Non Linear Electronic and Optical Processes in Fullerene Thin Films

In this study the current voltage characteristics of C60 thin film sandwich structures fabricated by vacuum deposition on indium tin oxide (ITO) with an aluminium top electrode are presented and discussed. A strongly non-linear behaviour and a sharp increase in the device conductivity was observed at relatively low voltages, at both room and low temperatures (30K). At room temperature the system is seen to collapse. In situ Raman measurements indicate that the collapse is the result of a solid state reduction of the fullerene thin film to a polymeric state. The high conductivity state was seen to be stable at elevated voltages and low temperatures. This state is seen to be reversible with the application of high voltages. At these high voltages the C60 film was seen to sporadically emit white light at randomly localized points analogous to the much-documented electroluminescence in single crystals. Moreover, the evidence suggests that this highly conducting species maybe similar in nature to a high intensity optically excited species

Linear Electronic and Optical Processes in Fullerene Thin Films

The electrical properties of C60 have been extensively studied in both the solid and solution phases. The vibrational spectroscopy of C60 is predominantly molecular in character. However electronic spectroscopy reveals features, which are specific to the solid. These features have been attributed to intermolecular charge transfer states. The relative importance of these inter – and intramolecular processes in terms of their contribution to the electronic transport is discussed. Cyclic voltammetry is employed to generate charged molecular species, which also contribute to the conduction process and comparisons to optical excited states species are drawn. The cyclic voltammetry was monitored in situ with vibrational spectroscopy so as to observe any shifts in the C60 spectrum due to charging. The current voltage characteristics of thin film sandwich structures fabricated by vacuum are then presented and discussed. A strongly non-linear behaviour is observed, a sharp increase in the device conductance being observed at relatively low voltages at both room temperature and at 20K. The room temperature IV curves confirm a lattice collapse upon charging. The high conductivity state is however observed to be stable at low temperature

Mechanical factors in the prediction of integrity of the gastrojejunal anastomosis in ex-vivo RYGB models.

BACKGROUND Surgical staplers represent one of the important instruments in modern surgery. Laparoscopic Roux-en-Y gastric bypass is one of the most commonly performed bariatric procedures. Various techniques have been described for performing gastrojejunal (GJ) anastomosis, including linear stapled anastomosis (LSA), circular stapled anastomosis (CSA) and hand-sewn anastomosis (HSA). OBJECTIVES An ex-vivo porcine-based experiment was designed to compare the mechanical integrity of the GJ anastomosis among the 3 different techniques by measuring burst pressure (BP). SETTING Laboratory-based study conducted at the clinical skills laboratory at Birmingham Heartlands Hospitals, Birmingham, United Kingdom. METHODS Porcine stomachs and small bowels were used to create a GJ model. Four GJ anastomosis models each were created using circular stapler (CSA group) and hand-sewn techniques (HSA group). Stomach and small bowel thickness were recorded. BP was measured by sequential injections of methylene-blue diluted saline until a leak was detected. Total volume until leak is recorded. Compliance (C) was calculated using the formula C = ΔP/ΔV. RESULTS Results from our previous experiment for the LSA group are included. One model was excluded from the CSA and the HSA groups due to technical errors. Results were presented as mean ± standard deviation. Total volume in LSA, CSA, and HSA groups was 60 ± 4.08 mL, 73.67 ± 3.22 mL, and 51.67 ± 20.21 mL, respectively. BP in LSA, CSA, and HSA groups was 18 ± 4.69 mm Hg, 20.33 ± 5.77 mm Hg, and 9.67 ± 3.79 mm Hg, respectively. There was a statistically significant difference in BP among the 3 groups (P = .033; Kruskal-Wallis test). C in LSA, CSA, and HSA were 3.50 ± .88 mm Hg/mL, 3.78 ± .85 mm Hg/mL, and 5.39 ± 1.34 mm Hg/mL, respectively (P = .064). CONCLUSION BP was higher in CSA and LSA groups compared with the HSA group, suggesting a mechanically stronger anastomosis. Despite the lack of statistical significance, higher BP recorded in the CSA group than in the LSA group suggests better anastomotic integrity

Delaying surgery for patients with a previous SARS-CoV-2 infection

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