Preliminary studies of the alteration of a granite by an artificial hydrothermal system

Solution channels in quartz, microcline, and plagioclase of a granite were produced by exposure of the rock to an artificial hydrothermal system. Electron microprobe analyses, beam-scanning photographs, and element profiles show that the mineral grains are homogeneous and unaltered within a few micrometers of the channels. The channels, which are 3 to 7 ..mu.. in diameter, appear to have formed by removal of material in solution. In the sample material, no new minerals produced by alteration or deposition were detected by microprobe analysis. The apparent absence of such alteration products (e.g., clays) may be due to (1) sample preparation which removed fine-grained alteration products during polishing; or (2) concentrations of such minerals in such small amounts that they are below the limits of detectability with the microprobe. The granite is seen to be preferentially attacked by the hydrothermal solution along grain boundaries and cracks. Similar solution effects are observed in amphibolites exposed to the artificial hydrothermal system. Plagioclase crystals in the amphibolite are partially dissolved so that delicate porous boxwork structures remain

Graft factors as determinants of postoperative delirium after liver transplantation

AbstractPost-operative delirium (POD) is a frequent complication after surgery, occurring in 15–20% of patients. POD is associated with a higher complications rate and mortality. Literature on POD after liver transplantation (LT) is limited, with the few available studies reporting an incidence of 10–47%. The aim of this study was analyzing pattern, risk factors and clinical impact of POD after LT. Data on donor and recipient characteristics, postoperative course and POD of consecutive adult LT recipients from March 2016 to May 2018 were prospectively collected and retrospectively analyzed. Risk factors for POD were analyzed using univariable logistic regression and Lasso regression. Kaplan–Meier method was used for survival analysis. 309 patients underwent LT during study period; 3 were excluded due to perioperative death. Incidence of POD was 13.4% (n = 41). The median day of onset was 5th (IQR [4–7]) with a median duration of 4 days (IQR [3–7]). Several risk factors, related to the severity of liver disease and graft characteristics, were identified. Graft macrovesicular steatosis was the only factor independently associated with POD at multivariable analysis (OR 1.27, CI 1.09–1.51,p = 0.003). POD was associated with a higher rate of severe postoperative complications and longer intensive care unit and hospital stay, but did not significantly impact on patient and graft survival. Incidence of POD after LT is comparable to that observed after general surgery and graft factors are strongly associated with its onset. These results help identifying a subset of patients to be considered for preventive interventions.</jats:p