576 research outputs found
A Review of Tannin Determination Methods Using Spectrophotometric Detection in Red Wines and Their Ability to Predict Astringency
Astringency is an important sensory attribute that influences red wine quality. The astringent sensation inside the mouth is caused by a group of molecules called tannins. These molecules can be quantified and analysed by several numbers of methods, such as the Bate Smith method, Adams Harbertson assay, and methylcellulose precipitation method. All these methods are colourimetric, however they differ on the principle on which they are based and, as well as on the tannin pool they are able to measure. In the literature, it is possible to find a wide range of concentrations of tannins for the main red wines varieties, which have been evaluated by the methods herein reviewed. For instance, higher tannin concentrations are obtained using the Bate Smith method (2.08-3.48 g/L tannin) compared with the Adams Harbertson assay (0.58-0.14 g/L tannin), which exhibit the lowest results. However, studies that directly compare results obtained with these methods are scarce. The aim of this work is to compare tannin concentrations in red wines and along with how sensory astringency correlates with tannin concentration measured by these three methods
Usability improvements of the Thermipig model for precision pig farming
Pig livestock farming systems encounter several economic and environmental
challenges, connected with meat price decrease, sanitary norms, emissions etc. To deal with these
issues, methods and models to assess the performance of a pig production system have been
developed. For instance, Thermipig model represents the pig fattening room and simulates
performances of pigs at the batch level, taking into account interactions between the individual
variability of pigs, farmer's practices, room characteristics and outdoor climate conditions. The
model requires some static basic inputs fulfilled in several spreadsheets (such as rooms, pigs, and
dietary characteristics) but also data files for voluminous variable inputs (such as outdoor
temperature or climate control box parameters) for further modelling and outcome producing.
This leads to challenges in data providing by the farmers and have to be improved. This paper
deals with the implementation of the separate modules of the developed data warehouse system
for usability improvements of the Thermipig model. The idea is to substitute input from the data
files with online data input and automated variable processing by the model using the python
script for connection to the remote data warehouse. The data warehouse system is extended with
âProperty Setsâ section dealing with all the operations that can be performed to a set of input
variables. This approach demonstrates the ability of the data warehouse to act as data supplier for
the remote model. As well the outcome of the model is also transferable back to the data
warehouse for evaluation. This work is done within the Era-Net SuSan PigSys project - Improving
pig system performance through a whole system approach
Superconducting pairing and density-wave instabilities in quasi-one-dimensional conductors
Using a renormalization group approach, we determine the phase diagram of an
extended quasi-one-dimensional electron gas model that includes interchain
hopping, nesting deviations and both intrachain and interchain repulsive
interactions. d-wave superconductivity, which dominates over the
spin-density-wave (SDW) phase at large nesting deviations, becomes unstable to
the benefit of a triplet -wave phase for a weak repulsive interchain
backscattering term , despite the persistence of dominant SDW
correlations in the normal state. Antiferromagnetism becomes unstable against
the formation of a charge-density-wave state when exceeds some
critical value. While these features persist when both Umklapp processes and
interchain forward scattering () are taken into account, the effect
of alone is found to frustrate nearest-neighbor interchain - and
-wave pairing and instead favor next-nearest-neighbor interchain singlet or
triplet pairing. We argue that the close proximity of SDW and
charge-density-wave phases, singlet d-wave and triplet -wave superconducting
phases in the theoretical phase diagram provides a possible explanation for
recent puzzling experimental findings in the Bechgaard salts, including the
coexistence of SDW and charge-density-wave phases and the possibility of a
triplet pairing in the superconducting phase.Comment: 19 pages, 13 figure
Field-induced spin density wave in (TMTSF)NO
Interlayer magnetoresistance of the Bechgaard salt (TMTSF)NO is
investigated up to 50 teslas under pressures of a few kilobars. This compound,
the Fermi surface of which is quasi two-dimensional at low temperature, is a
semi metal under pressure. Nevertheless, a field-induced spin density wave is
evidenced at 8.5 kbar above 20 T. This state is characterized by a
drastically different spectrum of the quantum oscillations compared to the low
pressure spin density wave state.Comment: to be published in Phys. Rev. B 71 (2005
Fertilité des sols: conclusions du rapport sur l'état des sols de France
Les sols constituent une ressource naturelle non renouvelable. Leurs usages et leur devenir reprĂ©sentent un enjeu collectif majeur, tant pour les activitĂ©s agricoles ou sylvicoles que pour la prĂ©servation de la qualitĂ© de notre environnement. AprĂšs dix ans de travaux, le Groupement dâIntĂ©rĂȘt Scientifique sur les sols, le Gis Sol, a dressĂ© le premier bilan scientifiquement quantifiĂ© de lâĂ©tat des sols de France mĂ©tropolitaine et dâOutre-mer dans un rapport sur lâĂ©tat des sols de France publiĂ© en 2011. Ce rapport relĂšve des points positifs mais Ă©galement un certain nombre de prĂ©occupations du point de vue de la fertilitĂ©. Les sols agricoles ne prĂ©sentent pas dâĂ©volution mesurable de leur aciditĂ©, ce quiindique une bonne gestion du pH Ă lâĂ©chelle nationale. Le rapport fait en revanche Ă©tat de teneurs en phosphore relativement faibles pour de nombreux sols, et Ă lâinverse de situations dâexcĂ©dents trĂšs prĂ©occupantes en raison de son impact sur la qualitĂ© des eaux et lâeutrophisation des milieux. Il pose ainsi la question de la durabilitĂ© Ă long terme du systĂšme agricole actuel et celle dâune meilleure valorisation des effluents dâĂ©levage. Dâassez nombreuses situations pourraient Ă©galement ĂȘtre susceptibles de provoquer des carences en oligo-Ă©lĂ©ments pour des cultures exigeantes. Enfin, une inquiĂ©tude majeure concerne la progression de lâartificialisation des sols, qui sâest accĂ©lĂ©rĂ©e durant la derniĂšre dĂ©cennie et occasionne des pertes importantes de sols agricoles.Soils are a non-renewable, natural resource. Their uses and their future represent, therefore, a collective issue for agricultural and forestry production, as well as for the preservation of our environment. After ten years of work, the âGroupement dâintĂ©rĂȘt scientifique sur les solsâ, the Gis Sol (Soils Scientific Interest Group) has presented the first appraisal of soil quality in mainland France and its overseas territories in a report on the state of the soils in France published in 2011. This appraisal shows evidence for positive points but also highlights some concerns regarding soil fertility. Agricultural soils do not show a measurable change in their acidity, thus indicating an efficient management of pH at a national level. On the other hand, the report shows relatively low phosphorus levels for numerous soils, and inversely situations of structural excess which remain very worrying due to its impact on water quality and on the eutrophication of the environments. It also raises the questionsof the long-term sustainability of current cultivation systems and of a better treatment of effluents from livestock farming. Numerous situations also seem to be incompatible, for certain oligo-elements, with demanding cultures. At last, a major concern is the development of soil sealing, which has accelerated over the last decade and is responsible for the loss of large areas of agricultural soils
Incidence of epigeal nest-building termites in Brachiaria pastures in the Cerrado
This study aimed to determine the number of termite epigeal nests and estimate the soil turning capacity of termites in cultivated pasture environments and in a native vegetation area. Surveys were conducted in four areas: three pasture areas and a Cerrado area, measuring 5 ha each. For each nest, the height, the perimeter and diameter at the base were measured. The volume of each mound was calculated. Turned soil was determined by randomly sampling 30 termite mounds in a pasture area for bulk density determinations. The mean number of termite mounds per ha was 408; the highest number of termite nests (672 per ha) was found in the 10-year-old pasture. In terms of termite mound density, there was no difference between the Cerrado, 3-year-old pasture, and 3-year-old intercropped pasture treatments. The total area occupied by termite nests ranged from 0.4 to 1.0%. The mean bulk density of the nest materials was 1.05 g cm(-3). The total nests volume ranged from 4 to 11 m(3) ha(-1). The total mass of the soil turned by the termites ranged from 3.4 to 13.4 ton. ha(-1)
Spin and orbital frustration in MnSc_2S_4 and FeSc_2S_4
Crystal structure, magnetic susceptibility, and specific heat were measured
in the normal cubic spinel compounds MnSc_2S_4 and FeSc_2S_4. Down to the
lowest temperatures, both compounds remain cubic and reveal strong magnetic
frustration. Specifically the Fe compound is characterized by a Curie-Weiss
temperature \Theta_{CW}= -45 K and does not show any indications of order down
to 50 mK. In addition, the Jahn-Teller ion Fe^{2+} is orbitally frustrated.
Hence, FeSc_2S_4 belongs to the rare class of spin-orbital liquids. MnSc_2S_4
is a spin liquid for temperatures T > T_N \approx 2 K.Comment: 4 pages, to be published in Physical Review Letter
Astringency sub-qualities of red wines and the influence of wineâsaliva aggregates
Astringency is a sensory attribute, related to the quality and mouthfeel of red wines. However, the origin of astringency sub-qualities, such as the typical drying astringency found in immature grapes, is still unknown. Astringency of red wines with similar tannin content but different astringency sub-qualities, from different harvest dates, is studied. Astringency was characterised in terms of friction coefficient, polyphenol content, sensory analysis and tannin/salivaryâproteins aggregates characterisation. A different evolution during ripening was found for both Cabernet Sauvignon and CarmĂ©nĂšre, and tanninâprotein aggregates showed differences in size, shape and surface. The velvety sub-quality appears to be related to aggregates with low precipitation, and with specific surface characteristics as roundness and Feret diameter. Results from this work propose an effect of aggregates on sensory perception and opens the possibility to explore their effect on oral lubrication
Competing types of quantum oscillations in the 2D organic conductor (BEDT-TTF)8Hg4Cl12(C6H5Cl)2
Interlayer magnetoconductance of the quasi-two dimensional organic metal
(BEDT-TTF)8Hg4Cl12(C6H5Cl)2 has been investigated in pulsed magnetic fields
extending up to 36 T and in the temperature range from 1.6 to 15 K. A complex
oscillatory spectrum, built on linear combinations of three basic frequencies
only is observed. These basic frequencies arise from the compensated closed
hole and electron orbits and from the two orbits located in between. The field
and temperature dependencies of the amplitude of the various oscillation series
are studied within the framework of the coupled orbits model of Falicov and
Stachowiak. This analysis reveals that these series result from the
contribution of either conventional Shubnikov-de Haas effect (SdH) or quantum
interference (QI), both of them being induced by magnetic breakthrough.
Nevertheless, discrepancies between experimental and calculated parameters
indicate that these phenomena alone cannot account for all of the data. Due to
its low effective mass, one of the QI oscillation series - which corresponds to
the whole first Brillouin zone area - is clearly observed up to 13 K.Comment: 8 pages, 8 figures. To be published in Phys. Rev.
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