5,642 research outputs found
Seasonal Patterns of Herbage Accumulation Dynamics in Marandu Palisadegrass Subjected to Intensities of Continuous Stocking Management
It is relatively well reported in the literature that pastures can have similar forage net accumulation when managed with contrasting structures. However, we hypothesized that the patterns of forage accumulation dynamics of pastures managed at different canopy heights is dependent on environmental conditions. The experimental treatments were four canopy heights (10, 20, 30, and 40 cm), allocated to experimental units according to a randomized complete block design with four replicates and evaluated throughout four contrasting environmental seasons (Summer, Autumn, Winter-Early Spring, and Late Spring). Under favourable growing conditions greater forage accumulation was observed in pastures maintained taller; on the contrary, under more stressful conditions, net forage accumulation rate reduced as canopy height increased. Such patterns of responses were related to compensations between tiller population density and tissue flows during summer and late spring and the reduced capacity of taller canopies to compensate lower population with greater growth rates during autumn and winter-early spring. Pastures subjected to intensities of continuous stocking management change their patterns of forage growth as they transitioned from favourable to more abiotic stressful conditions suggesting that warm-season perennial grasses demand seasonal adjustments in grazing heights in order to maximize herbage production
Adherend thickness effect on the tensile fracture toughness of a structural adhesive using an optical data acquisition method
Adhesive bonding is nowadays a serious candidate to replace methods such as fastening or riveting, because of attractive mechanical properties. As a result, adhesives are being increasingly used in industries such as the automotive, aerospace and construction. Thus, it is highly important to predict the strength of bonded joints to assess the feasibility of joining during the fabrication process of components (e.g. due to complex geometries) or for repairing purposes. This work studies the tensile behaviour of adhesive joints between aluminium adherends considering different values of adherend thickness (h) and the double-cantilever beam (DCB) test. The experimental work consists of the definition of the tensile fracture toughness (GIC) for the different joint configurations. A conventional fracture characterization method was used, together with a J-integral approach, that take into account the plasticity effects occurring in the adhesive layer. An optical measurement method is used for the evaluation of crack tip opening and adherends rotation at the crack tip during the test, supported by a Matlab® sub-routine for the automated extraction of these quantities. As output of this work, a comparative evaluation between bonded systems with different values of adherend thickness is carried out and complete fracture data is provided in tension for the subsequent strength prediction of joints with identical conditions
Hemispheric asymmetry in the sunspot cycle as a nonextensive phenomenon
The appearance of dark sunspots over the solar photosphere is not considered
to be symmetric between the northern and southern hemispheres. Among the
different conclusions obtained by several authors, we can point out that the
North-South asymmetry is a real and systematic phenomenon and is not due to
random variability. In the present work, we selected the sunspot area data of a
sample of 13 solar cycles divided by hemisphere extracted from the Marshall
Space Flight Centre (MSFC) database to investigate the behavior of probability
distributions using an out-of-equilibrium statistical model a.k.a non-extensive
statistical mechanics. Based on this statistical framework, we obtained that
the non-extensive entropic parameter has a semi-sinusoidal variation with a
period of 22 year (Hale cycle). Among the most important results, we can
highlight that the asymmetry index revealed the dominance of the
northern hemisphere against the southern one. Thus, we concluded that the
parameter can be considered an effective measure for diagnosing
long-term variations of the solar dynamo. Finally, our study opens a new
approach to investigating solar variability from the nonextensive perspective.Comment: 17 pages, 2 tables and 5 figures. Submitted to Solar Physic
KINEMATIC ANALYSIS OF VOLLEYBALL SPIKE
Volleyball nowadays is, after soccer, the most practiced sport in Brazil (Bojikian, 2004). However, studies related to the patterns used by the athletes during training are not in common use, especially those aiming to help the coach detect failures. Our goal was to compare the kinematic pattern of the volleyball spike performed by three female athletes of the Sport Club Pinheiros who played as outside hitters. The analysed variables were: ankle, knee and elbow angles during the last step and jump, and the maximum height attained during the jump
Rammed earth: feasibility of a global concept applied locally
Rammed earth is an ancient building technique that has been continuously reinvented in the dynamic movement of people all over the world, where it has been used to build from dwellings to enormous fortresses and city walls. In the particular case of Portugal, the inhabitants have been closely related to earth construction. From one region to another, rammed earth, adobe and wattle-and-daub buildings are frequently found. The rammed earth construction is mainly found in the southern part of Portugal and is almost absent from the north. However, the relatively low seismic hazard of the north of Portugal plus the sustainability of earth as a building material encourages the development of this technique in the region. The suitability of the typical granite residual soils from the Minho region for rammed earth construction was assessed by means of an experimental program, in which three representative soils were subjected to expeditious and laboratory tests that evaluated the characteristics of the soils and the performance of rammed earth built with them. The results showed that the granite residual soils tested fulfil most of the requirements needed for rammed earth construction, being the low compressive strength its main limitation. In this way, an innovative and sustainable stabilization technique based on alkaline activation of fly ash is proposed
Crystal Structures of 2-Phenyl-2H-1,2,3-Triazol-4-Carbaldehyde, an Active a-Glycosidase Inhibition Agent, and (1-Phenyl-1H-1,2,3-Triazol-4-yl)Methyl Benzoate and (2-(4-Fluorophenyl)-2H-1,2,3-Triazole-4-yl)Methanol, Two Moderately Active Compounds
The use of the NCS crystallographic service at Southampton and the valuable assistance of the staff there are gratefully acknowledged. JLW thanks FAPERJ, Brazil for support.Peer reviewedPublisher PD
Rammed earth construction with granitic residual soils: the case study of northern Portugal
Building in unstabilised rammed earth results in low environmental impact. However, northern
Portugal has not historical tradition with this technique, and thus the suitability of the local granitic residual soils
is unknown. This paper presents an experimental investigation, where this possibility is assessed. The results
showed that these soils are unsuitable, and that rammed earth construction is only feasible if these soils go
through a stabilising process. The alkaline activation of fly ash was investigated as an environmentally friendly
stabilisation technique, and it proved to be capable of improving the performance of rammed earth
Charged multifluids in general relativity
The exact 1+3 covariant dynamical fluid equations for a multi-component
plasma, together with Maxwell's equations are presented in such a way as to
make them suitable for a gauge-invariant analysis of linear density and
velocity perturbations of the Friedmann-Robertson-Walker model. In the case
where the matter is described by a two component plasma where thermal effects
are neglected, a mode representing high-frequency plasma oscillations is found
in addition to the standard growing and decaying gravitational instability
picture. Further applications of these equations are also discussed.Comment: 14 pages (example added), to appear in Class. Quantum Gra
Processing of byproducts to improve nisin production by Lactococcus lactis
In the last years, disposal from dairy industries have received a special attention due its polluting
power in the environment. For this reason, studies have obtained a positive support to develop different
alternatives to recycle milk whey components. One of them is its utilization as culture media, aiming to
produce biomolecules with noble applications. Nisin is an extracellular peptide, produced by
Lactococcus lactis, this peptide has been applied as a natural additive once it presents broad
antibacterial activity. Applications of this bacteriocin include dental care products, pharmaceutical
products such as stomach ulcers and colon infection treatment and potential birth control. In batch
cultures, L. lactis was performed in two different groups of assays. The first group milk whey was
prepared in distilled water in four different concentrations: 100 g/l (S100); 50 g/l (S50); 30 g/l (S30); 10 g/l
(S10). In the second group of assays, two supplements were added in milk whey with concentration 100
g/l (S100): (1) 5 g/l yeast extract (A1); (2) 5 g/l yeast extract and 10 ml (v/v) tomato extract. Nisin activity
was assayed through agar diffusion utilizing Lactobacillus sakei. The results show that the utilization of
powder milk whey with concentration of 100 g/l can be used as a culture medium with supplementation.
This media is favorable to develop L. lactis cells and nisin production, reaching an activity of about 4
logAU. Biological processing of milk byproduct can be considered as one of the profitable utilization
alternatives, generating high-value bioproducts and stimulates researches for its use.The authors wish to thank the Brazilian Committees for the Scientific Technology Research (CNPq, FAPESP, CAPES), for financial support and scholarship
Nisin biotechnological production : evaluation and perspectives in the development of new applications
Nisin is a commercially available bacteriocin of the lantibiotic group produced by Lactococcus lactis ATCC 11454.
The importance of nisin as an effective preservative is the fact that its spectrum of inhibitory activity includes
almost all Gram-positive, Gram-negative and spoilage bacteria. With several favorable characteristics, this
compound has been widely used as a natural food biopreservative. On the other hand, biotechnological production
of fuel ethanol from different raw materials (sucrose-containing feedstocks - mainly sugar cane, starchy materials
and lignocellulosic biomass) has led to the increase in the researches with trends for improving the bio-ethanol
production. During these processes of bio-ethanol production antibiotic agents are added to the pre-fermented
broth to prevent unwanted microbial growth. Thus, different questions have been made in relation to performance
of the application of the nisin as a natural antibiotic to the ethanol production, as well as their beneficial effects
about the yield and productivity in this process. However, the solution to this problematic depends firstly on how
the development and implementation of technologies based on nisin production will be undertaken. Perspectives
towards the development of modern procedures of nisin production are still needed. In this work the main proposal
that has been discussed is the applicability of a novel micro-reactor operated under oscillatory flow mixing
envisaged for parallel screening and/or development of industrial bioprocesses in the nisin production. For this
reason, initially the objective of this study was to investigate the milk whey, a byproduct from dairy industries, in
nisin production aiming to evaluate the growth conditions for L. lactis. In batch cultures, L. lactis was performed in
raw milk whey and the nisin activity was assayed through agar diffusion utilizing Lactobacillus sakei ATCC 15521.
The results showed that milk whey media is propitious to develop L. lactis cells and produce nisin, reaching activity
around 105 AU.mL-1. Biological processing of milk sub-products (milk whey) can be considered one of profitable
utilization alternatives, generating high-value bioproducts and contributing to decrease rivers disposal. The use of
these sub-products as substrate together with further studies related to application of batch or continuous
oscillatory flow reactor would take the more efficient nisin production and finally to a possibility of its evaluation
and use in bio-ethanol production.Fundação para a Ciência e a Tecnologia (FCT)FAPESP/BrasilCAPES/Brasi
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