Cenospheres-Reinforced PA-12 Composite: Preparation, Physicochemical Properties, and Soaking Tests.

The main aim of this research was the preparation of a polymer-ceramic composite with PA-12 as the polymer matrix and modified aluminosilicate cenospheres (CSs) as the ceramic filler. The CSs were subjected to an early purification and cleaning process, which was also taken as a second objective. The CSs were surface modified by a two-step process: (1) etching in Piranha solution and (2) silanization in 3-aminopropyltriethoxysilane. The composite was made for 3D printing by FDM. Raw and modified CSs and a composite with PA-12 were subjected to the following tests: surface development including pores (BET), real density (HP), chemical composition and morphology (SEM/EDS, FTIR), grain analysis (PSD), phase composition (XRD), hardness (HV), and static tensile tests. The composites were subjected to soaking under simulated body fluid (SBF) conditions in artificial saliva for 14, 21, and 29 days. Compared to pure PA-12, PA-12_CS had generally better mechanical properties and was more resistant to SBF at elevated temperatures and soaking times. These results showed this material has potential for use in biomedical applications. These results also showed the necessity of developing a kinetic aging model for aging in different liquids to verify the true value of this material.

The timing of surgery for undescended testis - a retrospective multicenter analysis.

BACKGROUND: n Germany, it is recommended that the surgical treatment of an undescended testis should be carried out between the ages of 6 months and 1 year to lower the risks of subfertility and testicular carcinoma. Although this recommendation has appeared in the German guidelines from 2007 onward, orchidopexy is still frequently performed at later ages. METHOD: We retrospectively analyzed data from seven pediatric surgical services in the German state of Baden-Württemberg on all boys who underwent orchidopexy from 2009 to 2012. We classified the timing of surgery as Age Group I (before the first birthday), Age Group II (between the first and second birthdays), and Age Group III (after the second birthday). We determined whether preoperative hormonal treatment was given and distinguished primary from secondary undescended testis. RESULTS: Among 2213 boys who underwent orchidopexy, 1850 had primary and 363 had secondary undescended testis. Of those with primary undescended testis, the percentages of boys who underwent surgery in Age Groups I, II, and III were (respectively, with 95% confidence intervals): 18.7% (17-20.6%), 24.4% (22.5-26.5%), and 57% (54.6-59.2%). A small percentage of boys in each group also received preoperative hormonal treatment. From 2009 to 2012, there was a secular trend favoring earlier orchidopexy. In 2012, 28 boys (14.2% [9.7-20.0%]) had orchidopexy in outpatient pediatric surgery practices before their first birthday, while 68 did on hospital inpatient services (40.7% [33.2-48.6%]). CONCLUSION: Most of the patients studied had surgery at a later age than recommended. Adherence to the guidelines in this respect is nonetheless relatively good in Germany compared to other countries, as studies from abroad have yielded findings that are just as bad or worse.