Search results for "Pigments"
showing 10 items of 135 documents
Ultrafast excitation dynamics of low energy pigments in reconstituted peripheral light-harvesting complexes of photosystem I
2000
AbstractUltrafast dynamics of a reconstituted Lhca4 subunit from the peripheral LHCI-730 antenna of photosystem I of higher plants were probed by femtosecond absorption spectroscopy at 77 K. Intramonomeric energy transfer from chlorophyll (Chl) b to Chl a and energy equilibration between Chl a molecules observed on the subpicosecond time scale are largely similar to subpicosecond energy equilibration processes within LHCII monomers. However, a 5 ps equilibration process in Lhca4 involves unique low energy Chls in LHCI absorbing at 705 nm. These pigments localize the excitation both in the Lhca4 subunit and in LHCI-730 heterodimers. An additional 30–50 ps equilibration process involving red …
Differences in the activity and distribution of peroxidase from three different portions of germinative Brassica oleracea seeds.
2002
Peroxidase (POD, EC 1.11.1.7) activity, cellular localization and isozyme patterns were investigated in the seed integument, cotyledon and embryo axis of Brassica oleracea cv. Cappuccio during pregermination and seedling growth. Seeds started to germinate after 24 h of imbibition. POD activity was localized in the pigmented layer of the integument and in procambial strands of the cotyledon and embryo axis in the first 24 h of imbibition. It was localized in the integumental cells of palisade, pigmented and aleurone layers and in epidermal, meristematic, procambial cells and xylem elements of the root and hypocotyl after 48 h of imbibition. POD activity increased during germination and early…
Indagine composizionale sulle pitture di due vasi di Centuripe
2019
Due vasi Centuripe a Palermo sono stati analizzati utilizzando XRF portatile complementare e FTIR a riflessione totale spettroscopie. Le analisi consentono di chiarire la tavolozza e la tecnica della decorazione (pittura a tempera con un legante organico), e mostrano la presenza di pigmenti sia antichi che moderni (a causa di qualche recente riverniciatura). Uno dei risultati più interessanti è stata l'identificazione di due fasi del solfato di calcio nello strato sottostante i dipinti: a causa delle condizioni che trasformano il gesso in bassanite, la presenza di il gesso o, in alternativa, la bassanite in ciascuna parte analizzata possono rappresentare un criterio per distinguere l'origin…
On-line database of voltammetric data of immobilized particles for identifying pigments and minerals in archaeometry, conservation and restoration (E…
2016
[EN] A web-based database of voltammograms is presented for characterizing artists' pigments and corrosion products of ceramic, stone and metal objects by means of the voltammetry of immobilized particles methodology. Description of the website and the database is provided. Voltammograms are, in most cases, accompanied by scanning electron microphotographs, X-ray spectra, infrared spectra acquired in attenuated total reflectance Fourier transform infrared spectroscopy mode (ATR-FTIR) and diffuse reflectance spectra in the UV-Vis-region. For illustrating the usefulness of the database two case studies involving identification of pigments and a case study describing deterioration of an archae…
Investigations on standard pigments with multispectral and XRF analysis
2008
Integrated methodologies for qualitative and quantitative characterization of historical pigments
2014
Chemometric Tools to Point Out Benchmarks and Chromophores in Pigments through Spectroscopic Data Analyses
2021
Spectral preprocessing data and chemometric tools are analytical methods widely applied in several scientific contexts i.e., in archaeometric applications. A systematic classification of natural powdered pigments of organic and inorganic nature through Principal Component Analysis with a multi-instruments spectroscopic study is presented here. The methodology allows the access to elementary and molecular unique benchmarks to guide and speed up the identification of an unknown pigment and its recipe. This study is conducted on a set of 48 powdered pigments and tested on a real-case sample from the wall painting in S. Maria Delle Palate di Tusa (Messina, Italy). Four spectroscopic techniques …
Antioxidant activities of prickly pear ( Opuntia ficus indica) fruits and its betalains: betanin and indicaxanthin.
2004
Phytochemicals and phytomedicines are now an expanding research fields. A great number of active agents occurring in plants and herbs have been discovered, which is fundamental to find a rationale for the health effects of these herbs, in many cases used for centuries as traditional remedies. The knowledge of the mechanisms and molecular basis of their action is the final objective to understand the mode of action of the discovered principles. Studies on the bioactivity of cactus pear are very recent and results obtained so far, while exciting, now generate new questions. In vivo studies on healthy humans showed a strong protection of the body antioxidant system, and a marked reduction of p…
LU FMOF optometrijas un redzes zinātnes nodaļas un Latvijas optometristu un optiķu asociācijas konferenču referātu tēzes
2020
Tēzes no LU 78.starptautiskās zinātniskās konferences Cilvēka fizioloģijas un uztveres sēdes un LU Optometrijas un redzes zinātnes nodaļas un LOOA kopīgās klīniski praktiskās konferences Rīgā, 2020.gada 14., 16. februārī
Makulas pigmenta optisko blīvumu ietekmējošie faktori skolas vecuma bērniem
2019
Bakalaura darbs ir uzrakstīts latviešu valodā uz 37 lapaspusēm un satur 14 attēlus, 6 tabulas un 71 atsauci uz literatūras avotiem. Darba mērķis bija noskaidrot makulas pigmenta optisko blīvumu skolas vecuma bērniem Mārupes pamatskolā un tā saistību ar ķermeņa masas indeksu un citiem faktoriem. Pētījumā piedalījās 253 bērni vecumā no 7 līdz 14 gadiem (vidējais vecums 9 gadi), kuriem tika noteikts makulas pigmenta optiskais blīvums ar Macular Pigment Screener iekārtu, kas balstās uz hetereohromatisko flikera fotometriju. Bakalaura darbā netika pierādīta statistiski nozīmīga saistība starp makulas pigmenta optisko blīvumu un ķermeņa masas indeksu, dzimumu un varavīksnenes krāsu.