Flocculation Gradient Technique in Terms of Kubelka—Munk Coefficients: Quantifying Black-Pigmented Dispersions

1995 ◽  
Vol 49 (12) ◽  
pp. 1756-1761 ◽  
Author(s):  
Marta Klanjšek Gunde ◽  
Zorica Crnjak Orel ◽  
Jasmina Kožar Logar ◽  
Boris Orel
Keyword(s):  
Layer Thickness ◽  
Diffuse Reflectance ◽  
Rate Of Change ◽  
Pigment Dispersion ◽  
Determination Method ◽  
Modified Method ◽  
Spectrally Selective ◽  
Gradient Technique ◽  
Painted Layer ◽  
High Absorption

The diffuse reflectance from a painted layer depends upon the layer thickness. The rate of change of diffuse reflectance when thickness increases is the flocculation gradient, which is valuable information about the degree of pigment dispersion in paint. The simple determination method is called the flocculation gradient technique and is suitable to quantify the pigment dispersions in low-absorptive and high-scattering paints. To make the method useful for black-pigmented paints as well, we modified it by applying the Kubelka–Munk theory. This makes it possible to solve the problem of the very narrow linearity region that appears in the diffuse reflectance vs. thickness curve because of high absorption. The modified method allows one to quantify the degree of dispersion in black thickness-sensitive spectrally selective paints, which are used as absorbers in solar collectors.

Sequestration of carbon in the humus layer of Swedish forests — direct measurements

2009 ◽  
Vol 39 (5) ◽  
pp. 962-975 ◽  
Author(s):  
Björn Berg ◽  
Maj-Britt Johansson ◽  
Åke Nilsson ◽  
Per Gundersen ◽  
Lennart Norell
Keyword(s):  
Layer Thickness ◽  
Forest Type ◽  
C Sequestration ◽  
Rate Of Change ◽  
Kriging Interpolation ◽  
Data Set ◽  
C Storage ◽  
Humus Layer ◽  
Sequestration Rate ◽  
Storage Rate

To determine sequestration rates of carbon dioxide (CO2) we calculated the carbon (C) storage rate in humus layers of Swedish forests with Podsolic soils, which account for 14.2 × 106 ha of the 22.7 × 106 ha of forested land in Sweden. Our data set covered 41 years of humus inventories and mean humus layer thickness in 82 513 plots. We analysed three forest types: (i) all combinations of tree species, (ii) forests dominated (>70%) by Norway spruce ( Picea abies (L.) Karst.), and (iii) forests dominated (>70%) by Scots pine ( Pinus sylvestris L.). To relate changes in humus layer thickness to land area we used the intersections in 25 km × 25 km grids and used kriging interpolation, permitting calculations for each forest type. For each intersection mean humus thickness for each year was calculated and regressed against time to obtain the rate of change. This rate, humus bulk density, and humus C concentration were used to calculate sequestration rates. The mean sequestration rate was 251 kg C·ha–1·year–1, which is higher than theoretical values. The sequestration rate was positively related to temperature sum, albeit including effects of forest management. The pine-dominated forest type had a mean rate of 283 kg C·ha–1·year–1, and the spruce-dominated had a mean rate of 239 kg C·ha–1·year–1. Under similar site conditions, pine sequestered more C than spruce (difference of 71 kg C·ha–1·year–1; p < 0.0001), showing the importance of this type of ecosystem for C sequestration.

Application of the Kubelka-Munk Theory to Thickness-Dependent Diffuse Reflectance of Black Paints in the Mid-IR

1995 ◽  
Vol 49 (5) ◽  
pp. 623-629 ◽  
Author(s):  
M. Klanjšek Gunde ◽  
J. Kožar Logar ◽  
Z. Crnjak Orel ◽  
B. Orel
Keyword(s):  
Penetration Depth ◽  
Layer Thickness ◽  
Spectral Dependence ◽  
Diffuse Reflectance ◽  
Boundary Surface ◽  
Applied Theory ◽  
Spectral Features ◽  
Scattering Medium ◽  
Scattering Coefficients ◽  
Munk Function

The Kubelka-Munk theory is applied to the thickness-dependent diffuse reflectance of black-painted samples in the mid-IR. The calculated absorption and scattering coefficients are wavenumber-dependent. The reflectance of the nonideal backing also shows spectral features, which is attributed to the reflections from the boundary surface between the scattering medium and the substrate. The spectral dependence of scattering penetration depth is caused by the scattering and absorption processes. At some wavenumbers, the diffuse reflectance is independent of layer thickness, because of particular values of the parameters of the applied theory. The application of the Kubelka-Munk function is discussed.

Diffuse reflectance spectroscopy's sensitivity to melanic layer thickness variations: an in vitro study on skin phantoms

2007 ◽  
Author(s):  
Marine Amouroux ◽  
Gilberto Diaz ◽  
Emilie Péry ◽  
Walter C. P. M. Blondel ◽  
François Guillemin
Keyword(s):  
Layer Thickness ◽  
Diffuse Reflectance ◽  
In Vitro Study ◽  
Vitro Study ◽  
Thickness Variations

Structure and Orientation of As Precipitates in LT-MBE Grown GaAs

1991 ◽  
Vol 49 ◽  
pp. 900-901 ◽  
Author(s):  
Alain Claverie ◽  
Zuzanna Liliental-Weber
Keyword(s):  
Transport Properties ◽  
Layer Thickness ◽  
Growth Temperature ◽  
Low Temperatures ◽  
Lattice Parameter ◽  
Crystalline Quality ◽  
Insulating Properties ◽  
Lt Gaas

GaAs layers grown by MBE at low temperatures (in the 200°C range, LT-GaAs) have been reported to have very interesting electronic and transport properties. Previous studies have shown that, before annealing, the crystalline quality of the layers is related to the growth temperature. Lowering the temperature or increasing the layer thickness generally results in some columnar polycrystalline growth. For the best “temperature-thickness” combinations, the layers may be very As rich (up to 1.25%) resulting in an up to 0.15% increase of the lattice parameter, consistent with the excess As. Only after annealing are the technologically important semi-insulating properties of these layers observed. When annealed in As atmosphere at about 600°C a decrease of the lattice parameter to the substrate value is observed. TEM studies show formation of precipitates which are supposed to be As related since the average As concentration remains almost unchanged upon annealing.

The stabilization of B.C.C. Cu in Cu/Nb nanolayered composites

1996 ◽  
Vol 54 ◽  
pp. 228-229
Author(s):  
H. Kung ◽  
A.J. Griffin ◽  
Y.C. Lu ◽  
K.E. Sickafus ◽  
T.E. Mitchell ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Layer Thickness ◽  
Volume Fraction ◽  
Ion Beam ◽  
High Strength ◽  
Cross Sectional ◽  
Metastable Structure ◽  
High Resolution Tem ◽  
Potential Improvement ◽  
Two Phases

Materials with compositionally modulated structures have gained much attention recently due to potential improvement in electrical, magnetic and mechanical properties. Specifically, Cu-Nb laminate systems have been extensively studied mainly due to the combination of high strength, and superior thermal and electrical conductivity that can be obtained and optimized for the different applications. The effect of layer thickness on the hardness, residual stress and electrical resistivity has been investigated. In general, increases in hardness and electrical resistivity have been observed with decreasing layer thickness. In addition, reduction in structural scale has caused the formation of a metastable structure which exhibits uniquely different properties. In this study, we report the formation of b.c.c. Cu in highly textured Cu/Nb nanolayers. A series of Cu/Nb nanolayered films, with alternating Cu and Nb layers, were prepared by dc magnetron sputtering onto Si {100} wafers. The nominal total thickness of each layered film was 1 μm. The layer thickness was varied between 1 nm and 500 nm with the volume fraction of the two phases kept constant at 50%. The deposition rates and film densities were determined through a combination of profilometry and ion beam analysis techniques. Cross-sectional transmission electron microscopy (XTEM) was used to examine the structure, phase and grain size distribution of the as-sputtered films. A JEOL 3000F high resolution TEM was used to characterize the microstructure.

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