ALUMINA-SILICA RELATIONSHIP IN GLASS*

Assuming from a consideration of silicate minerals that aluminum should replace silicon in silicates, the authors investigated the system Na₂O-CaO-SiO₂-Al₂O₃. Densities and refractive indices have been determined and molecular refractions have been calculated. Partial molecular refractivities of Al₂O₃ indicate a coordination number of 4 for aluminum and deviate appreciably from values for compounds in which aluminum has a coordination number of 6. Interionic distances have been calculated for Si—O and Al—O. As a result of these studies, it is concluded that the aluminum atom isomorphously replaces the silicon atom in the random fetrahedral network. With this replacement, Ca⁺⁺ can increasingly replace Na⁺ in the interstices of the open structure.     

Perioperative risk factors affecting hospital stay and hospital costs in open heart surgery for patients > or = 65 years old

OBJECTIVE: Demographic changes, associated with increased demands for open heart surgery in the elderly, place increased burden on financial resources. To evaluate perioperative risk factors affecting incidence of hospital events and estimation of hospital charges, 2577 patients > or = 65 years (range 65-91), operated on from January 1991 to December 1994, were compared with a concurrent cohort of 2642 younger patients. METHODS: Statistical analysis, by surgical procedure, focused on hospital mortality, key postoperative complications affecting length of hospital stay and hospital charges. RESULTS: Overall hospital mortality was 4.7%, 3.5% in younger patients versus 6.1% in the older group (P < 0.01). Mortality was significantly lower in patients less than 65 years undergoing coronary artery bypass grafting (3% versus 5%, P < 0.01) and valve replacement (4% versus 9%, P = 0.01). Significant risk factors for hospital death in the elderly: diabetes (P < 0.01), hypertension (P < 0.01), myocardial infarction (P < 0.01) and congestive heart failure (P < 0.01). Significant postoperative events, more common in older patients, included prolonged ventilation (P < 0.01), congestive heart failure (P < 0.01), infection (P < 0.01), cerebrovascular accident (P < 0.01), and intra aortic balloon pump (P < 0.01). Incremental risk factors for morbidity in the elderly were: higher New York Heart Association class, congestive heart failure, emergent operation, and female gender. Mean length of hospital stay for the < 65 group was 15.3 versus > 19.5 days for the > 65 group (P < 0.01). Length of stay over 18 days positively correlated with increased morbidity in both age groups. For patients > or = 65 years of age, the average hospital charge for open heart surgery was 172% higher for patients with a length of stay greater than 18 days compared with 165% for patients less than 65 years of age. CONCLUSIONS: Higher operative mortality and longer length of stay in elderly patients, resulting in increased health care costs, was associated with more co-morbidities. These results suggest interventions designed to reduce congestive heart failure and other co-morbidities may improve patient's recovery and reduce costs.     

SURFACE TENSION OF GLASS AND ITS EFFECT ON CORDS*

The results of experiments with synthetic cords indicate that surface tension is the most important factor in the disappearance of cords. The viscosity relations of the glasses do not correlate with the tendency to form inhomogeneities. Fibers of higher surface tension than the base glass with which it is fused form cords, and those of lower surface tension do not. Compositions that are high in RO or A1208 tend to form inhomogeneities in glasses which have a lower content of these two constituents.     

THE PREVENTION OF DISINTEGRATION OF BLAST FURNACE LININGS1

Theories and observations on the causes of disintegration of fireclay refractories in blast furnaces are given and a process is developed for improving high iron clays for this use. The disintegration of refractories in blast furnace linings is initiated by alteration in the iron spots. Ferric oxide is reduced to ferrous oxide at 500°C and hastens the cracking of 2CO to CO₂+C₁ the carbon being retained by the lining. When Fe₂O₂ is converted to Fe₃O₄ the brick will not disintegrate.     

Psychological impact of the development of a presymptomatic test for Huntington's disease.

Examined the effects of a genetic probe that can provide individuals at risk for Huntington's disease (HD) with diagnostic information regarding this progressive genetic disorder before symptoms are exhibited. 113 at-risk HD individuals were informed about the genetic probe, and their level of anxiety was assessed. A group conference format was an effective means of providing information regarding the HD probe to a large number of at-risk families. Findings from the measure of anxiety demonstrate that the at-risk HD population is no different from a normative population or from an at-risk HD population unfamiliar with the new technology. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Wavelength Bistability in Two-Section Mode-Locked Quantum-Dot Diode Lasers

We report a two-section mode-locked quantum-dot laser with an emission wavelength that is bistable with respect to applied bias on the saturable absorber region. The two stable lasing wavelengths for this device are about 1173 and 1166 nm with a power contrast ratio of over 30 dB. The largest switchable wavelength range is 7.7 nm. The optical power and pulsewidth (6.5ps) are almost identical in the two lasing modes under optimized conditions. The operation of this laser can be explained by the interplay of the spectral-hole burning and the quantum-confined Stark effect     

Dechlorination of polychlorinated biphenyls in industrial transformer oil by radiolytic and photolytic methods

Used electrical transformer oils containing low or high concentrations of polychlorinated biphenyls (PCBs) were treated using electron, gamma, and ultraviolet radiation, and the conditions for complete dechlorination were developed. Dechlorination was determined by analysis of the inorganic chloride formed and the concentrations of remaining PCBs. Transformer oil containing approximately 95 microg g(-1) PCB (approximately 3.5 mmol L(-1) Cl) is completely dechlorinated by irradiation with 600 kGy after the addition of 10% triethylamine (TEA). Transformer oil containing >800,000 microg g(-1) PCB (17.7 mol L(-1) Cl) requires an additional solvent to prevent solidification. When this oil is diluted with 2-propanol (2-PrOH) and TEA (v/v/v, 1/79/20), complete dechlorination is achieved with a dose of 2500 kGy. Ultraviolet photolysis of the same oil/2-PrOH/TEA solutions led to 90% dechlorination after exposure for 120 h in our experimental setup. Such yields were obtained by radiolysis with a dose of 2000 kGy (300 h in our Gammacell). Replacing TEA with KOH in 2-PrOH solutions greatly increases the yield of dechlorination in both the radiolytic and the photolytic experiments, demonstrating that a chain reaction plays a role in both of these treatment methods and suggesting that both methods deserve further consideration for large-scale application.