Search results for "visual_art.visual_art_medium"
showing 10 items of 2982 documents
Gas chromatography/mass spectrometry characterization of historical varnishes of ancient Italian lutes and violin
2007
The organic constituents of historical vanishes from two ancient Italian lutes and a Stradivari violin, kept in the Musée de la musique in Paris, have been characterized using gas chromatography-mass spectrometry. Results have been compared with the chromatograms and mass spectra of recent as well as old naturally aged reference materials. The three historical varnishes analyzed have been shown to be oil varnishes, probably mixtures of linseed oil with resins. Identification of diterpenoids and triterpenoids compounds, and of the resins that may have been ingredients of the varnishes, are discussed in this paper.
Longer wavelengths of light improve the growth, intake and feed efficiency of individually reared juvenile pikeperchSander lucioperca(L.)
2009
We tested the effects of monochromatic light on the specific growth rate (SGR), feed intake and feed efficiency (FE) of juvenile pikeperch, Sander lucioperca (L.). Pikeperch were reared individually for 42 days in aquaria covered with blue, green, yellow or red gelatin filters or white paper (control; n=5). Linear regression analysis indicated a significant positive effect of longer wavelengths of light on the condition factor (CF), FE and SGR. The final weight, SGR and CF were significantly higher in fish reared under red than under white light, and FE was better under green, yellow and red light than under white light (Dunnett's post hoc test, P<0.05) while blue was comparable to white li…
Pigment patterns in mutants affecting the biosynthesis of pteridines and xanthommatin in Drosophila melanogaster.
1986
Eye-color mutants of Drosophila melanogaster have been analyzed for their pigment content and related metabolites. Xanthommatin and dihydroxanthommatin (pigments causing brown eye color) were measured after selective extraction in acidified butanol. Pteridines (pigments causing red eye color) were quantitated after separation of 28 spots by thin-layer chromatography, most of which are pteridines and a few of which are fluorescent metabolites from the xanthommatin pathway. Pigment patterns have been studied in 45 loci. The pteridine pathway ramifies into two double branches giving rise to isoxanthopterin, “drosopterins,” and biopterin as final products. The regulatory relationship among the …
CO2-Based Non-ionic Surfactants: Solvent-Free Synthesis of Poly(ethylene glycol)-block-Poly(propylene carbonate) Block Copolymers
2013
Copolymerization of carbon dioxide (CO2) and propylene oxide (PO) is employed to generate amphiphilic polycarbonate block copolymers with a hydrophilic poly(ethylene glycol) (PEG) block and a nonpolar poly(propylene carbonate) (PPC) block. A series of poly(propylene carbonate) (PPC) di- and triblock copolymers, PPC-b-PEG and PPC-b-PEG-b-PPC, respectively, with narrow molecular weight distributions (PDIs in the range of 1.05–1.12) and tailored molecular weights (1500–4500 g mol−1) is synthesized via an alternating CO2/propylene oxide copolymerization, using PEG or mPEG as an initiator. Critical micelle concentrations (CMCs) are determined, ranging from 3 to 30 mg L−1. Non-ionic poly(propylen…
Spectrophotometric evaluation of dental bleaching under orthodontic bracket in enamel and dentin
2013
Aware of the diffusion capacity of bleaching in the dental tissues, many orthodontists are subjecting their patients to dental bleaching during orthodontic treatment for esthetic purposes or to anticipate the exchange of esthetic restorations after the orthodontic treatment. For this purpose specific products have been developed in pre-loaded whitening trays designed to fit over and around brackets and wires, with clinical efficacy proven. Objective: The objective of this study was to evaluate, through spectrophotometric reflectance, the effectiveness of dental blea - ching under orthodontic bracket. Material and methods: Thirty-two bovine incisors crown blocks of 8 mm x 8 mm height lengths…
Rhyolitic dykes of Paros Island, Cyclades
2005
Abstract The discovery of rhyolitic dykes from the NE part of the island of Paros is described here for the first time. The dykes that can be mapped for a length of ca. 1.1 km are striking about 6° and 38° NE. The width reaches up to 11m maximum. The rhyolitic rocks are porphyric with a fine-grained matrix of mainly feldspar, quartz, some biotites and opaques. K-feldspar, biotite and plagioclase occur as phenocrysts, and mafic-intermediate enclaves are common. At the chilled margin in contact to the gneissic country rocks the dykes are vitric. There, the enclaves have been preserved from contact reaction with the melt and alteration effects and show primary igneous minerals such as clinopyr…
Positron Studies of Subsurface Zone in Titanium Created in Sliding Wear
2014
Positron annihilation studies of the subsurface zone constituted during dry sliding in pure titanium are reported. A new type of defect depth profile in this zone, which is not an exponential decay usually reported for other metals and alloys, is observed. Two layers in the subsurface zone are present in this metal. In the layer adjacent to the worn surface, the characteristic plateau of the mean positron lifetime that extends to a depth of 60–70 μm was observed. Small vacancy clusters and dislocations were recognized in this layer. At deeper zone, the mean positron lifetime decreased exponentially in the manner typical for the other metals. In this zone, vacancy clusters increase in size a…
Complex-forming properties of peat humic acids from a raised bog profiles
2013
Abstract Humic substances (HS) belong to the most powerful complex-forming agents, significantly affecting major and trace element speciation in natural environment. Several authors have focused on humic–metal interactions, using differing methods and comparing humic substances on different sources. However, the intrinsic differences among the HS of different origin and the impact of humification degree on the complex formation between humic substances and metals have not received the necessary attention until now. The aim of this study is to determine the Cu(II) complexing capacity and stability constants of Cu(II) complexes of humic acids (HA) isolated from two well-characterized raised b…
U-Pb monazite ages from the Pakistan Himalaya record pre-Himalayan Ordovician orogeny and Permian continental breakup
2018
The Greater Himalayan Sequence in India and Nepal records crustal thickening processes that took place during and following the onset of India-Asia collision (ca. 54–50 Ma). These resulted in late Eocene–early Miocene kyanite- and sillimanite-grade regional metamorphism, and Oligocene–Miocene crustal anatexis, which formed migmatites and leucogranites. We present new U-Pb monazite data for kyanite- and sillimanite-grade gneisses of the Neoproterozoic to Cambrian Tanawal Formation in the Pakistan Himalaya, which have metamorphic ages of 482.4 ± 7.9 Ma and 464.5 ± 4.0 Ma, respectively. These ages, together with along-strike equivalent rocks in the Lesser Himalaya of India and Nepal, help to d…
A view of the vegetation and economic exploitation of the forest in the Late Neolithic sites of Les Jovades and Niuet (Alicante, Spain)
1992
SummaryThe results of the charcoal analysis obtained in two open air sites of the Late Neolithic, although contrasting with what is known so far about their economy, as well as with the results of different palaeoamblental studies undertaken in other sites, mainly caves with long sequences, within the same area or in other near areas, form the main interest of this paper. We will begin presenting the data pertaining to both sites individually which, in the final part, will be assessed in order to reach a better understanding of the relationship between men and their natural environment during the Neolithic period.