Search results for "composition"
showing 10 items of 2675 documents
Litchi (Litchi chinensis Sonn.): a comprehensive review of phytochemistry, medicinal properties, and product development
2021
Since ancient times, litchi has been well recognized as a functional food for the management of various ailments. Many bioactives, including flavanoids, anthocyanins, phenolics, sesquiterpenes, triterpenes, and lignans, have been identified from litchi with a myriad of biological properties both in vitro and in vivo. In spite of the extensive research progress, systemic reviews regarding the bioactives of litchi are rather scarce. Therefore, it is crucial to comprehensively analyze the pharmacological activities and the structure-activity relationships of the abundant bioactives of litchi. Besides, more and more studies have focused on litchi preservation and development of its by-products,…
A Lagrange Multiplier Based Domain Decomposition Method for the Solution of a Wave Problem with Discontinuous Coefficients
2008
In this paper we consider the numerical solution of a linear wave equation with discontinuous coefficients. We divide the computational domain into two subdomains and use explicit time difference scheme along with piecewise linear finite element approximations on semimatching grids. We apply boundary supported Lagrange multiplier method to match the solution on the interface between subdomains. The resulting system of linear equations of the “saddle-point” type is solved efficiently by a conjugate gradient method.
A Unique Collection of Palaeolithic Painted Portable Art: Characterization of Red and Yellow Pigments from the Parpalló Cave (Spain).
2016
In this work we analyze the pigments used in the decoration of red and yellow motifs present in the portable art of the Parpallo Cave (Gandia, Spain), one of the most important Palaeolithic sites in the Spanish Mediterranean region. Energy dispersive X-ray fluorescence spectrometry (EDXRF) and spectrophotometry in the visible region (CIEL*a*b*color coordinates and spectral reflectance curves) were used to perform in situ fast analyses of the red and yellow motifs with portable equipment and to characterize their elemental composition and their colorimetric perception, respectively. According to the elemental composition, the intensity of the fluorescence iron signals in red and yellow motif…
EDXRF analysis of the Pentecost Triptych from the “São Pedro de Miragaia” church (Porto, Portugal)
2013
Abstract EDXRF spectrometry was used to determine the pigment composition of the Pentecost Triptych, a Flemish masterpiece located at the Church of Sao Pedro de Miragaia (Porto, Portugal). The triptych was restored at the beginning of the 20th century and presents a great number of zones with repaints and colour alterations that can be observed on the whole of their surface. The identification of the original pigments and restoration pigments was based on their characteristic colour and the correlation between the detected elements and the named “key elements” of ancient pigments (Ca, Fe, Cu, Hg, Pb,…) and modern pigments (Ti, Ba, Cr, Zn, Co, Cd,…). The analysis of the triptych has been car…
Archaeometrical Studies of Classic Mayan Mural Painting at Peten: La Blanca and Chilonche
2014
[EN] La Blanca and Chilonche are two of the many Mayan settlements located on the lower reaches of the Mopan river (Department of Petén, Guatemala). The archaeological work conducted by La Blanca Project (University of Valencia, Spain) over the last ten years has revealed the rich polychrome of the monumental architecture of these sites, where the remains of ancient mural paintings are of the highest quality. In order to ascertain the materials and techniques used by painters at each site throughout the Classic period, our research team has recently conducted an analytical study with a multi-technique approach based on the combination of several non destructive and micro-destructive instrum…
Estimating intrinsic image from successive images by solving underdetermined and overdetermined systems of the dichromatic model
2020
International audience; Estimating an intrinsic image from a sequence of successive images taken from an object at different angles of illumination can be used in various applications such as objects recognition, color classification, and the like; because, in so doing, it can provide more visual information. Meanwhile, according to the well-known dichromatic model, each image can be considered a linear combination of three components, including intrinsic image, shading factor, and specularity. In this study, at first, two simple independent constrained and parallelized quadratic programming steps were used for computing values of the shading factor and the specularity of each successive of…
Detection of events by means of plane wave decomposition analysis and cross-correlation technniques using a circular array of microphones
2013
[EN] This article deals with the study and analysis of room acoustics through a process of sound field decomposition sampled with microphones circular arrays. The spatial characteristics of the sound field inside a room can be meaningfully described by means of microphone array processing techniques. In this context, the set of impulse responses sampled by a microphone array can be seen as an image made of acoustic planewave footprints. Due to the circular geometry of the microphone array, these footprints have a cosine-like shape that can be fully described as a function of the direction of arrival (DOA) of the impinging plane wave.Plane-wave decomposition (PWD) technique using microphone …
Phytochemical Profile and Antioxidant Activity of the Aerial Part Extracts from Matthiola incana subsp. rupestris and subsp. pulchella (Brassicaceae)…
2021
As part of a project aimed at investigating the Matthiola taxa endemic to Sicily (Italy), this study focused on Matthiola incana, an edible species used in the traditional medicine of various countries. Herein, the characterization of phenolic and volatile compounds, the antioxidant capacity in vitro (1,1-diphenyl-2-picrylhydrazil (DPPH), reducing power and Fe2+ chelating activity assays) and the toxicity test (Artemia salina lethality bioassay) of the hydroalcoholic extracts from the aerial parts of M. incana subsp. rupestris from Mt. Pellegrino (Palermo) and Mt. Erice (Trapani), and of M. incana subsp. pulchella are reported. The results are compared with those previously shown for M. inc…
GC and GC-–MS Analysis of Volatile Compounds From Ballota nigra subsp. uncinata Collected in Aeolian Islands, Sicily (Southern Italy)
2020
In the present study, the chemical composition of the essential oils from aerial parts of Ballota nigra subsp. uncinata (Bég.) Patzak collected in Sicily was evaluated by gas chromatography (GC) and GC-mass spectrometry. The main components of the oil were ( E)-phytol (20.0%), α-pinene (9.0%), hexahydrofarnesyl acetone (5.7%), and α-selinene (5.1%). Cluster analysis of the essential oil compositions of all the taxa belonging to B. nigra s.l. group was performed.
Study of quantitative and qualitative variations in essential oils of Sicilian Rosmarinus officials L.
2015
In this study the chemical characterizations of 10 sicilian biotypes of Rosmarinus officinalis L. essential oils are reported. The main goal was to analyze the relationship between the essential oils yield and the geographical distribution of the species plants. The essential oils were analyzed by GC-FID and GC-MS. The statistical methods Hierarchical Cluster Analysis and Principal Component Analysis were used to cluster biotypes according to the chemical composition of the essential oils. The essential oil yield ranged from 0.8 - 2.3 (v/w). 82 compounds have been identified, these represent 96.7-99.9% of the essential oil. The compounds mostly represented in the essential oils were: 1.8- C…