Time resolved fluorescence and energy transfer analysis of Nd(3+)-Yb (3+)-Er (3+) triply-doped Ba-Al-metaphosphate glasses for an eye safe emission (1.54 microm).

This paper reports on the preparation and systematic analysis of energy transfer mechanisms in Nd(3+)-Yb(3+)-Er(3+) co-doped new series of barium-alumino-metaphosphate glasses. The time resolved fluorescence of Nd(3+) in triply doped Ba-Al-metaphosphate glasses have revealed that, Yb(3+) ions could function as quite efficient bridge for an energy transfer between Nd(3+) and Er(3+) ions. As a result, a fourfold emission enhancement at 1.54 mum of Er(3+) ions has been achieved through an excitation of (4)F(5/2) level of Nd(3+) at 806 nm for the glass having 3 mol% Yb(3+) with an energy transfer efficiency reaching up to 94%. Decay of donor (Nd(3+)) ion fluorescence has been analyzed based on theoretical models such as direct energy transfer model (Inokuti-Hirayama) and migration assisted energy transfer models (Burshtein's hopping and Yokota-Tanimoto's diffusion). The corresponding energy transfer parameters have been evaluated and discussed. Primarily, electrostatic dipole-dipole (s approximately 6) interactions are found to be responsible for the occurrence of energy transfer process in theses glasses.

Preparation of colourless phosphate glass by stabilising higher Fe[II] in microwave heating.

Iron impurity in raw material remains a major challenge in producing colourless glass. In this investigation, we report microwave (MW) heating capable of altering Fe-redox ratio (Fe2+/∑Fe) enabling preparation of colourless phosphate glass. The effect of Sn concentration in retention of Fe[II] in glass melted in MW was compared with conventional glasses. Colourimetric study developing Fe2+-ferrozine colour complex reveals Fe-redox ratio ≥0.49 required to obtain colourless phosphate glass. In microwave heating, addition of 1 wt.% Sn metal powder can impart the desired effect whereas addition of 1.9 wt.% Sn metal powder is required in conventional heating. The correlation equation of Fe-redox ratio with concentration of Sn metal is found to be different in microwave and conventional heating. Thus, exploiting this different redox changes in MW heating optical properties can be tailored. Preservation of higher Fe[II] in MW melted glass is also confirmed by XPS and TGA. 31P MAS NMR spectra suggest that transition from cross linked ultra phosphate to linear polymer metaphosphate network in incorporation of Sn is found different in glass prepared adopting microwave irradiation. 27A1 MAS NMR spectra suggest higher relative content of Al6+ in glass obtained from MW heating. Energy consumption analysis revels 3.4 kWh in MW heating while 14 kWh in conventional glass melting using resistance heating. Further, glass melting in MW can be completed within 2 h unlike ~5 h needed in conventional. MW heating plays a significant role in improving properties to make colourless phosphate glass in addition to significant energy and time saving.

Natural history of multifocal solitary fibrous tumors of the pleura: a 25-year follow-up report.

We report this case with "multifocal solitary fibrous tumors of the pleura," which recurred at different sites in the left pleura at different time intervals over a span of 25 years, finally exhibiting features of malignant transformation. This patient was first seen in 1978, when she was 58 years of age, for episodic attacks of hypoglycemia and a mass occupying the entire left hemithorax. The operative findings and histologic appearance were that of a solitary fibrous tumor.

Thoracoabdominal injuries in the elderly: 25 years of experience.

BACKGROUND: The present study was conducted to determine the clinical characteristics and outcome of hospitalized elderly patients with thoracic and thoracoabdominal injuries. METHOD: This is a longitudinal, nonblinded study using established standard of care of patients with penetrating and blunt chest trauma. From April 1972 to August 1997, 5,702 patients were hospitalized for chest injuries. Out of these patients, 171 (3%) were aged 65 or above. Of these patients, 96 (56%) had blunt trauma (group 1)--motor vehicle accident in 83 (86%) and falls in 13 (14%). The remaining 75 (44%) patients had penetrating injuries (group 2)--gunshot wounds in 47 (63%) and stab wounds in 28 (37%). RESULTS: Of the blunt trauma patients, 45% (43/96), and 15% (11/75) of the penetrating trauma patients were managed by observation alone; the remainder required surgical procedures. The overall mortality was 10% (17/171), of which mortality among penetrating and blunt trauma to the chest were 12% (9/75) and 8% (8/96), respectively. Of eight deaths due to blunt trauma, six had multiple (four or more) rib fractures. There were no deaths among the 54 patients who were simply observed, and none of them required surgery at a later date. Complication rate among the survivors was 12.3%, with only 0.4% being infectious. CONCLUSIONS: Mortality was highest among the elderly with penetrating chest trauma. Mortality was high because of cardiac and great vessel injuries in group 2, whereas multiple rib fractures and brain injuries were the higher cause of mortality in group-1 patients. Infectious complications were low among the survivors.