Application of online near infrared spectroscopy to study the kinetics of anionic polymerization of butadiene

Wooden elements may be subjected to mechanical, environmental or biological alterations during their service life. The most susceptible parts of wood structural members are the exposed surfaces since they are subjected to ageing, weathering and/or decay. Knowledge of the influence of weathering factors and polymer degradation mechanisms is essential for understanding the weathering process of wood. The goal of this study was to investigate the degradation of thin wooden samples exposed to short-term weathering. Tests were performed through the European summer (July), which according to previous research is considered as the most severe period for weathering of wood micro-sections. Fourier transform near infrared spectroscopy was used for evaluation of chemical changes of wood samples. Three approaches for data evaluation are presented in this paper: (1) direct spectral interpretation, (2) a concept for calculation of a weathering index Wind and (3) kinetics of lignin changes in relation to the exposure direction for selected wavelengths. Observation of the effects of weathering will allow better understanding of the degradation process. The southern exposure site was slightly more affected by weathering than other sites. Results of this research will be used for future determination of the weather-dose response model and could be essential for predicting the future performance of timber facade elements.

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Muscle capillary blood flow kinetics estimated from pulmonary O2 uptake and near-infrared spectroscopy

Journal of Applied Physiology ◽

10.1152/japplphysiol.00907.2004 ◽

2005 ◽

Vol 98 (5) ◽

pp. 1820-1828 ◽

Cited By ~ 115

Author(s):

Leonardo F. Ferreira ◽

Dana K. Townsend ◽

Barbara J. Lutjemeier ◽

Thomas J. Barstow

Keyword(s):

Blood Flow ◽

Infrared Spectroscopy ◽

Near Infrared Spectroscopy ◽

Lactate Threshold ◽

Time Course ◽

Near Infrared ◽

Primary Component ◽

Capillary Blood ◽

Capillary Blood Flow ◽

Kinetics Of

The near-infrared spectroscopy (NIRS) signal (deoxyhemoglobin concentration; [HHb]) reflects the dynamic balance between muscle capillary blood flow (Q̇cap) and muscle O2 uptake (V̇o2m) in the microcirculation. The purposes of the present study were to estimate the time course of Q̇cap from the kinetics of the primary component of pulmonary O2 uptake (V̇o2p) and [HHb] throughout exercise, and compare the Q̇cap kinetics with the V̇o2p kinetics. Nine subjects performed moderate- (M; below lactate threshold) and heavy-intensity (H, above lactate threshold) constant-work-rate tests. V̇o2p (l/min) was measured breath by breath, and [HHb] (μM) was measured by NIRS during the tests. The time course of Q̇cap was estimated from the rearrangement of the Fick equation [Q̇cap = V̇o2m/(a-v)O2, where (a-v)O2 is arteriovenous O2 difference] using V̇o2p (primary component) and [HHb] as proxies of V̇o2m and (a-v)O2, respectively. The kinetics of [HHb] [time constant (τ) + time delay [HHb]; M = 17.8 ± 2.3 s and H = 13.7 ± 1.4 s] were significantly ( P < 0.001) faster than the kinetics of V̇o2 [τ of primary component (τP); M = 25.5 ± 8.8 s and H = 25.6 ± 7.2 s] and Q̇cap [mean response time (MRT); M = 25.4 ± 9.1 s and H = 25.7 ± 7.7 s]. However, there was no significant difference between MRT of Q̇cap and τP-V̇o2 for both intensities ( P = 0.99), and these parameters were significantly correlated (M and H; r = 0.99; P < 0.001). In conclusion, we have proposed a new method to noninvasively approximate Q̇cap kinetics in humans during exercise. The resulting overall Q̇cap kinetics appeared to be tightly coupled to the temporal profile of V̇o2m.

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