Measurement of size-dependent composition variations for gamma prime (γ') precipitates in an advanced nickel-based superalloy.

Energy-dispersive X-ray (EDX) spectroscopy in the scanning transmission electron microscope (STEM) has been used to demonstrate the presence of size-dependent compositional variation for L12-structured Ni3Al-type gamma-prime (γ') precipitates within a commercial RR1000 Ni-based superalloy. This semi-quantitative elemental analysis has been achieved using electrochemical extraction of the γ' precipitates from the γ matrix. The applicability of this approach to size-dependent compositional analysis of precipitates was confirmed by a comparison of the size distribution for the extracted precipitates with those present in traditional electropolished foil specimens in the size range 20-250nm. By applying suitable thickness-dependent absorption-corrections we have demonstrated that the composition of γ' precipitates in our material depends on the size of the precipitate in the range of 5nm to 3µm. In particular, the Al content was observed to increase in smaller γ' precipitates while Ti and Ta contents are constant for all sizes of precipitate. Hf was observed to be present only in the largest precipitates. This type of local compositional information provides invaluable input to assess the accuracy of microstructural modelling for these complex alloys and provides new evidence supporting the importance of anti-site diffusion.

Feasible without subsidy? Overnight respite for Alzheimer's.

The Fairmont Hospital Overnight Respite Unit was an innovative program developed as the third part of a continuum of care for clients with Alzheimer's disease. The other parts were home care and case management and a day care and resource center. The continuum was innovative in that it represented a joint effort between a county hospital and two community-based non-profit organizations. This program operated for 2 years, 9 months and was closed due to a lack of long-term, ongoing funding.

Pulmonary function of the reserpine and isoproterenol models of cystic fibrosis.

Two experimental animal models exhibiting functional and morphologic changes of exocrine glands similar to those seen in patients with cystic fibrosis (CF) have been reported in the rat: chronic stimulation with reserpine (Martinez et al. 1973 Pediatr. Res. 9:463, 470) and chronic stimulation with isoprenaline (Sturgess and Reid 1973 Br. J. Exp. Pathol. 54:388). We have studied the pulmonary function of these models induced by injecting rats subcutaneously with reserpine (RES, 0.5 mg/kg/day), isoproterenol (ISO, 25 mg/kg/day), or saline (Con, 1.0 ml/kg/day) for 6 days. Plethysmographic measurements were made for functional residual capacity (FRC), airways resistance (Raw), specific airways conductance (sGaw), phase difference between air flow rate and mean alveolar pressure (PD), frequency of breathing (f), and tidal volume (VT) of the anesthetized rats. In the RES and ISO rats, the FRC, Raw and f were not different from Con values. The PD was greater and the VT was less than Con values (p less than 0.05). The results of both studies indicate uneven ventilation (increased PD) and penduluft (decreased VT) consistent with maldistribution of resistance and/or compliances of the peripheral airways and/or alveolar compartments. These physiologic effects can be related to the morphologic changes reported for the airways of rats under chronic adrenergic stimulation (ISO) and expected for rats under chronic catecholamines depletion (RES). Since peripheral airways involvement is usually the earliest pulmonary lesion found in CF, these studies indicate that the RES and ISO models may be representative of the early pulmonary involvement of CF.

Legionella wadsworthii species nova: a cause of human pneumonia.

A new species of Legionella that caused pneumonia in a patient with chronic lymphocytic leukemia has been characterized. The Legionella wadsworthii species nova is proposed for this bacterium. The type strain is Wadsworth 81-716A (American Type Culture Collection 33877). The new species differs phenotypically from L. pneumophila in that the predominant cellular fatty acid is methyl-12-methyltetradecanoic acid (a-15:0) rather than methyl-14-methylpentadecanoic acid (i-16:0), and in its failure to react with L. pneumophila antiserum. The clinical illness caused by L. wadsworthii was not apparently different from that seen with other legionella infections, except for prolonged fever and slow resolution of pulmonary infiltrates.