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  • 1
    Electronic Resource
    Electronic Resource
    Electrochemical oxidation and nucleophilic addition reactions of metallocenes in electrospray mass spectrometry (1994)
    s.l. : American Chemical Society
    Analytical chemistry 66 (1994), S. 119-125 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac00073a021
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  • 2
    Electronic Resource
    Electronic Resource
    In vitro evaluation of the retention of composite fiber and stainless steel posts (2002)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of prosthodontics 11 (2002), S. 0 
    Details
    ISSN: 1532-849X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Purpose This study compared the tensile retentive strength of composite fiber-reinforced dowels luted with a resin cement to stainless steel dowels luted with zinc phosphate cement.Materials and Methods The crowns of 40 extracted human mandibular premolars were removed with a separating disc 1-mm coronal to the cementoenamel junction. The teeth were randomly divided into 4 groups (n = 10). A post space was prepared in each specimen to a depth of 9 mm, using the drill supplied by the respective manufacturer. For the stainless steel post group, 1.25-mm-diameter posts were cemented with zinc phosphate cement. For the composite fiber reinforced groups, posts with diameters of 1.00, 1.25, and 1.50 mm were luted with a Bisphenol A-Glycidyl Methacrylate (BIS-GMA) resin bonding system (Jeneric/Pentron, Wallingford, CT) according to manufacturer specifications. The specimens were stored in a sealed container with a moist environment for 24 hours, placed in a fixture in an 801 Materials Test Systems (MTS) machine (MTS Systems Corp, Minneapolis, MN), and loaded in tension at a rate of 5.0 mm/min until failure. Differences among the 4 groups were determined using a one-way analysis of variance and Tukey-B post-hoc tests (α= 0.05).Results The mean loads to failure ranged from 43.9 ± 10.4 kg for the stainless steel dowel group to 19.9 ± 5.7 kg for the composite fiber–reinforced 1.00-mm-diameter group. The stainless steel post luted with zinc phosphate cement provided significantly greater tensile resistance than all composite fiber dowel groups. The retention of the 1.00-mm composite fiber–reinforced post was significantly less than the remaining groups.Conclusions Under the conditions of this study, the stainless steel dowel luted with zinc phosphate cement provided significantly greater retention.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1532-849X.2002.00025.x
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  • 3
    Electronic Resource
    Electronic Resource
    A comparison of model-based path control algorithms for direct-drive SCARA robots (1992)
    Springer
    Journal of intelligent and robotic systems 5 (1992), S. 241-252 
    Details
    ISSN: 1573-0409
    Keywords: Adaptive control ; computed torque control ; decoupling control ; heuristic optimal control ; direct-drive robot ; measurement noise ; modelling error ; tracking control task
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Various advanced control strategies are applied to a direct-drive SCARA robot and studied in computer simulations. Besides computed torque control and direct adaptive control, heuristic optimal control, a new path control scheme for robotic manipulators, is included in the comparison study. PD control, the traditional robot control method, is used for generating a comparing baseline. While all schemes are applied for the same tracking task, the effect of modelling errors and measurement noise is considered in robot performance evaluation. Simulation results show that (1) without model errors, all advanced control schemes can achieve higher tracking accuracy than PD control; (2) with a random measurement error of 1%, computed torque and direct adaptive control methods are inferior to PD control; (3) heuristic control proves to be the most robust control scheme in case of mixed model and measurement errors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00247420
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  • 4
    Electronic Resource
    Electronic Resource
    Myxoma Virus Expresses a TNF Receptor Homolog with two Distinct Functions (2000)
    Springer
    Virus genes 21 (2000), S. 97-109 
    Details
    ISSN: 1572-994X
    Keywords: myxoma virus ; immuno-modulator ; viroceptor ; TNF receptor ; apoptosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Myxoma virus, a member of the poxvirus family of DNA viruses, encodes many virulence factors to combat and evade the host immune responses. Among the virus-encoded immuno-modulators is M-T2, a tumor necrosis factor receptor (TNF-R) homologue. M-T2 is secreted as monomeric and dimeric species that bind and inhibit rabbit TNF in a species-specific manner. Deletion analysis indicates that the anti-TNF function is mediated by the first three of four cysteine rich domains (CRDs) of M-T2. In addition, the intracellular form of M-T2 has the ability to block virus-induced apoptosis in lymphocytes, and the first two CRDs appear to be sufficient for this function. Although the mechanisms for the anti-TNF and anti-apoptotic functions of M-T2 are not yet fully defined, we postulate that these dual activities of M-T2 are mediated through different functional motifs and abrogate distinct cellular responses to virus infection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008136431036
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  • 5
    Electronic Resource
    Electronic Resource
    Transport limitation of chlorine disinfection of Pseudomonas aeruginosa entrapped in alginate beads (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 49 (1996), S. 93-100 
    Details
    ISSN: 0006-3592
    Keywords: disinfection ; chlorine ; transport ; gel bead ; biofilm ; reaction-diffusion ; Pseudomonas aeruginosa ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An artificial biofilm system consisting of Pseudomonas aeruginosa entrapped in alginate and agarose beads was used to demonstrate transport limitation of the rate of disinfection of entrapped bacteria by chlorine. Alginate gel beads with or without entrapped bacteria consumed chlorine. The specific rate of chlorine consumption increased with increasing cell loading in the gel beads and decreased with increasing bead radius. The value of an observable modulus comparing the rates of reaction and diffusion ranged from less than 0.1 to 8 depending on the bead radius and cell density. The observable modulus was largest for large (3-mm-diameter) beads with high cell loading (1.8 × 109 cfu/cm3) and smallest for small beads (0.5 mm diameter) with no cells added. A chlorine microelectrode was used to measure chlorine concentration profiles in agarose beads (3.0 mm diameter). Chlorine fully penetrated cell-free agarose beads rapidly; the concentration of chlorine at the bead center reached 50% of the bulk concentration within approximately 10 min after immersion in chlorine solution. When alginate and bacteria were incorporated into an agarose bead, pronounced chlorine concentration gradients persisted within the gel bead. Chlorine did gradually penetrate the bead, but at a greatly retarded rate; the time to reach 50% of the bulk concentration at the bead center was approximately 46 h. The overall rate of disinfection of entrapped bacteria was strongly dependent on cell density and bead radius. Small beads with low initial cell loading (0.5 mm diameter, 1.1 × 107 cfu/cm3) experienced rapid killing; viable cells could not be detected (〈1.6 × 105 cfu/cm3) after 15 min of treatment in 2.5 mg/L chlorine. In contrast, the number of viable cells in larger beads with a higher initial cell density (3.0 mm diameter, 2.2 × 109 cfu/cm3) decreased only about 20% after 6 h of treatment in the same solution. Spatially nonuniform killing of bacteria within the beads was demonstrated by measuring the transient release of viable cells during dissolution of the beads. Bacteria were killed preferentially near the bead surface. Experimental results were consistent with transport limitation of the penetration of chlorine into the artificial biofilm arising from a reaction-diffusion interaction. The methods reported here provide tools for diagnosing the mechanism of biofilm resistance to reactive antimicrobial agents in such applications as the treatment of drinking and cooling waters. © 1996 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 6
    Electronic Resource
    Electronic Resource
    Biofilm parameters influencing biocide efficacy (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 46 (1995), S. 553-560 
    Details
    ISSN: 0006-3592
    Keywords: biofilm ; disinfection ; detachment ; biofouling ; ecology ; biocide ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The influence of biofilm areal cell density, species composition, and the presence of abiotic particles on the disinfection and removal of bacterial biofilms by monochloramine was investigated. Mono- and binary population biofilms of Pseudomonas aeruginosa and Klebsiella pneumoniae were grown on stainless-steel slides in a continuous flow annular reactor. Biofilms were treated in the reactor with a pulse/step dose of 4 mg/L monochloramine for 2 h. Biofilm samples were disaggregated and assayed for colony formation on R2A agar and for total cell numbers by acridine orange direct counts. These data were used to determine apparent first order rate coefficients for the processes of disinfection and detachment. Disinfection rate coefficients exceeded detachment rate coefficients by as much as an order of magnitude and the two coefficients were poorly correlated (r = 0.272). The overall decay rate coefficient (disinfection plus detachment) depended strongly on the initial biofilm areal cell density. It displayed a parabolic dependence on cell density with a maximum near 108 cfu/cm2. This result points to multiple factors influencing biofilm susceptibility to antimicrobial challenge. Decay rates of K. pneumoniae measured in binary population biofilms were comparable with those measured in monopopulation biofilms (p = 0.61). P. aeruginosa decayed more slowly in biofilsm dominated by K. pneumoniae (p = 0.028), indicating some interaction between species. The presence of kaolin and calcium carbonate particles in the biofilm reduced disinfection efficacy. © 1995 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260460608
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