A piezoelectric single-pole single-throw (SPST) switch has been developed, since there is no satisfying commercial low-resistance, high current DC-contact RF switch available which is operable at ...4.2K and in a high magnetic field of at least 0.5T. This piezoelectric switch shows very low insertion loss of less than −0.1dB within a bandwidth of 100MHz when operated at 4.2K. The switch could also be used to mechanically disconnect and connect electrodes or electrical circuits from one another.
In a rat model, nerve regeneration was evaluated across a 2-cm defect in the median nerve by using a resorbable artificial nerve conduit. The aim of this study was to develop an artificial, ...biocompatible nerve guide to induce regeneration in the peripheral nervous system.
The authors compared a nerve conduit of trimethylenecarbonate-co-epsilon-caprolactone (TMC/CL) filled with autologous Schwann cells with both an empty hollow conduit and an autologous nerve graft. Animals that did not undergo surgery served as the control group. Nerve regeneration was evaluated with the grasping test, histological analysis of the nerve, muscle weight analysis (flexor digitorum superficialis muscle), and electrophysiological examination. After an observation period of 9 months, regeneration occurred only in animals that had received an autologous graft or a Schwann cell containing nerve conduit. No signs of regeneration were found in animals supplied with the empty conduit.
Results of this study reveal the important role of Schwann cells in the regeneration process across a 2-cm defect in the rat median nerve. Furthermore, Schwann cell-filled nerve conduits induced functional recovery, as demonstrated in the grasping test, that was comparable with that of the autologous graft 9 months after implantation.
The purpose of this study was to evaluate the effect of different adaptation phases on the shear-stress resistance of endothelial cells seeded artificially onto vascular prostheses and biological ...heart valves.
Human endothelial cells (EC), fibroblasts (FB), and smooth muscle cells (SMC) were isolated from vena saphena magna pieces and expanded in culture. Group A: 15 polyurethane vascular grafts (20 mm diameter) were seeded with FB and SMC (53 +/- 1.2 million cells), followed by EC seeding (39 +/- 0.9 million cells). Group B: eight stentless porcine valves (Freestyle, Medtronic, USA) were seeded with FB (68 +/- 1.5 million cells) and EC (42 +/- 1.1 million cells). Shear-stress testing was done under pulsatile flow (pulse rate: 80 pulses/min.). Adaptation phase: flow was set to 0.9 +/- 0.3 l/min (systolic pressure: 40 - 50 mm Hg). High flow was 3.2 +/- 0.6 l/min. (systolic pressure: 140 - 160 mm Hg) and lasted over four hours in all groups. The vascular grafts were divided into three groups (n = 5 each): group 1 (high flow immediately), group 2 (adaptation phase of 15 minutes), and group 3 (adaptation phase of 30 minutes). The valves either were given high flow immediately (n = 4) or had an adaptation phase of 30 minutes (n = 4). Specimens were obtained after cell seeding, before, and after perfusion.
A confluent EC layer was achieved on all grafts. After perfusion without adaptation, large defects within the cell layer were found. No FB and SMC were seen at the bottom of these defects. In group B, the defects were largest on the ventricular surface of the leaflets. After an adaptation phase of 15 minutes in group A, only a few defects within the EC layer were detected with a still confluent FB and SMC. After a 30-minute adaptation phase defects within the EC layer were very rare and no interruption of the underlying FB and SMC layer was seen. Immunohistochemical staining for factor VIII and CD31 proved the EC to be viable and staining for collagen IV and laminin revealed the formation of a basement membrane. After perfusion, the specimen also stained positive for eNOS.
An adaptation phase of 30 minutes proved to be sufficient to allow artificially seeded endothelial cells to adapt to shear stress. The formation of a basement membrane was of great importance for the maintenance of a confluent EC layer.
A powerful and robust control system is a crucial, often neglected, pillar of any modern, complex physics experiment that requires the management of a multitude of different devices and their precise ...time synchronisation. The AEḡIS collaboration presents CIRCUS, a novel, autonomous control system optimised for time-critical experiments such as those at CERN’s Antiproton Decelerator and, more broadly, in atomic and quantum physics research. Its setup is based on Sinara/ARTIQ and TALOS, integrating the ALPACA analysis pipeline, the last two developed entirely in AEḡIS. It is suitable for strict synchronicity requirements and repeatable, automated operation of experiments, culminating in autonomous parameter optimisation via feedback from real-time data analysis. CIRCUS has been successfully deployed and tested in AEḡIS; being experiment-agnostic and released open-source, other experiments can leverage its capabilities.
Many patients suffering from end-stage liver disease cannot be transplanted within reasonable time due to the shortage of donor organs. Bioartificial liver support systems may contribute to the liver ...regeneration or bridging the time until a liver graft for transplantation becomes available. Nonwovens with integrated oxygenation capacity have been developed and manufactured by melt blow technology using thermoplastic polyurethane. Capillary membranes for oxygenation were integrated into the nonwoven during the processing. The polyurethane nonwoven structures with adapted pore size and high pore volume allow high cell densities in the hepatocyte culture. The three-dimensional cell culture was housed by a flow bioreactor system and was integrated in a closed loop circulation with monitoring possibilities for pressure, pH, temperature, ammonia, and oxygen. Hepatocytes were isolated from rats or pigs by collagenase perfusion and infused into the medium-perfused circulation. Cells showed high viability and hepatocyte specific cytochrome P450-dependent metabolic function in culture (MEGX test).
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