Color characteristics of Beijing's regional woody vegetation based on Natural Color System

Seasonality is a typical characteristic of Beijing's regional vegetation, and plant color is one of the most prominent visual factors of vegetation dynamic. In this research, we explored the composition and dynamic characteristics of plant color in Beijing's urban vegetation, involving the analysis of overall characteristics and respective features of leaf, flower, and fruit colors. Color data was collected from 177 woody plant species in Beijing Botanical Garden, spanning their annual life cycle, and identified with the colorimetry of the Natural Color System (NCS). Correlation and regression analyses were applied to reveal the temporal dynamic features of overall plant color richness. Cluster analysis was applied to categorize tree species based on typical colors of various plant organs. Color richness and color dispersion were introduced as two factors to measure color diversity of various tree species, applied in species evaluation by sorting and principal component analysis (PCA). Color dispersion of three‐dimensional NCS data was measured with a modified SD based on the calculation of mean spatial distance in the NCS space. Main results are as follows. The first part is plant color composition. The composition of all plant colors contains 862 NCS color species, 20 blackness species ranging from 3 to 90, 20 chromaticness species ranging from 0 to 90, 35 hue species ranging from G10Y‐B90G, and N. The second part is temporal dynamic of overall color richness. Leaf color richness and total color richness are significantly positively correlated with pentad (5‐day) sequence; flower color richness is significantly negatively correlated with pentad sequence; and fruit color richness first increases and then decreases over time. The third part is cluster analysis of tree species. Based on typical growing‐leaf color, various tree species were clustered into 6 categories; based on typical senescent‐leaf color, various tree species were clustered into 6 categories; based on typical flower color, various tree species were clustered into 15 categories; based on typical fruit color, various tree species were clustered into 7 categories. The fourth part is color diversity evaluation of various tree species with PCA. According to the PCA of flower‐leaf color diversity, the species with higher leaf color diversity and higher flower color diversity include Cotinus coggygria, Lagerstroemia indica, and Amygdalus triloba; the species with higher flower color diversity and lower leaf color diversity include Campsis radicans and Tamarix chinensis; the species with higher leaf color diversity and lower flower color diversity include Acer ginnala and Crataegus pinnatifida; the species with lower color diversity both for flower and leaf colors include Fontanesia fortune and Gleditsia sinensis. According to the PCA of leaf color diversity, the species with higher leaf color diversity in both leaf growth period and leaf senescence period include Diospyros kaki, Lagerstroemia indica and Paeonia suffruticosa; the species with higher leaf color diversity in leaf growth period and lower leaf color diversity in leaf senescence period include Amygdalus persica ‘Atropurpurea’ and Prunus virginiana ‘Canada Red’; the species with higher leaf color diversity in leaf senescent period and lower color diversity in leaf growth period include Quercus palustris, Armeniaca sibirica, and Metasequoia glyptostroboides; the species with lower leaf color diversity for the whole leaf development period include Gleditsia sinensis and Swida walteri.     

Interrelation of the Swiss Colour Atlas (SCA-2541) and the Munsell Color Order System

The CIE tristimulus values of measured Swiss Colour Atlas samples were converted to Munsell notations using a colour notation conversion program. A selected subset of SCA-2541 sample points was chosen: the samples on the fully populated regularly spaced hues 6, 12, 18, 24, 30, 36, 42, 48, 54, and 60. The resulting Munsell notations were plotted onto Munsell Value-Chroma and Hue-Chroma planes and analysed for regularity of spacing and hue distribution around the achromatic axis. An earlier article has detailed the interrelation between the Natural Color System (NCS) and the Munsell Color Order System using similarly constructed charts. Comparison is made with the sample spacing of the NCS and SCA-2541 points when mapped into Munsell colour space, to determine similarities and differences between these two geometrically similar systems; both are double cones forming equilateral triangular constant hue planes. © 1997 John Wiley & Sons, Inc. Col Res Appl, 22, 111–120, 1997     

Whiteness,chromaticness, and blackness symmetries for CIELAB,with a numerical example

Whiteness, chromaticness, and blackness are defined for CIELAB. These NCS‐like color attributes offer an alternative to lightness and chroma for describing color. Their hue‐preserving symmetries are derived for tristimulus color space. A numerical example provides what theory predicts are visually uniform sequences of colors with constant lightness, whiteness, chromaticness, or blackness. Numerical approximation is unnecessary. Such sets of symmetric colors in one hue are visually interesting, and useful for computer aided design. The appropriateness of such attributes for CIELAB is briefly discussed. © 2010 Wiley Periodicals, Inc. Col Res Appl, 2010     

A kinetic study of acetoxylation of benzyl chloride—a model of activated allylic chlorides in PVC—using a crown ether complex

Benzyl chloride has been used in a kinetic study of chlorine replacement by acetoxy groups to model the behaviour of allylic chlorine during the acetoxylation of poly(vinyl chloride). Chlorine substitution was carried out in tetrahydrofuran at 30°C using a potassium acetate-crown ether complex with methanol to ensure homogeneous solution. The process followed an S_N2 mechanism. The orders of reaction with respect to benzyl chloride and potassium acetate were close to one, and the second order velocity constant was 4.2 x 10^?5 litre mol^?1 s^?1 when the molar ratio of crown ether to potassium acetate was approximately unity. Higher ratios caused a slight increase in rate constant. Substitution was followed by NMR spectroscopy which also revealed a proton exchange between methanol and acetate anion with an equilibrium constant 9.4 x 10^?2. This observation has suggested an explanation for the effect of some free-radical inhibitors on the rate of acetoxylation of poly(vinyl chloride) by potassium acetate in the presence of crown ether.     

Effect of F/P and OH/P molar ratios and condensation viscosity on the structure of phenol‐formaldehyde resol resins for overlays—A statistical study

A two‐level full factorial experimental design with three variables, formaldehyde‐to‐phenol (F/P) molar ratio, hydroxyl‐to‐phenol (OH/P) molar ratio, and condensation viscosity was implemented to determine the effect of the variables on the structure of phenol‐formaldehyde resol resins for paper overlay impregnation. Ten resins were prepared with F/P molar ratios between 1.9 and 2.3, OH/P molar ratios between 0.09 and 0.13, and condensation viscosities between 60 and 180 mPa s. The effect of these three independent variables on the chemical structure was analyzed by ¹³C‐NMR spectroscopy, on the molecular weight distribution by gel permeation chromatography, and on the reactivity by differential scanning calorimetry. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2942–2948, 2004