Changeover during in situ compositional modulation of hexacyanoferrate (Prussian Blue) material

This paper describes the importance of (H2O)(6) clusters in controlling the properties of hexacyanoferrate (Prussian Blue) materials. A careful in situ study of compositional changes by using electrogravimetric techniques (in ac and dc modes) in hexacyanoferrates containing K+ alkali metals reveals the existence of a changeover in the properties of these films in a narrow potential range. Control of the compositional variation of the changeover is dependent on the K+ stoichiometric number in the compound structure. However, a specific K+ occupation in the compound structure activates the occupation of the (H2O)(6) cluster by H3O+ and/or H+, causing the changeover in the properties of hexacyanoferrate film. Thus, the information thus obtained is very useful for understanding the mechanisms involved in the electrochemical reversible switch between ferrimagnetism/paramagnetism, semiconductor/metal and electroluminescence/nonelectroluminescence properties of molecular cyanide materials.

ANOTHER QUADRATURE RULE OF HIGHEST ALGEBRAIC DEGREE OF PRECISION

We consider certain quadrature rules of highest algebraic degree of precision that involve strong Stieltjes distributions (i.e., strong distributions on the positive real axis). The behavior of the parameters of these quadrature rules, when the distributions are strong c-inversive Stieltjes distributions, is given. A quadrature rule whose parameters have explicit expressions for their determination is presented. An application of this quadrature rule for the evaluation of a certain type of integrals is also given.

Optical transition probabilities and compositional dependence of Judd-Ofelt parameters of Er3+ ions in fluoroindate glass

Fluoroindate glasses containing 1, 2, 3, and 4 mol% ErF3 were prepared in a dry box under an argon atmosphere. Absorption spectra of these glasses at room temperature were obtained. The Judd-Ofelt parameters Ωλ (λ = 2, 4, 6) for f-f transitions of Er3+ ions as well as transition probabilities, branching ratios, radiative lifetimes, and peak cross-sections for stimulated emission of each band were determined. The concentration effect on the intensities is analyzed. The optical properties of the fluoroindate glasses doped with Er3+ ions are compared with those of other glasses described in the literature. © 1995.

Number of larval instars of the ant Pachycondyla (=Neoponera) villosa (Formicidae: Ponerinae) determined by the rule of Dyar

In this work we present the number of larval instars in the Ponerinae ant Pachycondyla (=Neoponera) villosa. The analysis of maximal head capsule width measurement of 147 larvae was made. Four larval instars were measured: 1st instar the cephalic capsule varied from 0.18mm to 0.22mm; 2nd instar from 0.23mm to 0.27mm; 3rd instar from 0.30mm to 0.33mm and the 4th instar varied from 0.35mm to 0.38mm. The mean growth rate was 1.2375 according to the rule of Dyar. We also reviewed the number of larval instars for 35 ant species.

Pb-210 and compositional data of sediments from Rondonian lakes, Madeira River basin, Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Compositional analysis for an unbiased measure of soil aggregation

Soil aggregation is an index of soil structure measured by mean weight diameter (MWD) or scaling factors often interpreted as fragmentation fractal dimensions (D-f). However, the MWD provides a biased estimate of soil aggregation due to spurious correlations among aggregate-size fractions and scale-dependency. The scale-invariant D-f is based on weak assumptions to allow particle counts and sensitive to the selection of the fractal domain, and may frequently exceed a value of 3, implying that D-f is a biased estimate of aggregation. Aggregation indices based on mass may be computed without bias using compositional analysis techniques. Our objective was to elaborate compositional indices of soil aggregation and to compare them to MWD and D-f using a published dataset describing the effect of 7 cropping systems on aggregation. Six aggregate-size fractions were arranged into a sequence of D-1 balances of building blocks that portray the process of soil aggregation. Isometric log-ratios (ilrs) are scale-invariant and orthogonal log contrasts or balances that possess the Euclidean geometry necessary to compute a distance between any two aggregation states, known as the Aitchison distance (A(x,y)). Close correlations (r>0.98) were observed between MWD, D-f, and the ilr when contrasting large and small aggregate sizes. Several unbiased embedded ilrs can characterize the heterogeneous nature of soil aggregates and be related to soil properties or functions. Soil bulk density and penetrater resistance were closely related to A(x,y) with reference to bare fallow. The A(x,y) is easy to implement as unbiased index of soil aggregation using standard sieving methods and may allow comparisons between studies. (C) 2012 Elsevier B.V. All rights reserved.

Optimum design of experiments for statistical inference

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Is The amphibian tree of life really fatally flawed?

Wiens (2007, Q. Rev. Biol. 82, 55-56) recently published a severe critique of Frost et al.'s (2006, Bull. Am. Mus. Nat. Hist. 297, 1-370) monographic study of amphibian systematics, concluding that it is a disaster and recommending that readers simply ignore this study. Beyond the hyperbole, Wiens raised four general objections that he regarded as fatal flaws: (1) the sampling design was insufficient for the generic changes made and taxonomic changes were made without including all type species; (2) the nuclear gene most commonly used in amphibian phylogenetics, RAG-1, was not included, nor were the morphological characters that had justified the older taxonomy; (3) the analytical method employed is questionable because equally weighted parsimony assumes that all characters are evolving at equal rates; and (4) the results were at times clearly erroneous, as evidenced by the inferred non-monophyly of marsupial frogs. In this paper we respond to these criticisms. In brief: (1) the study of Frost et al. did not exist in a vacuum and we discussed our evidence and evidence previously obtained by others that documented the non-monophyletic taxa that we corrected. Beyond that, we agree that all type species should ideally be included, but inclusion of all potentially relevant type species is not feasible in a study of the magnitude of Frost et al. and we contend that this should not prevent progress in the formulation of phylogenetic hypotheses or their application outside of systematics. (2) Rhodopsin, a gene included by Frost et al. is the nuclear gene that is most commonly used in amphibian systematics, not RAG-1. Regardless, ignoring a study because of the absence of a single locus strikes us as unsound practice. With respect to previously hypothesized morphological synapomorphies, Frost et al. provided a lengthy review of the published evidence for all groups, and this was used to inform taxonomic decisions. We noted that confirming and reconciling all morphological transformation series published among previous studies needed to be done, and we included evidence from the only published data set at that time to explicitly code morphological characters (including a number of traditionally applied synapomorphies from adult morphology) across the bulk of the diversity of amphibians (Haas, 2003, Cladistics 19, 23-90). Moreover, the phylogenetic results of the Frost et al. study were largely consistent with previous morphological and molecular studies and where they differed, this was discussed with reference to the weight of evidence. (3) The claim that equally weighted parsimony assumes that all characters are evolving at equal rates has been shown to be false in both analytical and simulation studies. (4) The claimed strong support for marsupial frog monophyly is questionable. Several studies have also found marsupial frogs to be non-monophyletic. Wiens et al. (2005, Syst. Biol. 54, 719-748) recovered marsupial frogs as monophyletic, but that result was strongly supported only by Bayesian clade confidence values (which are known to overestimate support) and bootstrap support in his parsimony analysis was < 50%. Further, in a more recent parsimony analysis of an expanded data set that included RAG-1 and the three traditional morphological synapomorphies of marsupial frogs, Wiens et al. (2006, Am. Nat. 168, 579-596) also found them to be non-monophyletic.Although we attempted to apply the rule of monophyly to the naming of taxonomic groups, our phylogenetic results are largely consistent with conventional views even if not wth the taxonomy current at the time of our writing. Most of our taxonomic changes addressed examples of non-monophyly that had previously been known or suspected (e.g., the non-monophyly of traditional Hyperoliidae, Microhylidae, Hemiphractinae, Leptodactylidae, Phrynobatrachus, Ranidae, Rana, Bufo; and the placement of Brachycephalus within Eleutherodactylus, and Lineatriton within Pseudoeurycea), and it is troubling that Wiens and others, as evidenced by recent publications, continue to perpetuate recognition of non-monophyletic taxonomic groups that so profoundly misrepresent what is known about amphibian phylogeny. (C) The Willi Hennig Society 2007.

Connection coefficients and zeros of orthogonal polynomials

We discuss an old theorem of Obrechkoff and some of its applications. Some curious historical facts around this theorem are presented. We make an attempt to look at some known results on connection coefficients, zeros and Wronskians of orthogonal polynomials from the perspective of Obrechkoff's theorem. Necessary conditions for the positivity of the connection coefficients of two families of orthogonal polynomials are provided. Inequalities between the kth zero of an orthogonal polynomial p(n)(x) and the largest (smallest) zero of another orthogonal polynomial q(n)(x) are given in terms of the signs of the connection coefficients of the families {p(n)(x)} and {q(n)(x)}, An inequality between the largest zeros of the Jacobi polynomials P-n((a,b)) (x) and P-n((alpha,beta)) (x) is also established. (C) 2001 Elsevier B.V. B.V. All rights reserved.

INEQUALITIES FOR ZEROS of JACOBI POLYNOMIALS VIA OBRECHKOFF'S THEOREM

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Electron microprobe and Raman spectroscopic investigation of monazite from chromitites of Cedrolina (Goias State, Brazil)

Monazite from chromitites of Cedrolina (Goias State, Brazil) was investigated by electron microprobe and Raman spectroscopy. Monazite has been rarely encountered in chromitites. In Brazil, it was previously reported from chromitites of the Campo Formoso layered intrusion. Comparison between the two occurrences indicates similar morphology and textural characteristics, but remarkable differences in chemical composition. In both cases, monazite occurs as irregular grains (up to 200 mu m) preferentially located in the chlorite-serpentine matrix of the chromitite, more rarely included in chromite. However, the monazite from Cedrolina is characterized by higher Ce/La ratio, and Pr, Nd, Th contents, compared with the monazite from Campo Formoso. The obtained Raman spectra are very similar in the two cases, suggesting that the compositional variation of monazites and the spectral resolution of the Raman do not allow a conclusive chemical analysis with Raman spectra. Textural evidence indicates that, in both occurrences, monazite precipitation did not take place at high temperature, concomitantly with the host chromitite. In the Campo Formoso chromitites, precipitation of monazite has been related with percolation of hydrothermal, aqueous and acid fluids emanating from a granite batholith. on the contrary, the Cedrolina monazite probably formed during one of the metamorphic events that affected the area in which the host chromitite occurs.

Structural investigations of tungsten silver phosphate glasses by solid state NMR, vibrational and X-ray absorption near edge spectroscopies

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Microstructural investigation of the PZT films prepared from the suspension of nanocrystalline powders

PZT thin films of composition Pb(Zr0.52Ti0.48)O-3 were prepared by a novel method from the suspension of nanocrystalline PZT powders. The powders were obtained by mechanochemical synthesis. Films were deposited on silicon (100) and platinum covered silicon substrates (Pt (111) /Ti/SiO2/Si) Using spin-on technique. Substrate type has influence on films crystallinity, orientation and can react with the films changing its phase composition. Films microstructure strongly depends on thermal treatment conditions due to phase and compositional changes of the films. (C) 2003 Elsevier Ltd. All rights reserved.

A CHEBYSHEV-TYPE QUADRATURE RULE WITH SOME INTERESTING PROPERTIES

We give here an n-point Chebyshev-type rule of algebraic degree of precision n - 1, but having nodes that can be given explicitly. This quadrature rule also turns out to be one with an ''almost'' highest algebraic degree of precision.

Density improvement of the sol-gel dip-coated SnO2 films by chemical surface modification

We compare the effect of organic (Tiron (R)) and inorganic (Mn(11)) additives on the low temperature (< 600 degrees C) densification of the sol-gel dip-coated SnO2 films. The structural and compositional properties of the samples were investigated by X-ray reflectometry (XRR), X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS). The results suggest that the replacement of hydroxyl groups at the particle surface by Tiron (R) reduces the level of agglomeration of the sol, increasing the particles packing and the apparent density of the coatings. Undoped and Mn-doped films drawn from a Tiron (R) containing suspension show after firing at 500 degrees C a porosity reduction of 12 and 8.6%, respectively. The porosity decrease is less pronounced (4.3%) for the film without additives. Both XAS and XPS data show the presence of trivalent manganese. The formation of a non-homogeneous solid solution characterised by the presence of Mn(111) replacing tin atom near to the crystallite surface was evidenced by XAS. Additionally, XPS results reveal the presence of metallic Sn at the surface of films containing Tirono. (c) 2005 Elsevier Ltd. All rights reserved.