24 research outputs found
Suitability of the cyclic voltammetry measurements and DPPH\u2022 spectrophotometric assay to determine the antioxidant capacity of food-grade oenological tannins
Twenty commercially available oenological tannins (including hydrolysable and condensed) were assessed for their antiradical/reducing activity, comparing two analytical approaches: The 2,2-diphenyl-1-picrylhydrazyl (DPPH\u2022) radical scavenging spectrophotometric assay and the cyclic voltammetry (CV) electrochemical method. Electrochemical measurements were performed over a 12200 mV\u2013500 mV scan range, and integrated anodic currents to 500 mV were used to build a calibration graph with (+)-catechin as a reference standard (linear range: From 0.0078 to 1 mM, R2 = 0.9887). The CV results were compared with the DPPH\u2022 assay (expressed as % of radical scavenged in time), showing high correlation due to the similarity of the chemical mechanisms underlying both methods involving polyphenolic compounds as reductants. Improved correlation was observed by increasing the incubation time with DPPH\u2022 to 24 h (R2 = 0.925), demonstrating that the spectrophotometric method requires a long-term incubation to complete the scavenging reaction when high-molecular weight tannins are involved; this constraint has been overcome by using instant CV measurements. We concluded that the CV represents a valid alternative to the DPPH\u2022 colorimetric assay, taking advantage of fast analysis and control on the experimental conditions and, because of these properties, it can assist the quality control along the supply chain
A tetragonal-to-monoclinic phase transition in a ferroelectric perovskite: the structure of PbZr(0.52)Ti(0.48)O3
The perovskite-like ferroelectric system PbZr(1-x)Ti(x)O3 (PZT) has a nearly
vertical morphotropic phase boundary (MPB) around x=0.45-0.50. Recent
synchrotron x-ray powder diffraction measurements by Noheda et al. [Appl. Phys.
Lett. 74, 2059 (1999)] have revealed a new monoclinic phase between the
previously-established tetragonal and rhombohedral regions. In the present work
we describe a Rietveld analysis of the detailed structure of the tetragonal and
monoclinic PZT phases on a sample with x= 0.48 for which the lattice parameters
are respectively: at= 4.044 A, ct= 4.138 A, at 325 K, and am= 5.721 A, bm=
5.708 A, cm= 4.138 A, beta= 90.496 deg., at 20K. In the tetragonal phase the
shifts of the atoms along the polar [001] direction are similar to those in
PbTiO3 but the refinement indicates that there are, in addition, local
disordered shifts of the Pb atoms of ~0.2 A perpendicular to the polar axis..
The monoclinic structure can be viewed as a condensation along one of the
directions of the local displacements present in the tetragonal phase. It
equally well corresponds to a freezing-out of the local displacements along one
of the directions recently reported by Corker et al.[J. Phys. Condens.
Matter 10, 6251 (1998)] for rhombohedral PZT. The monoclinic structure
therefore provides a microscopic picture of the MPB region in which one of the
"locally" monoclinic phases in the "average" rhombohedral or tetragonal
structures freezes out, and thus represents a bridge between these two phases.Comment: REVTeX, 7 figures. Modifications after referee's suggestion: new
figure (figure 5), comments in 2nd para. (Sect.III) and in 2nd & 3rd para.
(Sect. IV-a), in the abstract: "...of ~0.2 A perpendicular to the polar
axis.
Superconductivity in Fullerides
Experimental studies of superconductivity properties of fullerides are
briefly reviewed. Theoretical calculations of the electron-phonon coupling, in
particular for the intramolecular phonons, are discussed extensively. The
calculations are compared with coupling constants deduced from a number of
different experimental techniques. It is discussed why the A_3 C_60 are not
Mott-Hubbard insulators, in spite of the large Coulomb interaction. Estimates
of the Coulomb pseudopotential , describing the effect of the Coulomb
repulsion on the superconductivity, as well as possible electronic mechanisms
for the superconductivity are reviewed. The calculation of various properties
within the Migdal-Eliashberg theory and attempts to go beyond this theory are
described.Comment: 33 pages, latex2e, revtex using rmp style, 15 figures, submitted to
Review of Modern Physics, more information at
http://radix2.mpi-stuttgart.mpg.de/fullerene/fullerene.htm
Intermediate structural state in Bi1−xPrxFeO3 ceramics at the rhombohedral–orthorhombic phase boundary
Crystal structure of the Bi1−xPrxFeO3 ceramics of the compositions corresponding to the threshold concentrations separating the polar rhombohedral (R3c) and anti-polar orthorhombic (Pbam) phases has been investigated with X-ray diffraction, transmission electron microscopy and differential scanning calorimetry measurements performed in a broad temperature range. The structural study specifies the peculiarities of the temperature-driven transition into the non-polar orthorhombic (Pnma) phase depending on the structural state of the compounds at room temperature. The crystal structure analysis reveals the revival of the anti-polar orthorhombic phase upon the temperature-induced transition, thus assuming that it can be considered as the bridge phase between the polar rhombohedral and the non-polar orthorhombic phases.publishe
Vitis vinifera facing climate change
The entire wine industry production could roughly be separated into two major parts which are grapevine cultivation and winemaking, whereas the influence of climate change is more directly related to processes in the vineyard and grape production. On the other hand, even though winemaking can be directly affected by climate change (i.e. higher energy consumption for cooling systems during harvest period) it is mostly indirectly influenced through the usage of grapes which are nowadays cultivated in hotter and drier climate in certain wine regions. Therefore, to closely understand the impact of climate change on wine industry it is required to determine links between the major berry compounds (sugars, organic acids, aromatic and phenolic compounds) and weather factors
Home Appliances as Home Controllers: Concepts and Set-Top Box Implementation
In this paper we present a novel softwarebased home control platform suitable as an extension to digital home appliances that are equipped with a CPU (settop boxes, home theatre systems, TV sets, gaming consoles, etc). By using an appliance they are already accustomed to, users become able to control lights, appliances and media playback in their homes. Intelligence and awareness are achieved with a support for execution of recipes – preprepared scripts that define timely actions and respond to triggers obtained from sensors. Software abstraction layer facilitates integration of any desired communication protocol. In our prototype, we supported Zigbee and DMX for light control, X10 for light/appliances control over power line, as well as Ethernet-based optical cameras as motion/presence sensors and UPnP/DLNA based equipment for distributed media playback
FPGA design and implementation of a wavelet-domain video denoising system
Abstract. Multiresolution video denoising is becoming an increasingly popular research topic over recent years. Although several wavelet based algorithms reportedly outperform classical single-resolution approaches, their concepts are often considered as prohibitive for real-time processing. Little research has been done so far towards hardware customization of wavelet domain video denoising. A number of recent works have addressed the implementation of critically sampled orthogonal wavelet transforms and the related image compression schemes in Field Programmable Gate Arrays (FPGA). However, the existing literature on FPGA implementations of overcomplete (non-decimated) wavelet transforms and on manipulations of the wavelet coefficients that are more complex than thresholding is very limited. In this paper we develop FPGA implementation of an advanced wavelet domain noise filtering algorithm, which uses a non-decimated wavelet transform and spatially adaptive Bayesian wavelet shrinkage. The standard composite television video stream is digitalized and used as source for real-time video sequences. The results demonstrate the effectiveness of the developed scheme for real time video processing.
Climatic shifts in high quality wine production areas, Emilia Romagna, Italy, 1961-2015
In the presented work, daily observations of minimum and maximum temperatures and precipitation-spatially interpolated in a high-resolution grid (5 x 5 km)-were used to detect climate shifts in the viticultural appellation areas of the Emilia-Romagna (ER) region, in the periods 1961-1990 and 1986-2015. The growing season (April to October) minimum, mean, and maximum temperatures were significantly increased in the second period compared to the first over the majority of the ER. Precipitation did not differ significantly, with the exception of certain small northeastern areas of the ER. The detected changes affected the ER viticultural environment in several ways: (1) an increase in the number of days with maximum temperature exceeding 30 degrees C, which can induce plant stress; (2) changes in starting and ending dates of the climatologically defined growing season, dates of the first fall frost and the last spring frost, and length of the frost-free period; (3) shifts of most vineyard areas from 'Region 2/Region 3' to 'Region 3/Region 4' (according to the Winkler Index); (4) shifts of the majority of the grape-producing zones from 'temperate/warm temperate' to 'warm temperate/warm' (according to the Huglin Index); (5) de creased availability of soil water, which is necessary for grapevine development
Application of different techniques on stone fruit (Prunus spp.) drying and assessment of physical, chemical and biological properties: Characterization of dried fruit properties
Drying of stone fruit with different techniques and characterization of physical, chemical and biological properties of convective dried, vacuum dried and lyophilised stone fruit, as well as analysing and structuring the data sets by principal component analysis (PCA) were obtained in this paper. Drying technique significantly influenced the shear force, hardness, springiness and cohesiveness of dried apricot NS4 (Novi Sad 4) samples (p <.05); the total phenolic, flavonoid and monomeric anthocyanin content of dried sour cherry Feketicka, sweet cherry Lapins, sweet cherry Sweet Heart and plum Toptase samples and also the antioxidant capacity of dried sour cherry Feketicka, plum Anna Spath and peach Lela samples. The most noticeable differentiations of the stone fruit groups of samples dried with convective and vacuum drying and lyophilisation were observed in raw and dried sour cherry Feketicka and Erdi Botermo samples. Practical applications: The results and conclusions obtained in this research have various application in food industry in many aspects. First, part of the fruit varieties investigated in this study were developed at the Faculty of Agriculture and their application in the fruit drying industry has been thoroughly investigated. In addition, application of different drying techniques on different stone fruit species were applied in this research. Finally, the possibilities of preservation the most important quality indicators of dried fruit was observed. The impact of obtained conclusions and results in the field of agricultural and food industry is significant, since they could be applied in the industrial processes