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Green Pigments (green + pigment)
Selected AbstractsThe Origin of the Halogen Effect on the Phthalocyanine Green PigmentsCHEMISTRY - AN ASIAN JOURNAL, Issue 6 2010Uck Lee Dr. Abstract The structure and the electronic and optical properties of halogenated copper-phthalocyanine (n,,m,(Hal)-CuPc) molecules are investigated, according to the variation in the substituted halogen-atom species (Hal=Cl or Br) at the , and , positions of isoindole ring with different numbers (n and m=0, 4, 8, or 16). Our results show that the halogen effect mainly results from a structural deformation rather than caused by electronic effects. A nonplanar deformation of the phthalocyanine chromophore of the n,,m,(Hal)-CuPc molecule causes a significant change only in the HOMO and HOMO-1 levels, rather than in the LUMO levels, which leads to the appearance of a green color arising from the large red-shifts of the Soret and Q bands. The present result may serve as an important reference point for designing novel halogen-free green pigments, in accordance with the environmental regulations for the restriction of hazardous substances (RoHS) in electronic and electrical devices. [source] PHYSICO-CHEMICAL AND STORAGE CHARACTERISTICS OF GARLIC PASTEJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 1 2001JASIM AHMED A processed paste with a total solids and pH value of 33% and 4.1, respectively was prepared from fresh garlic by addition of 10% sodium chloride (w/w) and citric acid. Appearance of green pigment (in terms of the Hunter color -a* value) was noticed in the product during preparation. Paste was thermally processed at 70, 80 or 90C, respectively for 15 min. Greening of paste decreased with increase in temperature. Rheological data revealed that garlic paste behaved as a psuedo-plastic fluid with a flow behavior and consistency index of 0.14 and 279 Pa.sn, respectively. The paste was analyzed periodically for color and microbiological counts. The product was found to be shelf stable at 25C for a period of at least 6 months. The green coloration decreased significantly (p<0.05) during storage. [source] Raman microscopic investigation of paint samples from the Rosalila building, Copan, HondurasJOURNAL OF RAMAN SPECTROSCOPY, Issue 10 2006Rosemary A. Goodall Abstract Micro-Raman spectroscopy was applied to the study of multiple layered wall paints from the Rosalila temple, Copan, Honduras, which dates to the Middle Classic period (A.D. 520 to 655). Samples of red, green and grey paint and a thick white overcoating were analysed. The paint pigments have been identified as hematite, celadonite or green earth and a combined carbon/mica mixture. By combining Raman spectroscopy with micro-ATR infrared spectroscopy and environmental scanning electron microscopy (ESEM), a detailed study has been made of the materials and processes used to make the stucco and paints. The use of green earth as a green pigment on Maya buildings has not been reported before. The combination of carbon and muscovite mica to create a reflective paint is also a novel finding. Copyright © 2006 John Wiley & Sons, Ltd. [source] OCCURRENCES OF GREEN EARTH PIGMENT ON NORTHWEST COAST FIRST NATIONS PAINTED OBJECTS*ARCHAEOMETRY, Issue 3 2009I. N. M. WAINWRIGHT An analytical study of First Nations painted objects from the Northwest Coast showed that green earth (celadonite) was used as a green pigment by Tlingit, Haida and Tsimshian artists. Green earth appears to have been used less frequently by Heiltsuk and Kwakwaka'wakw artists and was not found on Coast Salish or Nuu-chah-nulth objects. Microscopical samples of green paint from 82 Northwest Coast objects, as well as several pigment sources and mineral specimens, were analysed using Fourier transform infrared spectroscopy or X-ray diffraction. Green earth was the most frequently identified green pigment, found in approximately 40% of the samples. [source] Physical and chemical cues influencing the oviposition behaviour of Aphidius erviENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2000Donatella Battaglia Abstract The oviposition behaviour of the aphid parasitoid Aphidius ervi Haliday is influenced by both chemical and physical cues. Oviposition attack responses were elicited by paint pigments sealed into the tip of a glass capillary tube. Parasitoids reacted to yellow pigments with repeated oviposition attack responses, but they did not react to green pigments. The spectrum of reflected light from the yellow pigments was very similar to that from the ,green' natural host Acyrthosiphon pisum (Harris), with a high proportion of the total radiation energy being emitted in the yellow-orange wavebands (580,660 nm). Pea aphid cornicle secretion also elicited oviposition attack responses, which were not exclusively induced by its pale yellow-green colour. In fact, the oviposition attack response to capillary tips coated with cornicle secretion remained evident under red light conditions, which, in contrast, nearly completely suppressed the response to yellow pigments. Chemical compounds from cornicle secretion do not appear to be involved in parasitoid orientation, even though they stimulate intense oviposition attack responses. Olfactometer experiments showed that the putative kairomone involved acts only at very short range or on contact. Host exuviae, which also elicited strong and persistent oviposition reactions from A. ervi females, appear to be a good alternative source of ovipositional kairomone(s). This work confirms the existence of an aphid cuticular kairomone. [source] Maya blue,green pigments found in Calakmul, Mexico: a study by Raman and UV-visible spectroscopyJOURNAL OF RAMAN SPECTROSCOPY, Issue 8 2008Renata Garcia Moreno Abstract After more than two decades of fieldwork in the Maya archaeological site of Calakmul, Mexico, numerous remnants of blue and green pigments have been reported on wall paintings, as well as on funerary paraphernalia, such as masks, miniatures and vases. The importance of these pigments is linked to the sacred values that Maya people associate with blue and green colours since pre-Columbian times. These hues symbolise water, and are therefore associated with fertility and regeneration. This paper aims to perform a survey of the blue and green pigments used in the Early Classic and Late Classic periods in Calakmul (300,850 A.D.), in order to have a better understanding of their chemical composition and origin. Analyses were performed on microsamples using Raman and UV-visible spectroscopies to evaluate the possibilities that these techniques can offer in future in situ researches on Mesoamerican archaeological materials and objects. With these analyses, we have documented a large blue,green chromatic palette, which includes the earliest Blue Maya and Green Maya known to date, as well as malachite, pseudomalachite and an unknown-up-to-now blue-green mineral pigment, veszelyite, used specifically for ritual objects. The results indicate a careful selection of imported products and the mastering of a complex ancient Maya pictorial tradition. Copyright © 2008 John Wiley & Sons, Ltd. [source] ,Green earths': vibrational and elemental characterization of glauconites, celadonites and historical pigmentsJOURNAL OF RAMAN SPECTROSCOPY, Issue 8 2008Francesca Ospitali Abstract ,Green earths' are employed since antiquity as pigments in the creation of artworks. The minerals responsible for the colour belong to four groups: (1) the clayey micas celadonite and glauconite, undoubtedly the most common; (2) smectites; (3) chlorites; (4) serpentines. Whereas there have been several studies on clayey materials, mineralogical analyses in the field of cultural heritage are mainly limited to the identification of the green earth without specific characterization of the mineralogical species. This work shows a preliminary characterization by the multi-techniques approach of some raw minerals (glauconite, celadonite and ferroceladonite). Vibrational analyses have been correlated with elemental analyses, thanks to the hyphenated instrumentation of scanning electron microscopy with EDS and Raman structural and chemical analyser (SEM-EDS-SCA) probes, which permitted collection of EDS and Raman spectra on the same microscopic area. Micro-Raman and Fourier transform infrared attenuated total reflectance (FTIR-ATR) spectroscopies were able to distinguish between celadonite and glauconite. The use of different lasers revealed resonance effects in the Raman spectra. In addition to pure minerals, archaeological samples and commercial green earths were also analysed, thereby enabling a more precise classification of the green pigments in heterogeneous samples such as wall paintings. Some commercially available green earths were found to contain organic dyes. Copyright © 2008 John Wiley & Sons, Ltd. [source] Identification of nineteenth century blue and green pigments by in situ x-ray fluorescence and micro-Raman spectroscopyJOURNAL OF RAMAN SPECTROSCOPY, Issue 8-9 2004F. Rosi Abstract A mural painting by the innovative Italian miniaturist Napoleone Verga (1833,1918) was studied by a model protocol that combines an in situ non-destructive technique with laboratory micro-destructive vibrational investigations. The experimental procedure allowed us to acquire detailed information not only on Verga's palette and painting technique but also on undocumented retouches, using a very restricted number of samples. Copyright © 2004 John Wiley & Sons, Ltd. [source] On-site Raman analysis of Iznik pottery glazes and pigmentsJOURNAL OF RAMAN SPECTROSCOPY, Issue 7 2004Philippe Colomban Abstract On-site Raman analyses were performed at the Musée National de Céramique, Sèvres, France, on rare Iznik (former Nicaea) pottery produced from ,1480 to ,1620. A comparison was made with a series of shards. The town of production of these potteries was highly disputed in the 1980s and many questions still remain. The potential of glaze on-site analyses as a classification/dating tool was evaluated. The structure of the silicate glaze does not change with the sample (index of polymerization ,0.5,0.8, indicating a lead silicate composition); characteristic SiO stretching mode doublet at ,985 and 1030,1050 cm,1. By contrast, the corresponding signature of most of the ,Kütahya' wares peaks at ,1070,1090 cm,1. The lowest index is measured for a brilliant overglazed red bole, according to a lower temperature of (post)firing. The different crystalline phases identified in the glaze are ,-quartz, haematite, spinel, cassiterite, uvarovite garnet and zircon. White colour arises from ,-quartz slip in most samples studied. Cassiterite (SnO2) opacifier is only present in some early blue-and-white ceramics (Master of the Knots and Baba Nakkas style, ,1510,1530) and we do not have other evidence of its intentional use as an opacifier. Intentional addition of tin oxide is likely for colour lightening in some red, blue and in clear green boles. At least two types of red glazes and two types of Cr-containing green pigments are evidenced. Copyright © 2004 John Wiley & Sons, Ltd. [source] The Origin of the Halogen Effect on the Phthalocyanine Green PigmentsCHEMISTRY - AN ASIAN JOURNAL, Issue 6 2010Uck Lee Dr. Abstract The structure and the electronic and optical properties of halogenated copper-phthalocyanine (n,,m,(Hal)-CuPc) molecules are investigated, according to the variation in the substituted halogen-atom species (Hal=Cl or Br) at the , and , positions of isoindole ring with different numbers (n and m=0, 4, 8, or 16). Our results show that the halogen effect mainly results from a structural deformation rather than caused by electronic effects. A nonplanar deformation of the phthalocyanine chromophore of the n,,m,(Hal)-CuPc molecule causes a significant change only in the HOMO and HOMO-1 levels, rather than in the LUMO levels, which leads to the appearance of a green color arising from the large red-shifts of the Soret and Q bands. The present result may serve as an important reference point for designing novel halogen-free green pigments, in accordance with the environmental regulations for the restriction of hazardous substances (RoHS) in electronic and electrical devices. [source] | ||||||||||