circumference. We measured tricuspid regurgitation, right atrial area, and right atrioventricular diameter in 7 consecutive patients who underwent orthotopic heart transplantation with the modified anastomosis. Tricuspid regurgitation was graded as follows: 1 = trace, <10%; 2 = mild, 10%-24%; 3 = moderate, 25%-50%; and 4 = severe, >50%. All patients were weaned from inotropic support within 1 week after transplantation with excellent ventricular function, no heart block, and 100% survival at 30 days. The median follow-up time was 173 days (44-358 days). Other median measurements included tricuspid valve regurgitation jet area, 0.30 cm(2) (0-1.90 cm(2)); right atrial area, 15.90 cm(2) (14.47-18.00 cm(2)); atrioventricular diameter, 2.70 cm (2.63-3.09 cm); and tricuspid regurgitation, 1.67% (0-12.42%). Mild regurgitation occurred in 1 recipient; in all others, it was trace. The modified inferior vena caval anastomosis is simple and safe. It eliminates moderate and severe tricuspid valve regurgitation without routine annuloplasty after orthotopic heart transplantation via the bicaval technique.
