10,507 research outputs found
Future dynamics in f(R) theories
The gravity theories provide an alternative way to explain the current
cosmic acceleration without invoking dark energy matter component. However, the
freedom in the choice of the functional forms of gives rise to the
problem of how to constrain and break the degeneracy among these gravity
theories on theoretical and/or observational grounds. In this paper to proceed
further with the investigation on the potentialities, difficulties and
limitations of gravity, we examine the question as to whether the future
dynamics can be used to break the degeneracy between gravity theories by
investigating the future dynamics of spatially homogeneous and isotropic dust
flat models in two gravity theories, namely the well known gravity and another by A. Aviles et al., whose motivation comes
from the cosmographic approach to gravity. To this end we perform a
detailed numerical study of the future dynamic of these flat model in these
theories taking into account the recent constraints on the cosmological
parameters made by the Planck team. We show that besides being powerful for
discriminating between gravity theories, the future dynamics technique
can also be used to determine the fate of the Universe in the framework of
these gravity theories. Moreover, there emerges from our numerical
analysis that if we do not invoke a dark energy component with
equation-of-state parameter one still has dust flat FLRW solution
with a big rip, if gravity deviates from general relativity via . We also show that FLRW dust solutions with do not
necessarily lead to singularity.Comment: 12 pages, 8 figures. V2: Generality and implications of the results
are emphasized, connection with the recent literature improved, typos
corrected, references adde
Structural and functional stabilization of glycomacropeptide via encapsulation within multiple emulsions
Bovine glycomacropeptide (GMP), derived from whey proteins, has been demonstrated to possess an interesting bioactivity that has attracted a lot of attention over the last few years. In particular, its ability to bind Vibrio cholerae and Escherichia coli enterotoxins, inhibit bacterial and viral adhesion, suppress gastric secretions, promote bifidobacterial growth and modulate immune system responses. Of these, protection against toxins, bacteria and viruses, and modulation of the immune system, are the most promising applications for this bioactive dairy macropeptide. The development of strategies that may allow its structural and functional stabilization via nanoencapsulation within multiple emulsions may increase its food and biopharmaceutical applicabilities. In this research effort, bovine GMP was (thermodynamically) stabilized via entrapment within water-in-oil-in-water (W/O/W) multiple emulsions aiming at mimicking the multifunctional design of biology, with several lipid matrices, and stabilizing layer compositions. Due to their compartimentalized internal structure, multiple emulsions are ideal for encapsulation since they can carry both polar and non-polar (bio)molecules. The composition of the stabilizing layer of the nanosystem was changed by using different poloxamers and proportions of lecithin. Physicochemical characterization of the optimized GMP-encasing nanovesicle formulations encompassed determination of Zeta potential and particle hydrodynamic size over storage time, surface morphology via CRYO-SEM, and microcalorimetric analysis via DSC
Quantized spin wave modes in magnetic tunnel junction nanopillars
We present an experimental and theoretical study of the magnetic field
dependence of the mode frequency of thermally excited spin waves in rectangular
shaped nanopillars of lateral sizes 60x100, 75x150, and 105x190 nm2, patterned
from MgO-based magnetic tunnel junctions. The spin wave frequencies were
measured using spectrally resolved electrical noise measurements. In all
spectra, several independent quantized spin wave modes have been observed and
could be identified as eigenexcitations of the free layer and of the synthetic
antiferromagnet of the junction. Using a theoretical approach based on the
diagonalization of the dynamical matrix of a system of three coupled, spatially
confined magnetic layers, we have modeled the spectra for the smallest pillar
and have extracted its material parameters. The magnetization and exchange
stiffness constant of the CoFeB free layer are thereby found to be
substantially reduced compared to the corresponding thin film values. Moreover,
we could infer that the pinning of the magnetization at the lateral boundaries
must be weak. Finally, the interlayer dipolar coupling between the free layer
and the synthetic antiferromagnet causes mode anticrossings with gap openings
up to 2 GHz. At low fields and in the larger pillars, there is clear evidence
for strong non-uniformities of the layer magnetizations. In particular, at zero
field the lowest mode is not the fundamental mode, but a mode most likely
localized near the layer edges.Comment: 16 pages, 4 figures, (re)submitted to PR
ANALYSIS OF NOx EMISSIONS AND SPECIFIC FUEL CONSUMPTION OF A DIESEL ENGINE OPERATING WITH DIESEL/BIODIESEL BLENDS
This study aims to examine experimentally the NOx emissions and the performance of a motor AGRALE M90, single cylinder, operating with diesel and biodiesel blends. The engine was linked to an electric generator, which provided 1500 W, 3000 W and 4500 W to an electrical system. The engine was tested with fuel blends containing different amounts of commercial diesel (B4) with palm biodiesel (B100). NOx emissions, as well as the specific fuel consumption of diesel, biodiesel and their mixtures were measured and analyzed. In this study, emissions of NOx have been prioritized over other pollutants by environmental issues and techniques. Air pollution by NOx causes serious respiratory problems. Furthermore, emissions of NOx enable a qualitative assessment of the combustion process. The results show that the commercial diesel has better performance in terms of energy efficiency and NOx emissions
Danos de lagartas de Elasmopalpus lignosellus no feijoeiro.
Elasmopalpus lignosellus (Zeller), conhecida como lagarta elasmo, é considerada uma das principais pragas de diversas culturas, causando danos elevados no feijoeiro em períodos de estiagem. Foi avaliado nesse trabalho o dano da lagarta de diferentes idades no feijoeiro no estágio de folhas primárias: 1) lagartas de um dia; 2) lagartas de três dias; 3) lagartas de cinco dias; 4) lagartas de sete dias; 5) lagartas de nove dias; 6) testemunha (sem inseto).Resumo
Danos de lagartas de Elasmopalpus lignosellus no feijoeiro.
Foi avaliado nesse trabalho o dano da lagarta de diferentes idades no feijoeiro no estágio de folhas primárias: 1) lagartas de um dia; 2) lagartas de três dias; 3) lagartas de cinco dias; 4) lagartas de sete dias; 5) lagartas de nove dias; 6) testemunha (sem inseto). Dez sementes da cv. Pérola foram semeadas em Latossolo vermelho escuro contido em vaso de plástico preto (12,5 cm altura, 16 cm diâmetro) em 24/08/2010
Sazonalidade das proteínas seminais de caprinos da raça Anglo-nubiana no Nordeste do Brasil.
Resumo: As proteínas seminais já são estudadas em várias espécies, entre elas a bovina, eqüina, e suína, mostrando influência sobre a qualidade e congelabilidade do sêmen, e, como conseqüência, na fertilidade dos machos. No entanto, estudos das proteínas seminais em caprinos ainda é incipiente. O objetivo desse trabalho foi identificar o perfil protéico do plasma seminal de caprinos da raça Anglo-nubiana nas épocas seca e chuvosa na região semi-árida do Nordeste do Brasil. [Seasonality of seminal proteins from Anglo-Nubian goats in Northeast of Brazil
Structural and functional stabilization of protein entities
XI Reunião Regional Nordeste da SBBq | 4th International Symposium in Biochemistry of Macromolecules and BiotechnologyStabilization of protein and protein-like molecules translates into preservation of both
structure and functionality during storage and/or targeting, and such stabilization is
mostly attained through establishment of a thermodynamic equilibrium with the
(micro)environment. The basic thermodynamic principles that govern protein structural
transitions and the interactions of the protein and/or peptide molecule with its
(micro)environment will, therefore, be tackled. Protein stabilization is based upon
dampening the molecular motions and, therefore, eliminating conformational transitions
while the molecule is still in the native 3D (folded) state. The 3D structure of a protein
molecule depends mostly on two types of interactions: intramolecular interactions
between aminoacid moieties and intermolecular interactions with solute and/or solvent
molecules present in its microenvironment. Stabilizing a biomolecule (aiming at
preserving its function) involves dampening its molecular motions, and this can be
achieved by reducing the chemical activity of the water present in its microenvironment,
thus stabilizing both its structure and functionality. Recently, the simultaneous
entrapment-stabilization of proteins and enzymes based on nanoencapsulation in a
nanoemulsion (W/O/W) matrix with an hydrophilic core has started to gain momentum.
Similarly to the stabilization mechanism of osmolytes, in nanoencapsulation the water
activity is altered thus affecting the molecular motions of the proteins. Highlights will also
be given to structural and functional stabilization of protein entities (viz. enzymes,
(macro)peptides, (recombinant) proteins, and bacteriophages) by chemical
methodologies. Modification of the biomolecules microenvironment via multipoint
covalent attachment onto a solid surface followed by hydrophylic polymer coimmobilization,
are some of the (latest) strategies that will be discussed.info:eu-repo/semantics/publishedVersio
Suscetibilidade de Elasmopalpus lignosellus ao milho transgênico (Bt).
Foram avaliados os híbridos de milho transgênico Herculex (Cry1F), Yieldgard Vtpro (Cry1A105,Cry2Ab2), Yieldgard (Cry1Ab) e Agrisure Viptera (Vip3A) na mortalidade, altura e massa seca da parte aérea e raiz de plantas de milho infestadas com lagartas de E. lignosellus.Resumo
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