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  • 1
    ISSN: 1432-1041
    Keywords: Hypokalaemia ; Fenoterol ; Salbutamol ; exercise
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: The effect of β2-adrenoceptor agonist-induced hypokalaemia on cardiac arrhythmias might be exacerbated during exercise, especially in patients with more compromised airway function. Methods: To evaluate the effect of β2-adrenoceptor agonists on plasma potassium and cardiopulmonary function during exercise, two identical submaximal treadmill exercise tests were performed, at least 48 h apart, by 13 patients with moderate to severe COPD (11 men and 2 women, mean age 66 y, mean FEV1/FVC ratio 48.9 (2.8)%) 30 min after they had received nebulised fenoterol or salbutamol (2 mg). The experiment was done as a randomised, double-blind, crossover trial after an initial baseline study with vehicle (0.45% saline). Plasma potassium concentration, spirometry and the degree of breathlessness (Borg scale) were measured before treatment and immediately after exercise; oxygen saturation, QTc interval and cardiac rhythm were monitored continuously before, during and for 30 min after exercise. Results: After the saline control, exercise caused an increase in Borg rating (of 4.9), a premature ventricular contractions (VPC) (2.8 beats/min), and a fall in oxygen saturation (-6.7%), but no significant change in plasma potassium (+0.04 mEq·dl−1), FEV1 or QTc interval. Inhalation of fenoterol and salbutamol did not affect QTc interval, Borg scale or VPC frequency at rest, but significantly increased the duration of exercise undertaken to reach the submaximal levels (786 s, versus 783 s) compared to the vehicle control. Following exercise, plasma potassium fell after fenoterol by 0.2 mEq·dl−1 and it increased after salbutamol by 0.1 mEq·dl−1 compared to baseline levels. Plasma potassium after exercise was significantly lower after fenoterol (3.2 mEq·dl−1) compared to the saline control (3.7 mEq · dl−1) and salbutamol (3.6 mEq · dl−1). Neither fenoterol nor salbutamol had any significant effect on the change in FEV1, oxygen saturation, Borg scale, frequency of VPCs or QTc interval during or after exercise compared to the saline control. Conclusion: When compared to salbutamol 2 mg, fenoterol 2 mg caused more marked hypokalaemia but no significant difference in cardiopulmonary response in patients with COPD during exercise.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1041
    Keywords: Key words Hypokalaemia ; Fenoterol ; Salbutamol; exercise
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: The effect of β2-adrenoceptor agonist-induced hypokalaemia on cardiac arrhythmias might be exacerbated during exercise, especially in patients with more compromised airway function. Methods: To evaluate the effect of β2-adrenoceptor agonists on plasma potassium and cardiopulmonary function during exercise, two identical submaximal treadmill exercise tests were performed, at least 48 h apart, by 13 patients with moderate to severe COPD (11 men and 2 women, mean age 66 y, mean FEV1/FVC ratio 48.9 (2.8)%) 30 min after they had received nebulised fenoterol or salbutamol (2 mg). The experiment was done as a randomised, double-blind, crossover trial after an initial baseline study with vehicle (0.45% saline). Plasma potassium concentration, spirometry and the degree of breathlessness (Borg scale) were measured before treatment and immediately after exercise; oxygen saturation, QTc interval and cardiac rhythm were monitored continuously before, during and for 30 min after exercise. Results: After the saline control, exercise caused an increase in Borg rating (of 4.9), a premature ventricular contractions (VPC) (2.8 beats/min), and a fall in oxygen saturation (−6.7%), but no significant change in plasma potassium (+ 0.04 mEq⋅dl−1), FEV1 or QTc interval. Inhalation of fenoterol and salbutamol did not affect QTc interval, Borg scale or VPC frequency at rest, but significantly increased the duration of exercise undertaken to reach the submaximal levels (786 s, versus 783 s) compared to the vehicle control. Following exercise, plasma potassium fell after fenoterol by 0.2 mEq⋅dl−1 and it increased after salbutamol by 0.1 mEq⋅dl−1 compared to baseline levels. Plasma potassium after exercise was significantly lower after fenoterol (3.2 mEq⋅dl−1) compared to the saline control (3.7 mEq⋅dl−1) and salbutamol (3.6 mEq⋅dl−1). Neither fenoterol nor salbutamol had any significant effect on the change in FEV1, oxygen saturation, Borg scale, frequency of VPCs or QTc interval during or after exercise compared to the saline control. Conclusion: When compared to salbutamol 2 mg, fenoterol 2 mg caused more marked hypokalaemia but no significant difference in cardiopulmonary response in patients with COPD during exercise.
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  • 3
    ISSN: 1432-0649
    Keywords: 82.30 ; 82.50
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The reaction of NO2 with isobutane, induced by 488 nm laser radiation, to form 2-nitro-2-methylpropane has been investigated and the results computer-modeled according to two possible reaction mechanisms. The first scheme involves the direct abstraction of H from isobutane by vibronically excited NO2 (NO 2 *Δ ), and the second, abstraction by an intermediate NO3 radial produced by NO 2 *Δ +NO2. The modeling results strongly support the NO 2 *Δ scheme as the dominant reaction mechanism.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 39 (1986), S. 55-59 
    ISSN: 1432-0649
    Keywords: 82.30 ; 82.50
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The 488 nm laser-induced reaction of NO2 with CO has been investigated and the results computer-modeled. Two reaction mechanisms were considered:1) the direct reaction of vibronically excited NO2 (NO 2 * † ) with CO to form CO2, and 2), the reaction of an intermediate NO3 radical formed by the reaction of NO 2 * † with NO2 followed by NO3+CO→NO2+CO2. The modeling results strongly support the former as the dominant mechanism.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 39 (1986), S. 61-63 
    ISSN: 1432-0649
    Keywords: 82.30 ; 82.50
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract 1-Nitroadamantane was produced by irradiating a solution of adamantane and NO2 in CCl4 with the visible lines (457.9–514.5 nm) of an argon-ion laser. At these wavelengths NO2 does not photodissociate to form O atoms, and thus the nitration reaction must be initiated by another species, probably vibronically excited NO2 (NO 2 *† ). The intensity of the laser enables the reaction to be carried out in a reasonable length of time, despite the strong quenching of NO 2 *† by CCl4.
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  • 6
    ISSN: 1432-0649
    Keywords: 82.50 ; 82.65NZ
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The photodesorption and photodecomposition pathways of dimethylgold hexafluoroacetylacetonate, DMG (hfac), adsorbed on a cooled quartz substrate is reported for 222-nm KrCl excimer laser radiation. The time-of-flight (TOF) of neutral photoproducts, desorbed from the surface of the gold film formed during the experiment, were analyzed under collisionless conditions by a differentially-pumped mass spectrometer. Extensive dissociation of adsorbed DMG (hfac) into DMG and the hfac ligand was observed. The ligand was found to recombine with a CH3 radical on the surface. Translational energy distributions for the detected species were obtained by deconvoluting the TOF curves into a self-consistent set of Maxwell-Boltzmann distributions for the desorbed parent molecule, laser-induced decomposition products, and surface recombination reaction products. The implications of these results for the mechanistic details of the low-pressure, laser-assisted organometallic deposition of DMG(hfac) are discussed.
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  • 7
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Earth and Planetary Science Letters 32 (1976), S. 236-248 
    ISSN: 0012-821X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Geosciences , Physics
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  • 8
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: In this work, a 1 m long Sasaki-type elliptically polarizing undulator (EPU) prototype with 5.6 cm period length is used to examine the mechanical design feasibility as well as magnetic field performance. The magnetic field characteristics of the EPU5.6 prototype at various phase shifts and gap motion are described. The field errors from mechanical tolerances, magnet block errors, end field effects and phase/gap motion effects are analysed. The procedures related to correcting the field with the block position tuning, iron shimming and the trim blocks at both ends are outlined.
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  • 9
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report results of our growth and characterization of GaN films using low-pressure chemical vapor epitaxy with a new nitrogen source, hydrazoic acid (HN3). This growth technique allows for low-temperature deposition, low III/V ratios, and increased deposition rates (up to ∼2–3 μm/h). The deposited films show Ga:N atomic ratios of 1±0.25 based on our x-ray photoelectron spectroscopy analyses, and the He(II) UPS (ultraviolet photoelectron spectroscopy) spectra compare favorably with the semi-ab initio calculations for the GaN valence bands and with the reported UPS data for single crystal GaN films. X-ray and Raman spectra show deposited films crystallized in the expected wurtzite structure. We find these epitaxial films to be efficient light emitters in the blue or yellow region of the spectrum, depending upon growth conditions. Our photoluminescence time-decay kinetics confirm the excitonic nature of the blue emission. Lastly, far infrared time-domain spectroscopy shows the low carrier concentration of this material. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 10
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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