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  • Polymer and Materials Science  (7)
  • Engineering  (4)
  • Altitude acclimatization  (2)
  • Annonaceae  (2)
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Years
Keywords
  • 1
    ISSN: 1420-9071
    Keywords: Sylvaticin ; acetogenin ; Rollinia sylvatica ; Annonaceae ; brine shrimp ; cytotoxicity ; insecticidal ; striped cucumber beetle ; European corn borer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Sylvaticin (I), a new tetrahydroxy annonaceous acetogenin with nonadjacent tetrahydrofuran rings, has been isolated from the dried fruits ofRollinia sylvatica St. Hil. (Annonaceae). This compound is extremely cytotoxic to human tumor cells and shows promising insect control properties.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1420-9071
    Keywords: Gigantecin ; acetogenins ; Goniothalamus giganteus ; Annonaceae ; brine shrimp ; antimitotic ; cytotoxic ; crown gall tumors ; potato disc assay ; 9 ASK
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Gigantecin (I), a novel tetrahydroxy-di-tetrahydrofuran fatty acid γ-lactone (acetogenin), was isolated from an ethanolic extract of the stem bark ofGoniothalamus giganteus Hook. f., Thomas (Annonaceae), by means of activity-directed fractionation (brine shrimp lethality test). This new compound is extremely cytotoxic to human tumor cells, inhibits crown gall tumors on potato discs, and is active in an assay designed to detect antimitotic agents (9 ASK).
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    European journal of applied physiology 73 (1996), S. 202-209 
    ISSN: 1439-6327
    Keywords: Peripheral chemoreceptors ; Hypoxic ventilatory response ; Altitude acclimatization ; High altitude
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Hypoxic ventilatory response (HVR) was examined before and after acclimatization to high altitude. Transient hyperoxic switches according to Dejours's technique were used to examine the contribution of HVR to the hyperpnoea of increasing exercise intensities. Ten mountaineers were exposed to hypoxia (oxygen fraction in inspired gas,F 1O2 = 0.11, 79 mmHg) before the expedition and after return from altitude (56 days, 30 days at 4900 m or higher). After 25-min breathing hypoxic gas, the subjects performed a maximal cycle ergometer test (increments 50 W per 5 min). Respired gases and ventilation $$(\dot V_E )$$ were analysed breath-by-breath, partial pressure of oxygen (PO2) and oxygen saturation (SO2) were measured in capillary blood. The HVR was tested by switching two breaths to anF 1O2 of 1.0. The nadir of $$\dot V_E $$ after the switch was measured (decrease in ventilation, D $$\dot V_E $$ ). The HVR was expressed as the D $$\dot V_E $$ at a PO2 of 40 mmHg (D $$\dot V_{E40} $$ ) and the D $$\dot V_E $$ versus decrease ofSO2 (D $$\dot V_E $$ /[100 −SO2]). The HVR estimated by D $$\dot V_{E40} $$ increased from 19.9 to 28.01 · min−1 (median,P = 0.013). The HVR expressed as D $$\dot V_E $$ /(100 −SO2) at rest was no different before and after acclimatization (0.89 and 0.86 l · min−1 · %−1, respectively) and during exercise it did not change before the expedition (0.831 · min−1 %−1). However, D $$\dot V_E $$ /(100 −SO2) increased significantly with exercise intensity after the expedition (1.61 l · min−1 · %−1 at 200 W). The changes of D $$\dot V_E $$ versusSO2 as well as of D $$\dot V_E $$ versus $$\dot V_E $$ were steeper after the expedition than before. In summary, after return from 30 day at high altitude, an increased HVR was observed. The augmentation of HVR was evident at higher exercise intensities and we suggest that this reflects a change in sensitivity of the peripheral chemoreflex loop.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1439-6327
    Keywords: Hypoxia ; Exercise ; Rebreathing Alveolar-arterial difference ; Altitude acclimatization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Studies were made of pulmonary diffusion capacity and oxygen transport before and after an expedition to altitudes at and above 4900 m. Maximum power (P max) and maximal oxygen uptake (VO 2max) were measured in 11 mountaineers in an incremental cycle ergometer test (25W · min−1) before and after return from basecamp (30 days at 4900 m or higher). In a second test, cardiac output (Q c) and lung diffusion capacity of carbon monoxide (D L,CO) were measured by acetylene and CO rebreathing at rest and during exercise at low, medium and submaximal intensities. After acclimatization, VO2max and P max decreased by 5.1% [from 61.0 (SD 6.2) to 57.9 (SD 10.2) ml·kg−1, n.s.] and 9.9% [from 5.13 (SD 0.66) to 4.62 (SD 0.42) W·kg−1, n.s.], respectively. The maximal cardiac index and DL,co decreased significantly by 15.6% [14.1 (SD 1.41) 1·min−1 · m−2 to 11.9 (SD 1.44)1·min−1 m−2, P〈0.05] and 14.3% [85.9 (SD 4.36)ml·mmHg−1 min−t to 73.6 (SD 15.2) ml · mmHg−1 -min−1, P〈0.05], respectively. The expedition to high altitude led to a decrease in maximal Q c, oxygen uptake and DL,CO. A decrease in muscle mass and capillarity may have been responsible for the decrease in maximal Qc which may have resulted in a decrease of D L,CO and an increase in alveolar-arterial oxygen difference. The decrease in D L,CO especially at lower exercise intensities after the expedition may have been due to a ventilation-perfusion mismatch and changes in blood capacitance. At higher exercise intensities diffusion limitation due to reduced pulmonary capillary contact time may also have occurred.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 23-42 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A very simple and reliable error estimator has recently been developed for problems of linear elasticity.1 This leads naturally toa predication of an h-mesh refinement required for a given accuracy and with a suitable mesh generator2 for an efficient adaptive process. In this paper we extend the methodology developed previously to incompresible plastic flow of metals or polymers using the ‘flow formulation’ approach.3The examples of application include steady state extrusion problems for which exact solutions are available and hence allow the efficiency of the error estimates to be tested as well as more complex problems of upsetting in which the mesh is updated. It is found that the estimator performs well under various circumstances and provides an economical adaptive process.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 2191-2202 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: This note reports numerical experiments on the efficiency of simple error estimates derived earlier1 applied to incompressible mixed or related penalty type formulations. The rate of convergence and performance of various mixed elements is compared. Numerical results from a driven cavity and an incompressible elastic problem demonstrate that the T6B1/3D and T6/3C elements give a faster rate of convergence than the T6/1D element. However, in the case of a plane extrusion analysis (stronger singularity), the rate of convergence for the T6B1/3D element drops and is inferior to that of the T6/1D, while the T6/3C element still proves superior to the other two elements.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electroanalysis 3 (1991), S. 909-916 
    ISSN: 1040-0397
    Keywords: Indium ; potentiometry ; membrane ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The potentiometric anion responses of polymeric membranes doped with various indium (III)-porphyrin structures are examined. The appropriate membranes are prepared by incorporating 1.0 wt % of the In(III)-porphyrins in plasticized poly(vinyl chloride) films. When such membranes are incorporated within standard ion selective electrode bodies, the resulting electrodes display non-Hofmeister anion selectivity, with a particularly enhanced and super-Nernstian response to chloride. Among those porphyrins investigated, membranes doped with chloro(octaethylporphyrinato)indium(III) yield the largest and most reproducible potentiometric anion responses. These same membrane electrodes exhibit negligible response to protons (or hydroxide) in the range of pH 4.5-9.0. When utilized as a flow-injection detector in conjunction with a protein diluent/buffer stream, the In(III)-porphyrin based electrodes may be used to determine chloride levels in human serum samples.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 31 (1993), S. 939-951 
    ISSN: 0887-6266
    Keywords: permeability of gases in 6FDA polyimides ; polyimides, 6FDA, permeation of gases in ; selectivity of 6FDA polyimides for gas separations ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Mean permeability coefficients for CO2, O2, N2, and CH4 in seven types of 6FDA polyimides with branched or extended diamine moieties were determined at 35.0°C (95.0°F) and at pressures up to 10.5 atm (155 psia). In addition, solubility coefficients for CO2, O2, N2, and CH4 in six of these polyimides were determined at 35.0°C and at 6.8 atm (100 psia). Mean diffusion coefficients for the six gas/polyimide systems were calculated from the permeability and solubility data. The relationships between the chemical structure of the polyimides, some of their physical properties (glass transition temperature, mean interchain spacing, specific free volume), and their gas permeability, diffusivity, and solubility behavior are discussed. The 6FDA polyimides studied here exhibit a considerably lower selectivity for the CO2/CH4 and O2/N2 gas pairs than 6FDA polyimides with short and stiff aromatic diamines with comparable CO2 and O2 permeabilities. © 1993 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 21 (1987), S. 247-261 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Bone-particle-impregnated bone cement specimens (up to 30% by weight) were characterized by various test methods. The experimental bone cement showed decreased crack propagation rates and increased Young's modulus, while the ultimate tensile strength and impact strength were decreased. The viscosity could be adjusted by adding initiators lost when substituting the PMMA powder with bone particles. The present study warranted fur-ther in vivo experiments on the possibility of tissue ingrowth for which the new bone cement was developed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 25 (1991), S. 141-156 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: To evaluate an experimental inorganicbone-particle-impregnated bone cement, canine hip prostheses were implanted in dogs using a regular bone cement on one side and the experimental bone cement on the other. In a preliminary feasibility study, bone ingrowth into the resorbed bone-particle spaces was established 3 months after implantation in three dogs. In a more detailed study, twenty-eight (28) dogs were divided in four groups to delineate the effects of time on the phenomena of bony ingrowth. One month after implantation, active bone ingrowth into the bone cement was obvious. By 3 months postimplantation, the ingrowth appeared to have traversed the thickness of the bone-particle-impregnated cement. By the fifth month, most of the interconnected inorganic bone particles were replaced by new bone. At the end of a year, the ingrown bone was mature and negligible new bone activity was present. Biomechanical pushout tests closely corroborated the histologic observations. The maximum shear strength of the cement/bone interface of the experimental side reached 3.6 times that of the control side at 5 months postimplantation. No further improvements were seen at 12 months postimplantation. A viable bone/cement interface may result in a better orthopedic implant fixation system by combining the advantages of both cement for immediate rigidity and biological ingrowth for longterm stability.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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