25Mg NMR site analysis in metals and intermetallics.

Nuclear magnetic resonance (NMR) of the low abundance and low gyromagnetic ratio isotope (25)Mg, I=5/2, 2.606MHz/T, 10% abundant, is shown here to provide an informative probe for phase identification, site symmetry and site multiplicity of the intermetallic compounds which occur as strengthening precipitate phases in lightweight alloys. The intermetallics discussed here, Mg(17)Al(12), MgZn(2), Mg(2)Al(3) and Al(2)CuMg, are the final equilibrium precipitate phases in a number of Mg- and Al-based heat-treatable alloys. The (25)Mg spectra of Mg in Al-10at%Mg alloy show the progressive precipitation of Mg(2)Al(3) from Mg in solid solution as a function of annealing time at 150 degrees C. Also reported are (25)Mg spectra for CuMg(2), Mg(44)Al(15)Zn(41) and Mg(2)Sn, along with the counter atom (67)Zn and (63)Cu NMR spectra for MgZn(2) and CuMg(2). All spectra are simulated to determine nuclear interaction parameters and confirm site occupancy.

[Vital signs of hemodynamic monitoring]. / I parametri vitali del monitoraggio emodinamico.

The aim of hemodynamic monitoring in intensive care is to recognize derangements in physiologic variables, which herald the progression toward organ failure. Traditionally the term "vital signs" refers to heart rate, arterial pressure, respiratory rate and body temperature monitoring. Continuous monitoring of vital signs, is advocated, since trends are more significant than single measurements, and is still a cornerstone, in the hemodynamic evaluation of a critically ill patient. Nevertheless, the spectrum of hemodynamic derangements that can arise during intensive care unit stay is very large and often additional information, beside the vital signs, are needed to evaluate correctly the individual patient.

[Ventilator associated pneumonia]. / La polmonite da ventilatore.

Ventilator associated pneumonia (VAP) is a nosocomial lower respiratory tract infection that ensues in critically ill patients undergoing mechanical ventilation. The reported incidence of VAP varies between 9% and 68% with a mortality ranging between 33% and 71%. Two key factors are implicated in the pathogenesis of VAP: bacterial colonization of the upper digestive-respiratory tract and aspiration of oral secretions into the trachea. Preventive measurements are advocated to reduce the incidence of VAP, such as selective decontamination of the digestive tract (SDD), supraglottic aspiration and positioning. Prompt recognition and treatment of established VAP has also been demostrated to affect outcome. Therefore, the knowledge of risk factors associated with the development of VAP and the implementation of strategies to prevent, diagnose and treat VAP are mainstems in the nursing of mechanically ventilated patients.

High-temperature electron backscatter diffraction and scanning electron microscopy imaging techniques: in-situ investigations of dynamic processes.

In-situ heating experiments have been conducted at temperatures of approximately 1200 K utilising a new design of scanning electron microscope, the CamScan X500. The X500 has been designed to optimise the potential for electron backscatter diffraction (EBSD) analysis with concomitant in-situ heating experimentation. Features of the new design include an inclined field emission gun (FEG) column, which affords the EBSD geometrical requirement of a high (typically 160 degrees) angle between the incoming electron beam and specimen surface, but avoids complications in heating-stage design and operation by maintaining it in a horizontal orientation. Our studies have found that secondary electron and orientation contrast imaging has been possible for a variety of specimen materials up to a temperature of at least 900 degrees C, without significant degradation of imaging quality. Electron backscatter diffraction patterns have been acquired at temperatures of at least 900 degrees C and are of sufficient quality to allow automated data collection. Automated EBSD maps have been produced at temperatures between 200 degrees C and 700 degrees C in aluminium, brass, nickel, steel, quartz, and calcite, and even at temperatures >890 degrees C in pure titanium. The combination of scanning electron microscope imaging techniques and EBSD analysis with high-temperature in-situ experiments is a powerful tool for the observation of dynamic crystallographic and microstructural processes in metals, semiconductor materials, and ceramics.