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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Surgical endoscopy and other interventional techniques 13 (1999), S. 658-661 
    ISSN: 1432-2218
    Keywords: Key words: Ergonomics — Intracorporeal knotting — Motion analysis — Needle drivers — Rocker handle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: The design of the handle on instruments for endoscopic surgery determines comfort and efficiency of use by the surgeon. This applies particularly to needle drivers. Methods: A novel rocker handle was designed to provide holding comfort and intuitive function. This rocker handle was compared with a finger-loop handle in a study involving 10 surgeons who tied a total of 360 intracorporeal surgeons' knots in a random sequence. The end points in this study were the execution time, knot quality, and motion analysis parameters of the surgeon's elbow and shoulder joints. Results: Intracorporeal surgeon's knots tied with the rocker-handle driver exhibited a better knot quality, although this was not significant (p= 0.097). A significant improvement in the knot quality score (KQS) was observed between the first and the second sessions (p= 0.045) with the rocker handle, whereas no significant learning effect was observed for the finger-loop handle. During intracorporeal knot tying, the angular velocity at the elbow and shoulder joints was consistently lower with the rocker handle, suggesting that more controlled movements are enacted by the surgeon with this handle. Discomfort from finger-loop pressure on the thumb was reported by 3 of 10 surgeons with the finger-loop handle, whereas no discomfort was reported for the rocker handle. Conclusions: The new rocker handle improves the quality of task performance by eliminating discomfort and reducing angular velocities at the shoulder and elbow joints during use.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 12 (1970), S. 541-560 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A continuous symbiotic algal-bacterial system was developed consisting essentially of a mixed Chlorella-activated sludge culture which would efficiently remove nutrients from wastewater under aerobic conditions without supplementary aeration. Oxygen decline data were fitted to a mathematical model used to predict respiratory rates, photosynthetic oxygenation, and steady-state oxygen concentrations. Stable relative biological populations and a dissolved oxygen concentration of about 2 mg/1 were maintained during steady-state operation with daily harvesting of excess biomass. Respiratory and physiological relationships indicated that the carbon dioxide-oxygen balance is a primary control that governs the steady-state operation of a symbiotic algal-bacterial culture. The close association of the algae and bacteria resulted in an algal-bacterial floc with settled rapidly yielding a clear supernatant.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Blends of poly(2,6-dimethyl-l,4-phenylene oxide) and copolymers of styrene and maleic anhydride have been characterized by differential scanning calorimetry, dynamic mechanical analysis, and tensile measurements. Differential scanning calorimetry measurements indicate a single broadened glass transition for each blend of a 8 wt.% maleic anhydride copolymer, P(S-8MA), but two glass transitions when the copolymer composition is 14 wt.% MA, P(S-14MA). The glass transition temperatures of the former blends follow a sigmoidal dependence on blend composition, which is explained on the basis of evidence for phase separation from their dynamic mechanical tan 8 spectra. Tensile moduli of both blends reach a maximum at intermediate blend compositions; however, large-strain mechanical properties are highly dependent on blend compatibility and the method of sample preparation. The more homogeneous P(S-8MA) blends yield at low-to-intermediate copolymer compositions but fail in a brittle mode at higher compositions. All heterogeneous P(S-14MA) blends undergo brittle failure, but comparison of experimetal values of ultimate stress and strain with predictions from empirical relationships developed for composites indicate that interfacial adhesion is strong in these systems.
    Additional Material: 28 Ill.
    Type of Medium: Electronic Resource
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