Microstructural Characterization of TiC–White Cast-Iron Composites Fabricated by In Situ Technique

High-chromium white cast-iron specimens locally reinforced with TiC–metal matrix composites were successfully produced via an in situ technique based on combustion synthesis. Powder mixtures of Ti, Al, and graphite were prepared and compressed to fabricate green powder compacts that were inserted into the mold cavity before the casting. The heat of the molten iron causes the ignition of the combustion reaction of the reactant powders, resulting in the formation of the TiC by self-propagating high-temperature synthesis. The microstructure of the resultant composites and the bonding interfaces was characterized by scanning electron microscopy and energy dispersive spectroscopy (SEM/EDS), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The microstructural results showed a good adhesion of the composite, suggesting an effective infiltration of the metal into the inserted compact, yet a non-homogeneous distribution of the TiC in the martensite matrix was observed. Based on the results, the in situ synthesis appears to be a great potential technique for industrial applications.

Soft XAS as an in situ technique for the study of heterogeneous catalysts

Perspectives on the use of soft X-ray absorption spectroscopy as a tool to rationally develop new heterogeneous catalysts.

In Situ Treatment of Branch Renal Artery Aneurysms With Pantaloon Vein Graft

Introduction: The optimal method of operative management of complex renal artery aneurysms (RAAs) involving distal branches (BRAAs) remains unclear. When more than 1 artery is involved within the BRAA, endovascular techniques are not advisable and an ex vivo approach is often preferred. In this study, we introduce an alternative surgical in situ technique to treat BRAAs. Methods and Surgical Technique: Five aneurysms involving the main or second-order bifurcation of the renal artery (RA) were treated in 4 patients at our institute between November 2012 and January 2017. The treatment of the BRAAs was based on resection of the aneurysm wall and reconstruction with autologous Pantaloon vein graft (PVG): a “Y-shaped” bypass created on-bench with autogenous great saphenous vein. Sequential clamping/reperfusion of the kidney allows to reduce renal function impairment. Results: No perioperative mortality or morbidity was observed, including none nephrectomy. In all the cases, aneurysms were treated with an in situ technique as previously planned. All the grafts were patent at the follow-up time (mean 64.1 ± 11.7 months). Renal function was preserved in all the cases. Vascularization of the renal parenchyma was satisfactory both on arterial echo Doppler and contrast-medium ultrasound in all the cases. Average cross-clamping times of the main RA and of a single branch RA were 15.8 ± 1.7 and 17.7 ± 4.6 minutes, respectively. Mean total operating time was 266.3 ± 18.9 minutes. Conclusion: The PVG with sequential clamping applied in the surgical treatment of BRAAs permits to reduce the ischemic effects to the renal parenchyma. To our knowledge, these are the first cases described in which BRAAs are treated with a PVG and our experience suggests that it is a feasible technique, with good long-term results and without severe adverse events recorded.