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  • 1
    ISSN: 1432-1238
    Keywords: Critical care ; Ethics ; Resuscitation orders ; Advance directives ; Life support withdrawal ; Prognosis ; Severity of illness index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Objectives To examine the frequency of limiting (withdrawing and withholding) therapy in the intensive care unit (ICU), the grounds for limiting therapy, the people involved in the decisions, the way the decisions are implemented and the patient outcome. Design Prospective survey. Ethical approval was obtained. Setting ICUs in tertiary centres in London and Cape Town. Patients All patients who died or had life support limited. Interventions Data collection only. Results There were 65 deaths out of 945 ICU discharges in London and 45 deaths out of 354 ICU discharges in Cape Town. Therapy was limited in 81.5% and 86.7% respectively (p=0.6) of patients who died. The mean ages of patients whose therapy was limited were 60.2 years and 51.9 years (p=0.014) and mean APACHE II scores 18.5 and 22.6 (p=0.19) respectively. The most common reason for limiting therapy in both centres was multiple organ failure. Both medical and nursing staff were involved in most decisions, which were only implemented once wide consensus had been reached and the families had accepted the situation. Inotropes, ventilation, blood products, and antibiotics were most commonly withdrawn. The mean time from admission to the decision to limit therapy was 11.2 days in London and 9.6 days in Cape Twon. The times to outcome (death in all patients) were 13.2 h and 8.1 h respectively. Conclusions Withdrawal of therapy occurred commonly, most often because of multiple organ failure. Wide consensus was reached before a decision was made, and the time to death was generally short.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1238
    Keywords: Key words Critical care ; Ethics ; Resuscitation orders ; Advance directives ; Life support withdrawal ; Prognosis ; Severity of illness index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Objectives: To examine the frequency of limiting (withdrawing and withholding) therapy in the intensive care unit (ICU), the grounds for limiting therapy, the people involved in the decisions, the way the decisions are implemented and the patient outcome. Design: Prospective survey. Ethical approval was obtained. Setting: ICUs in tertiary centres in London and Cape Town. Patients: All patients who died or had life support limited. Interventions: Data collection only. Results: There were 65 deaths out of 945 ICU discharges in London and 45 deaths out of 354 ICU discharges in Cape Town. Therapy was limited in 81.5% and 86.7% respectively (p=0.6) of patients who died. The mean ages of patients whose therapy was limited were 60.2 years and 51.9 years (p=0.014) and mean APACHE II scores 18.5 and 22.6 (p=0.19) respectively. The most common reason for limiting therapy in both centres was multiple organ failure. Both medical and nursing staff were involved in most decisions, which were only implemented once wide consensus had been reached and the families had accepted the situation. Inotropes, ventilation, blood products, and antibiotics were most commonly withdrawn. The mean time from admission to the decision to limit therapy was 11.2 days in London and 9.6 days in Cape Town. The times to outcome (death in all patients) were 13.2 h and 8.1 h respectively. Conclusions: Withdrawal of therapy occurred commonly, most often because of multiple organ failure. Wide consensus was reached before a decision was made, and the time to death was generally short.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The cationic polymerization of butadiene with several Friedel-Crafts catalysts has been described. Aluminum chloride and chlorosulfonic acid are active catalysts at -75°. The rate of polymerization at -75° is much faster than at the higher temperatures. Except for boron trifluoride etherate, which catalyzes the polymerization at -30°, the other catalysts (sulfuric acid, fuming sulfuric acid, stannic chloride, and boron trifluoride hydrate) produce appreciable amounts of polymer only at 0° or higher.The effect of variables, such as catalyst concentration, catalyst solvent, dilution, reaction time, etc., differs with each individual catalyst. In some cases, results were not conclusive due to lack of reproducibility. It was found that the presence of moisture is mainly responsible for this lack of reproducibility. Traces of water promote the polymerization with stannic chloride or boron trifluoride etherate, but inhibit the polymerization when an ethyl bromide solution of aluminum chloride is used as catalyst.Rubberlike polyhutadienes can be obtained with all catalysts except sulfuric and fuming sulfuric acids. However, the physical properties of these polymers show that the molecular weight is very low and that the polymer is not suitable as a rubber. Polymers ranging from viscous liquids to hard, brittle solids have also been obtained. In general, the solubility of the polymers is low. Approximately 60% of the butadiene enters the polymer chain by 1,4 addition.The copolymerization of butadiene and styrene at -75° with an ethyl bromide solution of aluminum chloride has also been studied. At conversions between 20 and 30% a soluble, rubberlike copolymer having a low molecular weight is formed. An insoluble, brittle polymer is obtained a t higher conversions.The soluble, cationic copolymer has a characteristic ultraviolet absorption curve which is different from that of GR-S. It has a styrene content of approximately 50% by weight which demonstrates that the styrene is more active in cationic copolymerization than is butadiene.
    Additional Material: 16 Tab.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0272-8397
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: This study examines for the first time how matrix crosslinking affects the composite physical and mechanical properties of a graphite fiber reinforced PMR polyimide composite during long-term isothermal aging. Unidirectional composite specimens of Celion 6000/PMR-P1 were isothermally exposed at 288°C in air for various time periods up to 5000 h. The matrix crosslink densities were estimated from the kinetic theory of rubber elasticity and shifts in the glass transition temperatures (Tgs). The Tg, coefficient of thermal expansion, density, weight loss, moisture absorption, and elevated temperature flexural and interlaminar shear properties were also determined. Several linear relationships were found between the matrix crosslink density and composite physical and mechanical properties. The Tg, initial weight loss and density, and elevated temperature interlaminar shear strength increase with an increase in crosslink density. Conversely, the initial moisture absorption and coefficient of thermal expansion decrease with increasing crosslink density. As expected, the elevated temperature flexural strength and modulus show no direct correlations with crosslink density. Further, after achieving the highest matrix crosslink density, several of the composite properties begin to decrease rapidly. These findings suggest that time-temperature dependent nature of attaining the maximum matrix crosslinking is closely linked to the onset of the composite property degradation. Though much more work is needed, a fundamental understanding of the relationships between matrix crosslinking and composite physical and mechanical property can provide a scientific basis for the prediction of the extent of composite service life not only for PMR polyimides but also for other thermosetting matrix resins, such as epoxies and bismaleimides.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 16 (1978), S. 75-79 
    ISSN: 0360-6384
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
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