Origami tubes with reconfigurable polygonal cross-sections.

Thin sheets can be assembled into origami tubes to create a variety of deployable, reconfigurable and mechanistically unique three-dimensional structures. We introduce and explore origami tubes with polygonal, translational symmetric cross-sections that can reconfigure into numerous geometries. The tubular structures satisfy the mathematical definitions for flat and rigid foldability, meaning that they can fully unfold from a flattened state with deformations occurring only at the fold lines. The tubes do not need to be straight and can be constructed to follow a non-linear curved line when deployed. The cross-section and kinematics of the tubular structures can be reprogrammed by changing the direction of folding at some folds. We discuss the variety of tubular structures that can be conceived and we show limitations that govern the geometric design. We quantify the global stiffness of the origami tubes through eigenvalue and structural analyses and highlight the mechanical characteristics of these systems. The two-scale nature of this work indicates that, from a local viewpoint, the cross-sections of the polygonal tubes are reconfigurable while, from a global viewpoint, deployable tubes of desired shapes are achieved. This class of tubes has potential applications ranging from pipes and micro-robotics to deployable architecture in buildings.

Regarding extremely large inguinal hernias with a contribution of two cases.

We report two men of ages 62 and 80 years, respectively, with giant inguinoscrotal hernias. They were operated with a single-stage repair by two approaches, extended preperitoneal of Nyhus and an inguinal method. After hernia content reduction, a policaproamide antimicrobial mesh Ampoxen (MEDICA SA, Sandanski, Bulgaria) with dimensions 20 x 30 cm was inserted by using Stoppa's technique. An additional inguinal reinforcement with other mesh patch was done on the external aponeurosis hernial defect. Synchronous orchiectomy and transscrotal drainage of both patients was performed. The first patient suffering from umbilical hernia was also operated at the same stage. He was prepared by preoperative pneumoperitoneum. The second patient, due to scrotal skin cellulitis with ulceration, was operated without pneumoperitoneum preparation. The latter created easier mobilization and reduction of the hernial content. The sizable mesh dimensions allowed, to some degree, an acceptable level of intra-abdominal pressure after the repair. These hernias demand interdisciplinary teamwork and their treatment has to be adapted to the individual condition of the patient using all therapeutic options.