Severe myocardial dysfunction and coronary revascularization

Severe myocardial dysfunction, characterized by global hypokinesis, or akinetic areas with hypokinesis of the remaining wall, and a very low ejection fraction (EF), has been considered to be a contraindication for coronary revascularization (CABG). However, myocardial scintigraphy and echo-stress data have shown that hypo- or akinetic areas can regain their contractility. Therefore, we expanded the indications for CABG, and performed operations even upon patients who were waiting for a heart transplant. Between January 1993 and June 1995, among 352 patients who underwent CABG, 85 had highly depressed left ventricular function. Their resting EF was lower than 0.35, and in 27 it was lower than 0.25. Viable areas of myocardium were found in all of the patients through the combination of scintigraphy and dobutamine-echocardiography: these areas depended on significant coronary lesions. The mean age of the patients was 48.2 years (range 33-62 years); angina was present in 62 patients. A mean of 3.1 grafts/patient were implanted; enoximone was used in all but 5 patients upon weaning from cardiopulmonary bypass; intra-aortic balloon pump was used in 9 cases. Operative mortality was 10.6% (9 patients), due to low-output syndrome in 5, acute myocardial infarction in 2, cerebral damage in 1, and respiratory failure in 1. At the 6-month follow-up, EF was improved in all but 7 patients, in whom it remained unchanged. Scintigraphic and echocardiographic tests revealed good function in most of the areas that had been previously recognized as hypo- or akinetic. These results suggest that the indications for standard myocardial revascularization can be expanded, and a promising option can be offered to patients who may otherwise be destined to wait for an uncertain transplantation.     

Silk fibroin nanofibers electrospun on glass fiber as a potential device for solid phase microextraction

The electrospinning technique was applied to coat fused silica fibers with regenerated silk fibroin (RSF) nanofibers, aiming to build a device applicable for solid phase microextraction analysis. The device was characterized by attenuated total reflectance infrared spectroscopy, thermal analyses (differential scanning calorimetry and thermogravimetric analysis), and scanning electron microscopy, and employed to extract/desorb isopropyl alcohol (IPA) from the headspace of an IPA aqueous solution. The electrospun coating proved to be thermally stable up to 250°C, even after 4 h of exposure to this temperature. A 2² factorial experimental design was used to evaluate the flow rate of the polymer solution and the distance between capillary tip and collector on the mean RSF fiber diameter. A low flow rate (0.20 mL h^?1) and large capillary tip‐to‐collector distance (12 cm) yielded fibers with mean diameter of (304 ± 46 nm). The nanofibers were heated to 250°C, simulating the conditions in the injector of a gas chromatograph (GC). In these conditions, the RSF nanofibers were found not to melt even after 4 h of exposure to heat, although slight structural damage was detected. Preliminary assays using the as‐constructed device built under optimized electrospinning conditions (0.20 mL h^?1 and 12 cm) were performed in a GC by contact with the headspace of a 50 ppm IPA solution to determine the extraction and desorption times. The results indicated that the extraction process stabilized after 20 min of contact with the headspace of the IPA solution. The desorption process was complete after 10 min at 140°C. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41717.     

Proposal of a modal-geometrical-based master nodes selection criterion in modal analysis

Dynamic condensation techniques, used to simplify the dynamic representation of complex mechanical systems, and experimental modal identifications, in terms of number of sensors and their location, are deeply influenced by the selection of the degrees of freedom.The paper deals with a methodology for selecting physical nodes involved in model reduction or in experimental sensor location, named modal-geometrical selection criterion (MoGeSeC). It is based on the geometrical properties of the structure and on mode shape displacements, evaluated through finite element models or measured data set.By means of the well-known system equivalent reduction expansion process (SEREP) approach applied with MoGeSeC methodology, the ill conditioning of mass and stiffness matrices of the reduced model is minimized with a very low computational cost.In order to test MoGeSeC performance, some optimal nodes placement techniques, based on the maximization of the independence of modal properties or on energetic approaches, have been investigated. Finally, by means of a tailored iterative procedure, the best and the worst master node selections are performed on a particular model.Modal properties and ill conditioning of mass and stiffness matrices of reduced models are computed for several cases of different kind (1D-beam, 2D-shell, and 3D-solid elements). Finally an FE model of an exhaust pipeline, characterised by different constraint conditions, is considered and experimentally tested in order to validate the proposed methodology.     

Nanostructure of buried interface layers in TiO₂ anatase thin films grown on LaAlO₃ and SrTiO₃ substrates

TiO(2) anatase thin films grown by pulsed laser deposition are investigated by high resolution transmission electron microscopy and high angle annular dark field scanning transmission electron microscopy. The analyses provide evidence of a peculiar growth mode of anatase on LaAlO(3) and SrTiO(3) characterized by the formation of an epitaxial layer at the film/substrate interface, due to cationic diffusion from the substrate into the film region. Pure TiO(2) anatase growth occurs in both specimens above a critical thickness of about 20 nm. The microstructural and chemical characterization of the samples is presented and discussed in the framework of oxide interface engineering.