2,767 research outputs found
Effect of wood aging on wine mineral composition and 87Sr/86Sr isotopic ratio
The evolution of mineral composition and wine strontium isotopic ratio 87Sr/86Sr (Sr IR) during wood aging were
investigated. A red wine was aged in stainless steel tanks with French oak staves (Quercus sessiliflora Salisb.), with three industrial
scale replicates. Sampling was carried out after 30, 60, and 90 days of aging, and the wines were evaluated in terms of general
analysis, phenolic composition, total polysaccharides, multielement composition, and Sr IR. Li, Be, Mg, Al, Sc, Ti, V, Mn, Co, Ni,
Cu, Zn, Ga, Ge, As, Rb, Sr, Y, Zr, Mo, Sb, Cs, Ba, Pr, Nd, Sm, Eu, Dy, Ho, Er, Yb, Lu, Tl, and Pb elements and 87Sr/86Sr were
determined by quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS) and Na, K, Ca, and Fe by flame atomic
absorption spectrometry (FAAS). Two-way ANOVA was applied to assess wood aging and time effect on Sr IR and mineral
composition. Wood aging resulted in significantly higher concentrations of Mg, V, Co, Ni, and Sr. At the end of the aging period,
wine exhibited statistically identical Sr IR compared to control. Study suggests that wood aging does not affect 87Sr/86Sr, not
precluding the use of this parameter for wine traceability purposesinfo:eu-repo/semantics/publishedVersio
Ranking factors affecting emissions of GHG from incubated agricultural soils
Agriculture significantly contributes to global greenhouse gas (GHG) missions and there is a need to develop effective mitigation strategies. The efficacy of methods to reduce GHG fluxes from agricultural soils can be affected by a range of interacting management and environmental factors. Uniquely, we used the Taguchi experimental design methodology to rank the relative importance of six factors known to affect the emission of GHG from soil: nitrate (NO3?) addition, carbon quality (labile and non-labile C), soil temperature, water-filled pore space (WFPS) and extent of soil compaction. Grassland soil was incubated in jars where selected factors, considered at two or three amounts within the experimental range, were combined in an orthogonal array to determine the importance and interactions between factors with a L16 design, comprising 16 experimental units. Within this L16 design, 216 combinations of the full factorial experimental design were represented. Headspace nitrous oxide (N2O), methane (CH4) and carbon dioxide (CO2) concentrations were measured and used to calculate fluxes. Results found for the relative influence of factors (WFPS and NO3? addition were the main factors affecting N2O fluxes, whilst glucose, NO3? and soil temperature were the main factors affecting CO2 and CH4 fluxes) were consistent with those already well documented. Interactions between factors were also studied and results showed that factors with Little individual influence became more influential in combination. The proposed methodology offers new possibilities for GHG researchers to study interactions between influential factors and address the optimized sets of conditions to reduce GHG emissions in agro-ecosystems, while reducing the number of experimental units required compared with conventional experimental procedures that adjust one variable at a time
Water buffalo production in the Brazilian Amazon Basin: a review
The Brazilian Amazon has witnessed, in the last decades, an increase in the water buffalo (Bubalus bubalis) inventory, with interesting productivity results. As the Brazilian Amazon contains the main water buffalo population in the Americas, the aim of this work is to review its most relevant production systems and some peculiarities about meat and milk production in this territory. The opening section describes the Amazon Basin, the most common water buffalo breeds, a brief history of the local livestock farming beginning in 1644. Also, it presents how water buffaloes gradually replaced bovine herds, especially where the latter had a lower productive performance. The use of extensive or more intensified models is pointed out and the ecosystems in which buffaloes are raised are detailed since native or cultivated pastures can be used in floodplains or drylands. Buffalo raising is favored in the Amazon due to the climate, soil, genetic variability of forages, animal adaptability, and physical space. Thus, it is clear that buffaloes have a high potential for meat and milk production and are an alternative in the use of altered areas of the Amazon; and, in the recent past, the low profitability of buffalo farming in traditional production systems in the Amazon was the reason which made this activity economically unattractive. Most recent technologies as outdoor confinements and silvopastoral systems are pointed out as more suitable regarding land-use policies, and buffalo farming for meat and milk production fits perfectly in this context, with productivity and beneficial socioeconomicinfo:eu-repo/semantics/acceptedVersio
Effects of site dilution on the magnetic properties of geometrically frustrated antiferromagnets
The effect of site dilution by non magnetic impurities on the susceptibility
of geometrically frustrated antiferromagnets (kagome and pyrochlore lattices)
is discussed in the framework of the Generalized Constant Coupling model, for
both classical and quantum Heisenberg spins. For the classical diluted
pyrochlore lattice, excellent agreement is found when compared with Monte Carlo
data. Results for the quantum case are also presented and discussed.Comment: 5 pages, 3 figure
Towards the deformation quantization of linearized gravity
We present a first attempt to apply the approach of deformation quantization
to linearized Einstein's equations. We use the analogy with Maxwell equations
to derive the field equations of linearized gravity from a modified Maxwell
Lagrangian which allows the construction of a Hamiltonian in the standard way.
The deformation quantization procedure for free fields is applied to this
Hamiltonian. As a result we obtain the complete set of quantum states and its
discrete spectrum.Comment: 13 pages, no figures **preliminary entry **
Magnetization reversal process and nonlinear magneto-impedance in Cu/NiFe and Nb/NiFe composite wires
The magnetization reversal of Cu/NiFe and Nb/NiFe composite wires carrying AC
current is studied. The frequency spectrum of a voltage induced in a pick-up
coil wound around the wire is analyzed. The frequency spectrum is shown to
consist of even harmonics within a wide range of AC current amplitudes and
longitudinal DC magnetic fields. The strong dependencies of the harmonic
amplitudes on the DC field are found. The results obtained may be of importance
for the design of weak magnetic field sensors.Comment: 8 pages, 4 figures, publishe
Desenvolvimento de um procedimento de mineralização de mosto para análise elementar por digestão por microondas
Analytical NoteThe present work describes the development and validation of a high pressure microwave-assisted mineralization procedure for the determination
of metals in grape must by spectrometric techniques. Metals of special oenological and food safety importance (Al, Co, Cu, Cd, Pb) were
used as model elements to achieve the optimum working conditions. The study was conducted by monitoring their concentration in experimental
samples by ETAAS. Different combinations of HNO3 and H2O2 were tested and an optimal volume of 1 mL of each reagent, added to 2 mL
of sample, was selected for further studies. In comparison with experimental conditions described in literature for the mineralization of grape
must and wine by HPMW, the proposed procedure requires very low reagent consumption. Time and temperature were regarded as factors in
the optimization study of microwave oven program, resulting in 72 minutes of extension including ventilation. The procedure trueness and
precision were evaluated using grape must and wine samples. For each element three different levels of addition were performed. The recovery
range was from 94% (Co) to 113% (Pb) in grape must and from 96% (Cu) to 128% (Al) in wine. Relative standard deviations ranged from 1%
(Cd) to 11% (Al) in grape must and from 2% (Cd, Pb) to 9% (Co) in wine (n = 10). The proposed procedure is suitable for grape must and wine
mineralization with a view to trace element analysis
Influência De Níveis De Potássio No Crescimento Radicular E Na Absorção De Nutrientes Em Cultivares De Arroz De Terras Altas
Potassium (K) is an essential nutrient for upland rice growth, but little information on the effects of K on root growth and nutrient uptake capacity of upland rice is found. Therefore, an experiment was conducted under greenhouse conditions to evaluate the influence of soil K levels on root growth and nutrient uptake of four upland rice cultivars. A completely randomized experimental design, in a 4x4 factorial scheme (4 levels of K: 20, 40, 80, and 160 mg dm-3; 4 cultivars: Caiapó, BRS-Primavera, IAC-202, and Maravilha) was used, with four replications. Based on regression equations, the highest values of root length density would be found with 136 mg dm-3 of K. The root diameter and dry matter, shoot dry matter and shoot K concentration increased linearly with the increasing K rates. The shoot K concentration of the upland rice cultivars did not differ. The increased level of K in the soil reduced the shoot Ca concentration of intermediate and modern cultivars, and the shoot Mg concentration of all cultivars. The potassium fertilization increased the plant growth, but the magnitude of this effect varied according to the cultivar. © 2017, Universidade Federal Rural do Semi-Arid. All Rights Reserved.301324
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