On the Reuse of SLS Polyamide 12 Powder.

In the Selective Laser Sintering (SLS) technique, the great majority of the powder involved is not included in the final printed parts, being just used as a support material. However, the quality of this powder is negatively affected during the process since it is subjected to high temperatures (close to its melting temperature) during a long time, i.e., the printing cycle time, especially in the neighborhood of the printed part contour. This type of powder is relatively expensive and large amounts of used powder result after each printing cycle. The present paper focuses on the reuse of Polyamide 12 (PA 12) powder. For this sake, the same PA 12 powder was used in consecutive printing cycles. After each cycle, the remaining non-used powder was milled and filtered before subsequent use. Properties of the powder and corresponding prints were characterized in each cycle, using differential scanning calorimetry (DSC), scanning electron microscopy (SEM), computed tomography (CT), and tensile tests. It was concluded that subjecting the same powder to multiple SLS printing cycles affects the properties of the printed parts essentially regarding their morphology (voids content), mechanical properties reproducibility, and aesthetical aspect. However, post-processing treatment of the powder enabled to maintain the mechanical performance of the prints during the first six printing cycles without the need to add virgin powder.

Right adrenal gland prospective evaluation through transgastric endoscopic ultrasound: an alternative approach.

Background and aims: Endoscopic ultrasound (EUS) guided right adrenal gland (RAG) evaluation is frequently unsuccessful and, when feasible, requires a cumbersome maneuver through the duodenum. In our experience, the use of a recent ultrasound platform has enabled transgastric detection of the RAG with a simple maneuver. The aim of this study was to determine the RAG transgastric EUS detection rate and identify predictive factors for failure. Methods: Consecutive patients referred to EUS in a single center were prospectively included over a 6-month period. Success was defined as RAG transgastric EUS detection within 180 seconds. Logistic regression analysis was used to assess factors associated with failure. Results: Among 100 patients, the success rate for RAG transgastric EUS detection was 75 %, with a median maneuver duration of 45 seconds [interquartile range, 25 - 70 seconds]. Two incidental RAG lesions were detected. Of possible demographic and anthropometric predictive factors for failure, only age (OR 1.04; P = 0.04) was statistically significant on multivariate analysis. Conclusions: The transgastric EUS approach for RAG detection is simple, fast and effective.