443 research outputs found

    The plasticity of berry shrivelling in 'Shiraz': A vineyard survey

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    Berry water loss during late ripening is a cultivar dependent-trait and is accentuated in wine grape varieties such as 'Shiraz'. 'Shiraz' berry development was monitored in twelve vineyards over two seasons to characterise the extent of weight loss that can occur within a grape growing region. From veraison onwards, berry fresh mass was greatest in vineyards using excessive irrigation and least in vineyards using cautious irrigation strategies. In the first season, berry fresh mass increased, reached a maximum and subsequently declined. Conversely, in the second season, characterised by rain and high humidity, berry fresh mass increased, then stabilised without a consistent decline. In both seasons, berry sugar import rates were highest shortly after veraison but then declined gradually, terminating several weeks after the weight maximum. Notwithstanding that berries with large maximum weights tended to undergo greater rates of weight loss, these berries remained heavier at harvest compared to those berries that were smaller prior to the onset of weight loss. Canopy size, yield and crop load were not key determinants of berry weight loss rates. Berry anthocyanin and sugar accumulation were closely correlated during early ripening but anthocyanin degradation took place during the late weight loss phase

    Timing of N application and water constraints on N accumulation and juice amino N concentration in Chardonnay grapevines

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    The amount and timing of nitrogen (N) application to a vineyard is critical for must yeast assimilable nitrogen (YAN) concentrations. YAN concentrations and amino acid profiles are important for the fermentation process and wine composition. Commonly, N is applied at flowering to optimize leaf functioning or after harvest to enhance vine productivity the following season. In this study N was applied at various stages of berry development to determine allocation patterns between vine perennial and annual components and to assess when berry YAN concentrations can best be optimized. Five year old potted 'Chardonnay' vines received ammonium sulfate fertilizer at six different times from full bloom to two weeks before harvest and were also exposed to either full or half irrigation during that period. Reduced water supply resulted in a higher allocation of N to the perennial structures and less to the annual components of the vine. N allocation to the annual components of the vine was greatest when it was applied at full bloom, however allocation to the perennial components was greatest when it was applied after fruit-set to veraison. The timing of N supply had a substantial influence on YAN concentrations, and was highest when N was applied about two weeks after veraison. Low water supply also resulted in higher juice YAN concentrations. The perennial N reserves in the roots were highest under low water supply and when N was applied at veraison, while the allocation to the annual parts was lower under this irrigation regime. The study indicates that timing of N application and the application of water constraints during berry development can impact on N partitioning, while the total amount accumulated by the vine is not altered

    Mineral sinks within ripening grape berries (Vitis vinifera L.)

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    Trends in the accumulation of mineral elements into the grape berry components give information about vascular flow into the berry. Shiraz berries were dissected into receptacle, skin, pulp, brush and seeds and the accumulation of 10 mineral elements into these components was followed through development. The elements were separated into two categories according to their accumulation pattern into the berry. The first group of elements continued to accumulate throughout berry growth and ripening, and was comprised of  phloem-mobile potassium, phosphorus, sulphur, magnesium, boron, iron and copper. The second group of elements accumulated mostly prior to veraison, and included the xylem-mobile minerals calcium, manganese and zinc. These results indicate that the xylem contribution to berry growth diminished after veraison. Berry fresh weight, dry weight, as well as berry sugar content, were all highly correlated with berry potassium content. While the pulp and skin were the strongest sinks for potassium and boron, seeds were the strongest sinks for calcium, phosphorus, sulphur, manganese and zinc. With the exception of calcium and manganese, seeds ceased to accumulate most elements during late ripening. The berry receptacle and brush did not accumulate any of the elements to levels above those of the other berry components at any stage of development. Therefore, they did not act as sinks for xylem- or phloem-mobile elements as vascular flow to the pulp and skin slowed.

    Prevention of mist formation in amine based carbon capture : field testing using a Wet ElectroStatic Precipitator (WESP) and a Gas-Gas Heater (GGH)

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    This study presents the results of two field tests that aimed at evaluating two countermeasures (WESP and GGH) to avoid acid mist formation. A WESP is shown to be very efficient for the removal of nuclei from the flue gas (100 % efficient) and thus can prevent aerosol formation inside an amine based absorber. This is however only valid in the absence of SO2 in the flue gas entering the WESP. A decreasing WESP efficiency is noted in the presence of SO2 with increasing voltages as a result of newly formed aerosols inside the WESP. This implies that no or very low levels of SO2 should be present in the flue gas entering the WESP. Since most of the amine carbon capture installations have a pre-scrubber (usually using NaOH to remove residual SO2 in the flue gas leaving the power plant's Flue Gas Desulphurisation) in front of their amine absorber, the WESP must be installed behind this pre-scrubber and not in front of it. Having a Gas-Gas Heater (or any type of flue gas cooling such as a Low Temperature Heat Exchanger) installed upstream of the wet scrubbing may prevent homogenous nucleation and thus prevent the conversion of H2SO4 into sulfuric acid aerosols and consequently mist formation issues in the amine based carbon capture installation. Which option to choose amongst the two countermeasures presented in this study will depend on whether a new built installation is being considered or whether a carbon capture is planned as a retrofit into an existing installation. (C) 2017 The Authors. Published by Elsevier Ltd

    Prevention of Mist Formation in Amine Based Carbon Capture: Field Testing Using a Wet ElectroStatic Precipitator (WESP) and a Gas-Gas Heater (GGH)

    Get PDF
    This study presents the results of two field tests that aimed at evaluating two countermeasures (WESP and GGH) to avoid acid mist formation. A WESP is shown to be very efficient for the removal of nuclei from the flue gas (100 % efficient) and thus can prevent aerosol formation inside an amine based absorber. This is however only valid in the absence of SO2 in the flue gas entering the WESP. A decreasing WESP efficiency is noted in the presence of SO2 with increasing voltages as a result of newly formed aerosols inside the WESP. This implies that no or very low levels of SO2 should be present in the flue gas entering the WESP. Since most of the amine carbon capture installations have a pre-scrubber (usually using NaOH to remove residual SO2 in the flue gas leaving the power plant's Flue Gas Desulphurisation) in front of their amine absorber, the WESP must be installed behind this pre-scrubber and not in front of it. Having a Gas-Gas Heater (or any type of flue gas cooling such as a Low Temperature Heat Exchanger) installed upstream of the wet scrubbing may prevent homogenous nucleation and thus prevent the conversion of H2SO4 into sulfuric acid aerosols and consequently mist formation issues in the amine based carbon capture installation. Which option to choose amongst the two countermeasures presented in this study will depend on whether a new built installation is being considered or whether a carbon capture is planned as a retrofit into an existing installation. (C) 2017 The Authors. Published by Elsevier Ltd

    Effect of Gravity and Confinement on Phase Equilibria: A Density Matrix Renormalization Approach

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    The phase diagram of the 2D Ising model confined between two infinite walls and subject to opposing surface fields and to a bulk "gravitational" field is calculated by means of density matrix renormalization methods. In absence of gravity two phase coexistence is restricted to temperatures below the wetting temperature. We find that gravity restores the two phase coexistence up to the bulk critical temperature, in agreement with previous mean-field predictions. We calculate the exponents governing the finite size scaling in the temperature and in the gravitational field directions. The former is the exponent which describes the shift of the critical temperature in capillary condensation. The latter agrees, for large surface fields, with a scaling assumption of Van Leeuwen and Sengers. Magnetization profiles in the two phase and in the single phase region are calculated. The profiles in the single phase region, where an interface is present, agree well with magnetization profiles calculated from a simple solid-on-solid interface hamiltonian.Comment: 4 pages, RevTeX and 4 PostScript figures included. Final version as published. To appear in Phys. Rev. Let

    The center effect in liver transplantation in the Eurotransplant region : a retrospective database analysis

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    Apart from donor and recipient risk factors, the effect of center-related factors has significant impact on graft survival after liver transplantation (LT). To investigate this effect in Eurotransplant, a retrospective database analysis was performed, including all LT's in adult recipients (18years) in the Eurotransplant region from 1.1.2007 until 31.12.2013. Additionally, a survey was sent out to all transplant centers requesting information on surgeons' experience and exposure. In total, 10265 LT's were included (median follow-up 3.3years), performed in 39 transplant centers. Funnel plots showed significant differences in graft survival between the transplant centers. After correction for donor and recipient risk, with the Eurotransplant donor risk index (ET-DRI) and the simplified recipient risk index (sRRI) and random effects, these differences diminished. Mean historical volume (in the preceding 5years) was a significant (P<0.001), nonlinear marker for graft survival in the multivariate analysis. This study demonstrates that funnel plots can be used for benchmarking purposes in LT. Case-mix correction can be performed with the use of the ET-DRI and sRRI. The center effect encompasses the entire complex process of preoperative workup, operation to follow-up

    Gradient critical phenomena in the Ising quantum chain: surface behaviour

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    We consider the influence of a power-law deviation from the critical coupling such that the system is critical at its surface. We develop a scaling theory showing that such a perturbation introduces a new length scale which governs the scaling behaviour of the density profiles as well as the finite-size behaviour of the surface properties. Exact results are obtained for the Ising quantum chain when the perturbation varies linearly whereas the quadratic perturbation is mainly studied numerically. The scaling theory is well confirmed in both cases

    Solvable Kinetic Gaussian Model in External Field

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    In this paper, the single-spin transition dynamics is used to investigate the kinetic Gaussian model in a periodic external field. We first derive the fundamental dynamic equations, and then treat an isotropic d-dimensional hypercubic lattice Gaussian spin system with Fourier's transformation method. We obtain exactly the local magnetization and the equal-time pair correlation function. The critical characteristics of the dynamical, the complex susceptibility, and the dynamical response are discussed. The results show that the time evolution of the dynamical quantities and the dynamical responses of the system strongly depend on the frequency and the wave vector of the external field.Comment: 11 page

    Glauber Critical Dynamics: Exact Solution of the Kinetic Gaussian Model

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    In this paper, we have exactly solved Glauber critical dynamics of the Gaussian model on three dimensions. Of course, it is much easy to apply to low dimensional case. The key steps are that we generalize the spin change mechanism from Glauber's single-spin flipping to single-spin transition and give a normalized version of the transition probability . We have also investigated the dynamical critical exponent and found surprisingly that the dynamical critical exponent is highly universal which refer to that for one- two- and three-dimensions they have same value independent of spatial dimensionality in contrast to static (equilibrium) critical exponents.Comment: 9 page
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