The tip and die for manufacturing multi-lumen catheter tubes should be designed considering the flow velocity of the molten polymer and the deformation of the final extruded tube. In this study, to manufacture non-circular double-lumen tubes for peripherally inserted central catheters (PICCs), three types of tip and die structures are proposed. The velocity field and swelling effect when the circular tip and die (CTD) are applied, which is the commonly used tip and die structure, are analyzed through numerical calculation. To resolve the wall and rib thickness and ovality issues, the ellipse tip and die (ETD) and sub-path tip and die (STD) were proposed. In addition, based on the results of numerical analysis, the tip and die structures were manufactured and used to perform extrusion. Finally, we manufactured tubes that satisfied the target diameter, ovality, wall, and rib thickness using the newly proposed STD.
A series of poly(ADP-ribose) polymerase-1 (PARP-1) inhibitors, 5-oxo-2,4,5,6-tetrahydro-1H-thiopyrano[3,4-c]quinoline-9-carboxamide derivatives, were successfully synthesized and their PARP-1 inhibitory activity was evaluated. These compounds were prepared from carboxylic acid 7 and the appropriate amines, and a number of the synthesized compounds were found to have significant PARP-1 activity. Among them, 9m showed potent activity in a PARP-1 enzymatic assay and cell-based assay (IC 50 = 0.045 lM, ED 50 = 0.54 lM). Molecular modeling studies confirmed the obtained biological results.
As interventional procedures using catheters have rapidly developed, accordingly, the incidence of polymeric embolization is also increasing, with the main cause being the flash generated during tip forming of the catheter. This study has performed to change the material of the mold used to form catheter tips to prevent flash, which is a cause of polymeric embolism. The tip‐forming performance and the flash generation according to the main parameters of the tip‐forming process were analyzed: power, heating, cooling time, and insertion pressure. In addition, we observed the effect of flash suppression according to temperature sensitivity by changing the mold material considering thermal conductivity and electrical resistivity. In particular, considering the glass transition temperature of HDPE (high‐density polyethylene), which is applied to sheath and dilator catheters, the most stable tip forming proceeds when the temperature near the tip inside the mold was about 130°C. We verified experimentally and numerically that the temperature of the pins comprising the mold plays an important role in flash generation and confirmed that the viscosity of the polymer melts is lower at 120°C than at 90°C of the pin, and flash is minimized because of the shear‐thinning behavior of the polymer melts.
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