Analysis of wood thermal degradation using 2D correlation of near infrared and visible-light spectroscopy

2019 ◽  
Vol 27 (5) ◽  
pp. 354-369
Author(s):  
Siti Hanifah Mahdiyanti ◽  
Tetsuya Inagaki ◽  
Satoru Tsuchikawa
Keyword(s):  
Thermal Degradation ◽  
Visible Light ◽  
Near Infrared ◽  
Color Change ◽  
Correlation Spectroscopy ◽  
Color Measurement ◽  
Temperature Superposition ◽  
Time Temperature Superposition ◽  
Visible Light Spectroscopy ◽  
Cielab Color

Wood changes its properties, especially color, as a result of thermal degradation. In this study, change in wood properties due to thermal degradation have been studied using the nondestructive test methods of near infrared spectroscopy, CIELAB color measurement, visible-light spectroscopy, and Arrhenius time–temperature superposition. Arrhenius time–temperature superposition allowed analysis of near infrared and visible-light spectra, and color parameters to predict thermal degradation and color change of wood at 120–180℃ for 6 min to nine months duration. Two-dimensional correlation spectroscopy for the complementary analysis of near infrared and visible-light spectroscopy was applied to investigate chemical changes during wood thermal degradation that cause the observed color change. Visible-light spectroscopy with CIELAB color measurement was used to obtain information on color changes, and near infrared spectroscopy was applied in the measurement of chemical changes during thermal degradation. Changes in spectral intensities in 2D correlation spectroscopy indicated that different chemical components are responsible for color change during heat treatment and accelerated aging of wood. With dry-thermal treatment, the hemicellulose content decreased following a color change, whereas cellulose and lignin/extractives decreased with hygro-thermal treatment.

Kinetics of muscle deoxygenation and microvascular Po2 during contractions in rat: comparison of optical spectroscopy and phosphorescence-quenching techniques

2012 ◽  
Vol 112 (1) ◽  
pp. 26-32 ◽  
Author(s):  
Shunsaku Koga ◽  
Yutaka Kano ◽  
Thomas J. Barstow ◽  
Leonardo F. Ferreira ◽  
Etsuko Ohmae ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Visible Light ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Fiber Type ◽  
Type I ◽  
Phosphorescence Quenching ◽  
Mean Response Time ◽  
Muscle Deoxygenation ◽  
Visible Light Spectroscopy

The overarching presumption with near-infrared spectroscopy measurement of muscle deoxygenation is that the signal reflects predominantly the intramuscular microcirculatory compartment rather than intramyocyte myoglobin (Mb). To test this hypothesis, we compared the kinetics profile of muscle deoxygenation using visible light spectroscopy (suitable for the superficial fiber layers) with that for microvascular O2 partial pressure (i.e., PmvO2, phosphorescence quenching) within the same muscle region (0.5∼1 mm depth) during transitions from rest to electrically stimulated contractions in the gastrocnemius of male Wistar rats ( n = 14). Both responses could be modeled by a time delay (TD), followed by a close-to-exponential change to the new steady level. However, the TD for the muscle deoxygenation profile was significantly longer compared with that for the phosphorescence-quenching PmvO2 [8.6 ± 1.4 and 2.7 ± 0.6 s (means ± SE) for the deoxygenation and PmvO2, respectively; P < 0.05]. The time constants (τ) of the responses were not different (8.8 ± 4.7 and 11.2 ± 1.8 s for the deoxygenation and PmvO2, respectively). These disparate (TD) responses suggest that the deoxygenation characteristics of Mb extend the TD, thereby increasing the duration (number of contractions) before the onset of muscle deoxygenation. However, this effect was insufficient to increase the mean response time. Somewhat differently, the muscle deoxygenation response measured using near-infrared spectroscopy in the deeper regions (∼5 mm depth) (∼50% type I Mb-rich, highly oxidative fibers) was slower (τ = 42.3 ± 6.6 s; P < 0.05) than the corresponding value for superficial muscle measured using visible light spectroscopy or PmvO2 and can be explained on the basis of known fiber-type differences in PmvO2 kinetics. These data suggest that, within the superficial and also deeper muscle regions, the τ of the deoxygenation signal may represent a useful index of local O2 extraction kinetics during exercise transients.

scholarly journals The Role of Scale Adjustment in Color Change Evaluation

Instruments ◽  
2019 ◽  
Vol 3 (3) ◽  
pp. 42 ◽  
Author(s):  
Gueli ◽  
Pasquale ◽  
Politi ◽  
Stella
Keyword(s):  
Color Change ◽  
High Reliability ◽  
Research Work ◽  
Color Space ◽  
Color Difference ◽  
Color Measurement ◽  
Cielab Color Space ◽  
Archaeological Excavations ◽  
Cielab Color

The aim of this research work was to assess the influence of different scale adjustment conditions on both color measurement and color difference quantification and, in particular, to determine the best procedure to follow for a high-reliability protocol. This issue is very important in the Cultural Heritage field and, above all, in color measurement, which is carried out at different times during conservation and restoration campaigns or during archaeological excavations. Color change evaluation, performed by way of spectrophotometric measurements under different scale adjustment procedures on selected samples represented by colored reflectance standards and colored paintings, aimed to obtain results not only on ideal samples (certified standards) but also on real case studies (paintings). The study was conducted by focusing on the coordinates of the CIELAB color space and, in particular, on the calculation of the ΔE*ab quantity. The results show the introduction of nonsystematic variation with different scale adjustment procedures independent of materials and hue.

Continuous, Noninvasive, and Localized Microvascular Tissue Oximetry Using Visible Light Spectroscopy

2004 ◽  
Vol 100 (6) ◽  
pp. 1469-1475 ◽  
Author(s):  
David A. Benaron ◽  
Ilian H. Parachikov ◽  
Shai Friedland ◽  
Roy Soetikno ◽  
John Brock-Utne ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Ventricular Fibrillation ◽  
Visible Light ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Normal Range ◽  
Hemoglobin Oxygen Saturation ◽  
Tissue Oximetry ◽  
Visible Light Spectroscopy ◽  
Saturation Difference

Background The authors evaluated the ability of visible light spectroscopy (VLS) oximetry to detect hypoxemia and ischemia in human and animal subjects. Unlike near-infrared spectroscopy or pulse oximetry (SpO2), VLS tissue oximetry uses shallow-penetrating visible light to measure microvascular hemoglobin oxygen saturation (StO2) in small, thin tissue volumes. Methods In pigs, StO2 was measured in muscle and enteric mucosa during normoxia, hypoxemia (SpO2 = 40-96%), and ischemia (occlusion, arrest). In patients, StO2 was measured in skin, muscle, and oral/enteric mucosa during normoxia, hypoxemia (SpO2 = 60-99%), and ischemia (occlusion, compression, ventricular fibrillation). Results In pigs, normoxic StO2 was 71 +/- 4% (mean +/- SD), without differences between sites, and decreased during hypoxemia (muscle, 11 +/- 6%; P &lt; 0.001) and ischemia (colon, 31 +/- 11%; P &lt; 0.001). In patients, mean normoxic StO2 ranged from 68 to 77% at different sites (733 measures, 111 subjects); for each noninvasive site except skin, variance between subjects was low (e.g., colon, 69% +/- 4%, 40 subjects; buccal, 77% +/- 3%, 21 subjects). During hypoxemia, StO2 correlated with SpO2 (animals, r2 = 0.98; humans, r2 = 0.87). During ischemia, StO2 initially decreased at -1.3 +/- 0.2%/s and decreased to zero in 3-9 min (r2 = 0.94). Ischemia was distinguished from normoxia and hypoxemia by a widened pulse/VLS saturation difference (Delta &lt; 30% during normoxia or hypoxemia vs. Delta &gt; 35% during ischemia). Conclusions VLS oximetry provides a continuous, noninvasive, and localized measurement of the StO2, sensitive to hypoxemia, regional, and global ischemia. The reproducible and narrow StO2 normal range for oral/enteric mucosa supports use of this site as an accessible and reliable reference point for the VLS monitoring of systemic flow.

Integration of Atomistic Simulation with Experiment Using Time−Temperature Superposition for a Cross-Linked Epoxy Network

2019 ◽  
Author(s):  
Ketan Khare ◽  
Frederick R. Phelan Jr.
Keyword(s):  
Master Curve ◽  
Glassy State ◽  
Superposition Principle ◽  
Quantitative Comparison ◽  
Time Shift ◽  
Data Sets ◽  
Epoxy Network ◽  
Temperature Superposition ◽  
Time Temperature Superposition ◽  
Time Temperature Superposition Principle

<a></a><a>Quantitative comparison of atomistic simulations with experiment for glass-forming materials is made difficult by the vast mismatch between computationally and experimentally accessible timescales. Recently, we presented results for an epoxy network showing that the computation of specific volume vs. temperature as a function of cooling rate in conjunction with the time–temperature superposition principle (TTSP) enables direct quantitative comparison of simulation with experiment. Here, we follow-up and present results for the translational dynamics of the same material over a temperature range from the rubbery to the glassy state. Using TTSP, we obtain results for translational dynamics out to 10<sup>9</sup> s in TTSP reduced time – a macroscopic timescale. Further, we show that the mean squared displacement (MSD) trends of the network atoms can be collapsed onto a master curve at a reference temperature. The computational master curve is compared with the experimental master curve of the creep compliance for the same network using literature data. We find that the temporal features of the two data sets can be quantitatively compared providing an integrated view relating molecular level dynamics to the macroscopic thermophysical measurement. The time-shift factors needed for the superposition also show excellent agreement with experiment further establishing the veracity of the approach</a>.

scholarly journals Microstructure and Photothermal Conversion Performance of Ti/(Mo-TiAlN)/(Mo-TiAlON)/Al2O3 Selective Absorbing Film for Non-Vacuum High-Temperature Applications

2020 ◽  
Vol 11 (1) ◽  
pp. 124
Author(s):  
Haibin Geng ◽  
Hanzhe Ye ◽  
Xingliang Chen ◽  
Sibin Du
Keyword(s):  
Visible Light ◽  
Near Infrared ◽  
Substitutional Solid Solution ◽  
Experimental Conditions ◽  
Al Content ◽  
Spectrum Range ◽  
Light Interference ◽  
Transmission Electron ◽  
Conversion Performance ◽  
Columnar Grain

This paper aims to clarify the phase composition in each sub-layer of tandem absorber TiMoAlON film and verify its thermal stability. The deposited multilayer Ti/(Mo-TiAlN)/(Mo-TiAlON)/Al2O3 films include an infrared reflectance layer, light interference absorptive layers with different metal doping amounts, and an anti-reflectance layer. The layer thicknesses of Ti, Mo-TiAlN, Mo-TiAlON, and Al2O3 are 100, 300, 200, and 80 nm, respectively. Al content increases to 12 at.% and the ratio of N/O is nearly 0.1, which means nitride continuously changes to oxide. According to X-ray Diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) results, the diffraction peak that appears at 2θ = 40° demonstrates that Mo element aggregates in the substitutional solid solution (Ti,Al)(O,N) columnar grain. TiMoAlON films have low reflectivity in the spectrum range of 300–900 nm. When Al content is more than 10 at.%, absorptivity is almost in the spectrum range from visible to infrared, but absorptivity decreases in the ultraviolet spectrum range. When Al content is increased to 12 at.%, absorptivity α decreases by 0.05 in the experimental conditions. After baking in atmosphere at 500 °C for 8 h, the film has the highest absorptivity when doped with 2 at.% Mo. In the visible-light range, α = 0.97, and in the whole ultraviolet-visible-light near-infrared spectrum range, α = 0.94, and emissivity ε = 0.02 at room temperature and ε = 0.10 at 500 °C.

scholarly journals Mechanical Testing and Modeling of the Time–Temperature Superposition Response in Hybrid Fiber Reinforced Composites

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1178
Author(s):  
Aggelos Koutsomichalis ◽  
Thomas Kalampoukas ◽  
Dionysios E. Mouzakis
Keyword(s):  
Hybrid Composites ◽  
High Stress ◽  
Woven Fabrics ◽  
Mathematical Function ◽  
Ballistic Performance ◽  
Three Point Bending ◽  
Highly Nonlinear ◽  
Nonlinear Stress ◽  
Temperature Superposition ◽  
Time Temperature Superposition

The purpose of this study was to manufacture hybrid composites from fabrics with superior ballistic performance, and to analyze their viscoelastic and mechanical response. Therefore, composites in hybrid lay-up modes were manufactured from Vectran, Kevlar and aluminum fiber-woven fabrics through a vacuum assisted resin transfer molding. The specimens were consequently analyzed using static three-point bending, as well as by dynamic mechanical analysis (DMA). Apart from DMA, time–temperature superposition (TTS) analysis was performed by all available models. It was possible to study the intrinsic viscoelastic behavior of hybrid ballistic laminates, with TTS analysis gained from creep testing. A polynomic mathematical function was proposed to provide a high accuracy for TTS curves, when shifting out of the linearity regimes is required. The usual Williams–Landel–Ferry and Arrhenius models proved not useful in order to describe and model the shift factors of the acquired curves. In terms of static results, the highly nonlinear stress–strain curve of both composites was obvious, whereas the differential mechanism of failure in relation to stress absorption, at each stage of deformation, was studied. SEM fractography revealed that hybrid specimens with Kevlar plies are prone to tensile side failure, whereas the hybrid specimens with Vectran plies exhibited high performance on the tensile side of the specimens in three-point bending, leading to compressive failure owing to the high stress retained at higher strains after the maximum bending strength was reached.

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