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  • 1995-1999  (25)
  • Chemistry  (20)
  • biomonitoring  (3)
  • Muscle model  (2)
  • Organic Chemistry  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Changes induced by eccentric training on force-velocity relationships of the elbow flexor muscles (1995)
    Springer
    European journal of applied physiology 72 (1995), S. 183-185 
    Details
    ISSN: 1439-6327
    Keywords: Muscle model ; Eccentric training ; Surface electromyography.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of this study was to examine the effects of a short term eccentric training period on force-velocity relationships of the elbow flexor muscles. From a muscle model, the maximal shortening velocity VO(x) and the af parameter which varies according to the curvature of the force-velocity relationship of the muscle were determined. Sixteen volunteer subjects divided into 2 groups participated in this study (Group Eccentric GE, n=8 . Group Control GC, n=8). The subjects performed, on an isokinetic ergometer, 2 maximal concentric elbow flexions at different angular velocities (60, 120, 180; 240, 300, 360 °s−1) and held maximal and submaximal isometric actions at an elbow flexion angle of 90°. Under isometric conditions, myoelectrical activity (EMG) of the biceps was recorded and quantified as a RMS value. All tests were performed before and after training sessions. Training was conducted 3 times a week for 4 weeks by the GE, and included 6×5 eccentric actions with a load of 100% of 1 RM. After training and for the GE, the af parameter and Vo(x) increased significantly (p〈0.05). These changes were accompanied by a significant increase (p〈0.05) of the RMS value of the maximal isometric action. This evolution towards faster characteristics for the elbow flexor muscles after training could be partly due to nervous adaptation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00964136
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  • 2
    Electronic Resource
    Electronic Resource
    Viscosity of the elbow flexor muscles during maximal eccentric and concentric actions (1996)
    Springer
    European journal of applied physiology 73 (1996), S. 157-162 
    Details
    ISSN: 1439-6327
    Keywords: Damping coefficient ; Muscle model ; Electromyogram
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of the present study was to estimate the damping coefficient (B factor) of the elbow flexor muscles during both eccentric and concentric muscle actions. We used a muscle model consisting of a viscous damper associated in parallel with a contractile component, both in series with an elastic component. The viscous damper allowed the concentric loss and the eccentric gain of force to be modelled. Eight volunteer subjects performed maximal eccentric and concentric elbow movements on an isokinetic dynamometer at angular velocities of 0.52, 1.04 and 2.09 rad·s−1. Torques at an elbow joint angle of 90° were recorded. Electromyogram (EMG) signals from the belly of the right elbow flexor and from the long head of the triceps brachia muscles were recorded using two pairs of bipolar surface electrodes. The root mean square (rms) of the EMG was determined. Eccentric and concentric rms were not significantly different (P〉0.05). The B factor was higher in the concentric than in the eccentric conditions (P〈0.05), and, whatever the muscle action type it decreased as the velocity increased. These results indicated that the concentric loss and the eccentric gain of force were attributable to the behaviour of the contractile machinery. Furthermore, whatever the exact cause of loss and gain of tension, our study showed that the total effect can be modelled by the viscous damper of a three-component muscle model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00262825
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  • 3
    Electronic Resource
    Electronic Resource
    Tree bark as a bioindicator of air pollution in Navarra, spain (1997)
    Springer
    Water, air & soil pollution 98 (1997), S. 381-387 
    Details
    ISSN: 1573-2932
    Keywords: air pollution ; bioindicator ; biomonitoring ; tree bark
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract During a two year research period from 1992 to 1993, samples of different species of trees were taken in 17 forest stands located in Navarra, Spain. From these samples, bark extracts were prepared in which the pH and the conductivity were measured. The health of the sampling trees was also evaluated by determining the degree of defoliation and decoloration of the canopies. The bark tissue analysis revealed the presence of an environmental acidity gradient that decreased from NW to SE. This coincides with the location of important sources of pollution and their course of transport and dispersion. On the other hand, in the samples ofQuercus ilex a significant correlation between the pH and the defoliation levels (P≤0.01, r=0.62) was found. This fact reveals the potential usefulness of tree bark as a health bioindicator of trees.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02047045
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  • 4
    Electronic Resource
    Electronic Resource
    Tree bark as a bioindicator of air pollution in Navarra, Spain (1997)
    Springer
    Water, air & soil pollution 98 (1997), S. 381-387 
    Details
    ISSN: 1573-2932
    Keywords: air pollution ; bioindicator ; biomonitoring ; tree bark
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract During a two year research period from 1992 to 1993, samples of different species of trees were taken in 17 forest stands located in Navarra, Spain. From these samples, bark extracts were prepared in which the pH and the conductivity were measured. The health of the sampling trees was also evaluated by determining the degree of defoliation and decoloration of the canopies. The bark tissue analysis revealed the presence of an environmental acidity gradient that decreased from NW to SE. This coincides with the location of important sources of pollution and their course of transport and dispersion. On the other hand, in the samples of Quercus ilex a significant correlation between the pH and the defoliation levels (P≤0.01, r = 0.62) was found. This fact reveals the potential usefulness of tree bark as a health bioindicator of trees.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026431211784
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  • 5
    Electronic Resource
    Electronic Resource
    Monitoring of the Phytosanitary State of Navarra's Forests, Spain (1998)
    Springer
    Environmental monitoring and assessment 50 (1998), S. 217-231 
    Details
    ISSN: 1573-2959
    Keywords: biomonitoring ; damage inventory ; forest assessment ; forest decline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Between 1988 and 1993 six surveys on the condition of forests in Navarra (North Spain) were carried out. The results, relating to 408 trees in 17 sampling points, showed that the overall percentage of damaged trees increased from 2.86% in 1988 to 18.6% in 1993, which indicates a general large-scale deterioration of forest condition. Among the most common groups of trees, the most severely affected species were Quercus faginea, Quercus robur and Pinus sylvestris. Furthermore, it was observed that defoliation and discoloration processes did not occur randomly between stand trees, but the trees that were damaged one year (1992) were more predisposed to suffer damage in the next year (1993).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005879728924
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  • 6
    Electronic Resource
    Electronic Resource
    Design and development of a vasoactive intestinal peptide analog as a novel therapeutic for bronchial asthma (1995)
    New York : Wiley-Blackwell
    Biopolymers 37 (1995), S. 57-66 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Analogs of vasoactive intestinal peptide (VIP) were synthesized and screened as bronchodilators with the ultimate goal of enhancing the potency and extending the duration of action of the native peptide. Several design approaches were applied to the problem. First, the amino acid residues required for receptor binding and activation were identified. A model of the active pharmacophore was developed. With knowledge of the secondary structure (NMR) of the peptide, various analogs were synthesized to stabilize α-helical conformations. Having achieved a level of enhanced bronchodilator potency, our approach then concentrated on identification of the sites of proteolytic degradation and synthesis of metabolically-stable analogs. Two primary cleavage sites on the VIP molecule were identified as the amide bonds between Ser25-Ile26 and Thr7-Asp8. This information was used to synthesize cyclic peptides which incorporated disulfide and lactam ring structures. Analog work combined the best multiple-substitution sites with potent cyclic compounds which resulted in identification of a cyclic lead peptides. This compound, Ro 25-1553, exhibited exceptionally high potency, metabolic stability, and a long duration of action and may be an effective therapeutic for the treatment of bronchospastic diseases. © 1994 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360370203
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  • 7
    Electronic Resource
    Electronic Resource
    The Reactivity of Complexes of Nickel(0) and Platinum(0) Containing Benzyne and Related Small-Ring Alkynes (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1029-1042 
    Details
    ISSN: 0009-2940
    Keywords: Nickel ; Platinum ; Aryne complexes ; Cyclohexyne complexes ; Insertions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparation and reactivities of cyclohexyne and aryne complexes of platinum(0) and nickel(0) are reviewed. These complexes undergo insertions with unsaturated molecules such as alkenes, alkynes, isocyanides, CO and CO2. In the case of the nickel- benzyne complexes, consecutive insertions are observed with alkynes, leading to substituted naphthalenes with good regioselectivities. A possible mechanism for these double insertions, based on a combination of steric and electronic factors, is discussed in detail.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300803
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  • 8
    Electronic Resource
    Electronic Resource
    Residence time distribution in three-phase monolith reactor (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 649-657 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The residence time distribution of the liquid phase within a three-phase monlith reactor is determined using tracer studies. The actual liquid residence time in the monolith, relevant for reactor design purposes, is calculated from overall residence time measurements using deconvolution by Fourier transform. The liquid-phase residence time decreases as liquid or gas flow rates increase, but the reactor Peclet number remains approximately constant. The residence time distribution and calculated values of the Peclet number reveal that the liquid phase is substantially well-mixed. Comparison with results from experiments in a single glass capillary reveals that the monolith channels become predominantly liquid-filled, particularly as the liquid flow rate becomes a significant fraction of the total flow rate.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690410321
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  • 9
    Electronic Resource
    Electronic Resource
    Monolith froth reactor: Development of a novel three-phase catalytic system (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 337-345 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The monolith froth reactor, involving two-phase flow and a monolith catalyst, is developed. The flow within monolith channels, consisting of trains of gas bubbles and liquid slugs, is produced by forming a two-phase froth in a chamber immediately below the bottom of the monolith. The froth then flows upward into the monolith channels through pressure forces, which differs from previous methods since it may be carried out for a commercial-scale reactor. Because the liquid film which develops between the gas phase and the surface of the catalyst is extremely thin, two-phase flow within a monolith can provide reaction rates which are near their intrinsic values. Catalytic oxidation of aqueous phenol over copper oxide supported on γ-Al2O3 is used as a model reaction for investigating reactor performance. Generation of a froth is confirmed by visual inspection; the average bubble size is approximately that predicted by a force balance. The effect of externally controllable process variables (liquid and gas flow rates, temperature, and pressure) on the rate of phenol oxidation was investigated. Reaction rate increases with temperature or pressure increase and decreases with gas flow rate increase, achieving a maximum with respect to liquid flow rate. The activation energy calculated from the apparent reaction rate measured in the monolith froth reactor is similar to that of intrinsic value, suggesting minimal mass-transfer limitations.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690410215
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  • 10
    Electronic Resource
    Electronic Resource
    Catalytic supercritical water oxidation: Stability of Cr2O3 catalyst (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 1995-2004 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Supercritical water oxidation has become a well-known treatment technology for conversion of aqueous wastes. By introducing a catalyst, higher conversion and selectivity to carbon dioxide can be achieved at a lower temperature and at shorter residence times. The stability of chromium oxide in supercritical water was studied to determine the feasibility of using catalysts during supercritical water oxidation. Various process variables, including oxygen and water concentrations, fluid flow rate, and temperature were found to affect the reactivity of the chromium oxide catalyst. Under these conditions, chromium was present in the reactor effluent as chromic acid, H2CrO4. The visual observation of the catalyst after the completion of the experiments suggested that a reaction front moved along the length of the reactor. A rate expression, based on Langmuir-Hinshelwood kinetics, with dissociative chemisorption of oxygen on a hydrated chromium oxide surface, was proposed. The model, developed based on this rate expression and the continuity equation for the fluid phase, was consistent with the experimental results.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420720
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