Influence of thermoplastic starch plasticized with biodiesel glycerol on thermal properties of pp blends

Plastics have been used in short-life products, which have presented harmful consequences for the nature, because of the low degradation rate reached by the most common polyolefins. This work evaluates the mechanical and thermal properties of pure iPP, plasticized starch (TPS) with biodiesel (TPS_Bio) or commercial (TPS_Com) glycerols, and their blends (iPP/TPS_Plas). The addition of TPS_Plas caused an increasing on the cristallinity of iPP, mainly for the compositions 90/10 and 80/20, probably due to morphological alterations such as crosslinking, that may have modified the molecular arrangement of the iPP in the presence of glycerol.     

Stereoselective synthesis of novel 4,5-epoxy-1,2-oxazin-6-ones and alpha,beta-epoxy-gamma-amino acids from beta-lithiated oxazolinyloxiranes and nitrones

[reaction: see text] A stereoselective synthesis of 9,10-epoxy-1,6-dioxa-4,7-diazaspiro[4,5]decanes has been developed on the basis of the addition of beta-lithiated oxazolinyloxiranes to nitrones. Conversion of these spirocyclic derivatives into 4,5-epoxy-1,2-oxazin-6-ones and successively into alpha,beta-epoxy-gamma-amino acids, alpha-hydroxy-gamma-amino acids, and gamma-butyrolactams is described.     

GKB-FP: an algorithm for large-scale discrete ill-posed problems

We describe an algorithm for large-scale discrete ill-posed problems, called GKB-FP, which combines the Golub-Kahan bidiagonalization algorithm with Tikhonov regularization in the generated Krylov subspace, with the regularization parameter for the projected problem being chosen by the fixed-point method by Bazán (Inverse Probl. 24(3), 2008). The fixed-point method selects as regularization parameter a fixed-point of the function ‖r _λ ‖₂/‖f _λ ‖₂, where f _λ is the regularized solution and r _λ is the corresponding residual. GKB-FP determines the sought fixed-point by computing a finite sequence of fixed-points of functions ||r_l^(k)||₂/||f_l^(k)||₂\|r_{\lambda}^{(k)}\|_{2}/\|f_{\lambda}^{(k)}\|_{2}, where f_l^(k)f_{\lambda}^{(k)} approximates f _λ in a k-dimensional Krylov subspace and r_l^(k)r_{\lambda}^{(k)} is the corresponding residual. Based on this and provided the sought fixed-point is reached, we prove that the regularized solutions f_l^(k)f_{\lambda}^{(k)} remain unchanged and therefore completely insensitive to the number of iterations. This and the performance of the method when applied to well-known test problems are illustrated numerically.     

Distribution of distances between topologies and its effect on detection of phylogenetic recombination

Inferences about the evolutionary history of biological sequence data are greatly influenced by the presence of recombination, that tends to disrupt the phylogenetic signal. Current recombination detection procedures focus on the phylogenetic disagreement of the data along the aligned sequences, but only recently the link between the quantification of this disagreement and the strength of the recombination was realised. We previously described a hierarchical Bayesian procedure based on the distance between topologies of neighbouring sites and a Poisson-like prior for these distances. Here, we confirm the improvement provided by this topology distance and its prior over existing methods that neglect this information by analysing datasets simulated under a complex evolutionary model. We also show how to obtain a mosaic structure representative of the posterior sample based on a newly developed centroid method.     

DEVELOPABLE SURFACE PATCHES BOUNDED BY NURBS CURVES

In this paper we construct developable surface patches which are bounded by two rational or NURBS curves, though the resulting patch is not a rational or NURBS surface in general. This is accomplished by reparameterizing one of the boundary curves. The reparameterization function is the solution of an algebraic equation. For the relevant case of cubic or cubic spline curves, this equation is quartic at most, quadratic if the curves are Bézier or splines and lie on parallel planes, and hence it may be solved either by standard analytical or numerical methods.     

Multiplicity of closed Reeb orbits on prequantization bundles

We consider upper bounds on the growth of L ^p norms of restrictions of eigenfunctions and spectral clusters to geodesic segments in a nonpositively curved manifold in the high frequency limit. This sharpens results of Chen and Sogge as well as Xi and Zhang, which showed that the crux of the problem is to establish bounds on the mixed partials of the distance function on the covering manifold restricted to geodesic segments. The innovation in this work is the development of a formula for the third variation of arc length on the covering manifold, which allows for a coordinate free expressions of these mixed partials.     

The multicriteria analysis for construction of benchmarkers to support the Clinical Engineering in the Healthcare Technology Management

In developing countries, approximately half of the healthcare equipments are not in full use and the main cause of this is the inadequate management of them. The Clinical Engineering might face this problem in the healthcare environment analyzing the equipment with a health technological process perspective to identify opportunities of improvements. Generally, the inadequate management is a result of lack of systemized and contextualized information about the health technological process. The effort to make an adequate management generates an increasing interest in the use of benchmarker. Currently, the benchmarkers used by the Clinical Engineering are not representative of a health technological process as a whole. Health technological process concept is stated in this article. The multicriteria analysis methodology MCDA (Multicriteria Decision Aid) is used to obtain benchmarkers and to identify opportunities of improvements, thus generating conditions for that the Clinical Engineering consolidates its relevant contribution for the healthcare.     

On the stability of Mañé critical hypersurfaces

We construct examples of Tonelli Hamiltonians on ${\mathbb{T}^n}$ (for any n ≥ 2) such that the hypersurfaces corresponding to the Mañé critical value are stable (i.e. geodesible). We also provide a criterion for instability in terms of closed orbits in free homotopy classes and we show that any stable energy level of a Tonelli Hamiltonian must contain a closed orbit.     

Approach combining on-line metal exchange and tangential-flow ultrafiltration for in-situ characterization of metal species in humic hydrocolloids

This paper deals with the development and optimization of an analytical procedure using ultrafiltration and a flow-injection system, and its application in in-situ experiments to characterize the lability and availability of metal species in humic-rich hydrocolloids. The on-line system consists of a tangential flow ultrafiltration device equipped with a 3-kDa filtration membrane. The concentration of free ions in the filtrate was determined by atomic-absorption spectrometry, assuming that metals not complexed by aquatic humic substances (AHS) were separated from the complexed species (M–AHS) retained by the membrane. For optimization, exchange experiments using Cu(II) solutions and AHS solutions doped with the metal ions Ni(II), Mn(II), Fe(III), Cd(II), and Zn(II) were carried out to characterize the stability of the metal–AHS complexes. The new procedure was then applied in-situ at a tributary of the Ribeira do Iguape river (Iguape, São Paulo State, Brazil) and evaluated using the ions Fe(III) and Mn(II), which are considered to be essential constituents of aquatic systems. From the exchange between metal–natural organic matter (M–NOM) and the Cu(II) ions it was concluded that Cu(II) concentrations >485 μg L^?1 were necessary to obtain maximum exchange of the complexes Mn–NOM and Fe–NOM, corresponding to 100% Mn and 8% Fe. Moreover, the new analytical procedure is simple and opens up new perspectives for understanding the complexation, transport, stability, and lability of metal species in humic-rich aquatic environments.     

Long-range solvent effects on the orbital interaction mechanism of water acidity enhancement in metal ion solutions: a comparative study of the electronic structure of aqueous Mg and Zn dications

We study the dissociation of water coordinated to a divalent metal ion center, M2+ = Mg2+, Zn2+ using density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations. First, the proton affinity of a coordinated OH- group is computed from gas-phase Mg2+(H2O)5(OH-), which yields a relative higher gas-phase acidity for a Zn2+-coordinated as compared to a Mg2+-coordinated water molecule, DeltapKa(gp) = 5.3. We explain this difference on the basis of a gain in stabilization energy of the Zn2+(H2O)5(OH-) system arising from direct orbital interaction between the coordinated OH- and the empty 4s state of the cation. Next, we compute the acidity of coordinated water molecules in solution using free-energy thermodynamic integration with constrained AIMD. This approach yields pKa Mg2+ = 11.2 and pKa Zn2+ = 8.4, which compare favorably to experimental data. Finally, we examine the factors responsible for the apparent decrease in the relative Zn2+-coordinated water acidity in going from the gas-phase (DeltapKa(gp) = 5.3) to the solvated (DeltapKa = 2.8) regime. We propose two simultaneously occurring solvation-induced processes affecting the relative stability of Zn2+(H2O)5(OH-), namely: (a) reduction of the Zn 4s character in solution states near the bottom of the conduction band; (b) hybridization between OH- orbitals and valence-band states of the solvent. Both effects contribute to hindering the OH- --> Zn2+ charge transfer, either by making it energetically unfavorable or by delocalizing the ligand charge density over several water molecules.