Orthogonal protecting groups in the synthesis of tryptophanyl-hexahydropyrroloindoles

The synthesis of various polycyclic systems containing a C3a-Ni bond between a hexahydropyrrolo[2,3-b]indole and an indole tryptophan is described here. A series of experiments were performed to determine the best combination of five orthogonal protecting groups and the best reaction conditions for formation of said bond, which is a common feature among many recently discovered marine natural products.

Assignment markets with the same core

[spa] En el contexto de los juegos de asignación bilaterales, estudiamos el conjunto de matrices asociadas a mercados de asignación con el mismo nucleo. Se proporcionan condiciones sobre las entradas de la matriz que aseguran que los juegos de asignación asociados tienen el mismo núcleo. Se prueba que este conjunto de matrices que dan lugar al mismo núcleo forman un semirretículo con un número finito de elementos minimales y un único máximo. Se da una caracterización de estos elementos minimales. También se proporciona una condición suficiente para obtener un retículo.

Assignment markets with the same core

[spa] En el contexto de los juegos de asignación bilaterales, estudiamos el conjunto de matrices asociadas a mercados de asignación con el mismo nucleo. Se proporcionan condiciones sobre las entradas de la matriz que aseguran que los juegos de asignación asociados tienen el mismo núcleo. Se prueba que este conjunto de matrices que dan lugar al mismo núcleo forman un semirretículo con un número finito de elementos minimales y un único máximo. Se da una caracterización de estos elementos minimales. También se proporciona una condición suficiente para obtener un retículo.

Investigating ferromagnetism and charge order in Bi1-xSrxMnO3(x<0.3)ceramic oxides.

The possible coexistence of ferromagnetism and charge/orbital order in Bi3/4Sr1/4MnO3 has been investigated. The manganite Bi0.75Sr0.25MnO3, with commensurate charge balance, undergoes an electronic transition at TCO~600 K that produces a longrange modulation with double periodicity along a and c axis, and unusual anisotropic evolution of the lattice parameters. The previously proposed ferromagnetic properties of this new ordered phase were studied by magnetometry and diffraction techniques. In zero field the magnetic structure is globally antiferromagnetic, ruling out the apparition of spontaneous ferromagnetism. However, the application of magnetic fields produces a continuous progressive canting of the moments, inducing a ferromagnetic phase even for relatively small fields (H<<1 T). Application of pulsed high fields produces a remarkable and reversible spin polarization (under 30 T, the ferromagnetic moment is ~3 ¿B/Mn, without any sign of charge order melting). The coexistence of ferromagnetism and charge order at low and very-high fields is a remarkable property of this system.

The connection between distortion risk measures and ordered weighted averaging operators

Distortion risk measures summarize the risk of a loss distribution by means of a single value. In fuzzy systems, the Ordered Weighted Averaging (OWA) and Weighted Ordered Weighted Averaging (WOWA) operators are used to aggregate a large number of fuzzy rules into a single value. We show that these concepts can be derived from the Choquet integral, and then the mathematical relationship between distortion risk measures and the OWA and WOWA operators for discrete and finite random variables is presented. This connection offers a new interpretation of distortion risk measures and, in particular, Value-at-Risk and Tail Value-at-Risk can be understood from an aggregation operator perspective. The theoretical results are illustrated in an example and the degree of orness concept is discussed.

The efficiency of indicator groups for the conservation of amphibians in the Brazilian Atlantic Forest

The adequate selection of indicator groups of biodiversity is an important aspect of the systematic conservation planning. However, these assessments differ in the spatial scale, in the methods used and in the groups considered to accomplish this task, which generally produces contradictory results. The quantification of the spatial congruence between species richness and complementarity among different taxonomic groups is a fundamental step to identify potential indicator groups. Using a constructive approach, the main purposes of this study were to evaluate the performance and efficiency of eight potential indicator groups representing amphibian diversity in the Brazilian Atlantic Forest. Data on the geographic range of amphibian species that occur in the Brazilian Atlantic Forest was overlapped to the full geographic extent of the biome, which was divided into a regular equal-area grid. Optimization routines based on the concept of complementarily were applied to verify the performance of each indicator group selected in relation to the representativeness of the amphibians in the Brazilian Atlantic Forest as a whole, which were solved by the algorithm"simulated annealing", through the use of the software MARXAN. Some indicator groups were substantially more effective than others in regards to the representation of the taxonomic groups assessed, which was confirmed by the high significance of data (F = 312.76; p < 0.01). Leiuperidae was considered as the best indicator group among the families analyzed, as it showed a good performance, representing 71% of amphibian species in the Brazilian Atlantic Forest (i.e. 290 species), which may be associated with the diffuse geographic distribution of its species. This study promotes understanding of how the diversity standards of amphibians can be informative for systematic conservation planning on a regional scale.

World Polarization in carbon emissions, potential conflict and groups: an updated revision

Typically, conflicts in world environmental negotiations are related, amongst other aspects, to the level of polarization of the countries in groups with conflicting interests. Given the predictable relationship between polarization and conflict, it would seem logical to evaluate the degree to which the distribution of countries – for example, in terms of their CO2 emissions per capita – would be structured through groups which in themselves are antagonistic, as well as their evolution over time. This paper takes the concept of polarization to explore this distribution for the period 1992-2010, looking at different analytic approaches related to the concept. Specifically, it makes a comparative evaluation of the results associated with endogenous multi-polarization measures (i.e. EGR and DER indices), exogenous measures (i.e. Z-K or multidimensional index) and strict bipolarization measures (i.e. Wolfson’s measure). Indeed, the interest lies not only in evaluating the global situation of polarization by comparing the different approaches and their temporal patterns, but also in examining the explanatory capacity of the different proxy groups used as a possible reference for designing global environmental policy from a group premise. JEL codes: D39; Q43; Q56. Key words: polarization; carbon emissions; conflict;

Versatile methodology to hydrate alkynes, in the presence of a wide variety of functional groups, with Mercury(II) p-Toluensulfonamidate, under catalytic, mild and neutral conditions

A method to generate carbonylic compounds from alkynes under mild and neutral conditions, with excellent functional group compatibility and high yields, is described. Hydration takes place under catalytic conditions by using from 0.1 to 0.2 equivalents of the easily available and inexpensive mercury(II) p-toluensulfonamidate in a hydroalcoholic solution. After use the catalyst is iner tized and/or recycled ...

Accounting for adsorption and desorption in Lattice Boltzmann simulations

We report a Lattice-Boltzmann scheme that accounts for adsorption and desorption in the calculation of mesoscale dynamical properties of tracers in media of arbitrary complexity. Lattice Boltzmann simulations made it possible to solve numerically the coupled Navier-Stokes equations of fluid dynamics and Nernst-Planck equations of electrokinetics in complex, heterogeneous media. With the moment propagation scheme, it became possible to extract the effective diffusion and dispersion coefficients of tracers, or solutes, of any charge, e.g., in porous media. Nevertheless, the dynamical properties of tracers depend on the tracer-surface affinity, which is not purely electrostatic and also includes a species-specific contribution. In order to capture this important feature, we introduce specific adsorption and desorption processes in a lattice Boltzmann scheme through a modified moment propagation algorithm, in which tracers may adsorb and desorb from surfaces through kinetic reaction rates. The method is validated on exact results for pure diffusion and diffusion-advection in Poiseuille flows in a simple geometry. We finally illustrate the importance of taking such processes into account in the time-dependent diffusion coefficient in a more complex porous medium.

Convergent Approaches for the Synthesis of the Anti-tumoral Peptide, Kahalalide F. Study of Orthogonal Protecting Groups

Kahalalide compounds are peptides that are isolated from a Hawaiian herbivorous marine species of mollusc, Elysia rufescens, and its diet, the green alga Bryopsis sp. Kahalalide F and its synthetic analogues are the most promising compounds of the Kahalalide family because they show anti-tumoral activity. Linear solid-phase syntheses of Kahalalide F have been reported. Here we describe several new improved synthetic routes based on convergent approaches with distinct orthogonal protection schemes for the preparation of Kahaladide analogues. These strategies allow a better control and characterization of the intermediates because more reactions are performed in solution. Five derivatives of Kahalalide F were synthesized using several convergent approaches.

Approximation to the theory of affinities to manage the problems of the groupping process

New economic and enterprise needs have increased the interest and utility of the methods of the grouping process based on the theory of uncertainty. A fuzzy grouping (clustering) process is a key phase of knowledge acquisition and reduction complexity regarding different groups of objects. Here, we considered some elements of the theory of affinities and uncertain pretopology that form a significant support tool for a fuzzy clustering process. A Galois lattice is introduced in order to provide a clearer vision of the results. We made an homogeneous grouping process of the economic regions of Russian Federation and Ukraine. The obtained results gave us a large panorama of a regional economic situation of two countries as well as the key guidelines for the decision-making. The mathematical method is very sensible to any changes the regional economy can have. We gave an alternative method of the grouping process under uncertainty.

Coexistence of Two Kinds of Fluorinated Hydrogenated Micelles as Building Blocks for the Design of Bimodal Mesoporous Silica with Two Ordered Mesopore Networks

A simple and effective route has been developed for the synthesis of bimodal (3.6 and 9.4 nm) mesoporous silica materials that have two ordered interconnected pore networks. Mesostructures have been prepared through the self assembly mechanism by using a mixture of polyoxyethylene fluoroalkyl ether and triblock copolymer as building block. The investigation of the RF8(EO)9/P123/water phase diagram evidences that in the considered surfactant range of concentrations, the system is micellar (L1). DLS measurements indicate that this micellar phase is composed of two types of micelles, the size of the first one at around 7.6 nm corresponds unambiguously to the pure fluorinated micelles. The second type of micelles at higher diameter consists of fluorinated micelles which have accommodated a weak fraction of P123 molecules. Thus, in this study the bimodal mesoporous silica are really templated by two kinds of micelles.

Essential factors for control of the equilibrium in the reversible rearrangement of M3N@Ih-C80 fulleropyrrolidines: Exohedral functional groups versus endohedral metal clusters

The effects of exohedral moieties and endohedral metal clusters on the isomerization of M3N@Ih-C80 products from the Prato reaction through [1,5]-sigmatropic rearrangement were systematically investigated by using three types of fulleropyrrolidine derivatives and four different endohedral metal clusters. As a result, all types of derivatives provided the same ratios of the isomers for a given trimetallic nitride template (TNT) as the thermodynamic products, thus indicating that the size of the endohedral metal clusters inside C80 was the single essential factor in determining the equilibrium between the [6,6]-isomer (kinetic product) and the [5,6]-isomer. In all the derivatives, the [6,6]- and [5,6]-Prato adducts with larger metal clusters, such as Y3N and Gd3N, were equally stable, which is in good agreement with DFT calculations. The reaction rate of the rearrangement was dependent on both the substituent of exohedral functional groups and the endohedral metal-cluster size. Further DFT calculations and 13C NMR spectroscopic studies were employed to rationalize the equilibrium in the rearrangement between the [6,6]- and [5,6]-fulleropyrrolidines

The adequacy of different robust statistical tests in comparing two independent groups

In the current study, we evaluated various robust statistical methods for comparing two independent groups. Two scenarios for simulation were generated: one of equality and another of population mean differences. In each of the scenarios, 33 experimental conditions were used as a function of sample size, standard deviation and asymmetry. For each condition, 5000 replications per group were generated. The results obtained by this study show an adequate type error I rate but not a high power for the confidence intervals. In general, for the two scenarios studied (mean population differences and not mean population differences) in the different conditions analysed, the Mann-Whitney U-test demonstrated strong performance, and a little worse the t-test of Yuen-Welch.