Thermogravimetric studies of the decomposition kinetics of four different Hevea rubber clones using Ozawa's approach

Thermal degradation of natural rubber extracted from four different rubber clones of the Hevea brasiliensis species was investigated by thermogravimetry using Ozawa's approach to assess the kinetic parameters of the decomposition process. The results are discussed in terms of the order of reaction, kinetic parameters such as activation energy as a function of conversion degree, and thermal stability for each of the clones.

An active/reactive predispatch model incorporating ramp rate constraints solved by dual decomposition/lagrangian relaxation

The Predispatch model (PD) calculates a short-term generation policy for power systems. In this work a PD model is proposed that improves two modeling aspects generally neglected in the literature: voltage/reactive power constraints and ramp rate constraints for generating units. Reactive power constraints turn the PD into a non-linear problem and the ramp rate constraints couple the problem dynamically in time domain. The solution of the PD is turned into a harder task when such constraints are introduced. The dual decomposition/ lagrangian relaxation technique is used in the solution approach for handing dynamic constraints. As a result the PD is decomposed into a series of independent Optimal Power Flow (FPO) sub problems, in which the reactive power is represented in detail. The solution of the independent FPO is coordinated by means of Lagrange multipliers, so that dynamic constraints are iteratively satisfied. Comparisons between dispatch policies calculated with and without the representation of ramp rate constraints are performed, using the IEEE 30 bus test system. The results point-out the importance of representing such constraints in the generation dispatch policy. © 2004 IEEE.

Correlated matings in dioecious tropical tree, Myracrodruon urundeuva fr. all.

The correlated matings in two populations (Selvíria - SEL and Paulo de Faria - PFA) of dioecious Myracrodruon urundeuva were studied in the Southwest of Brazil, by allozyme analysis of progeny arrays using the sibling-pair model. Open-pollinated seeds were collected from 25 to 30 trees within populations. Departure from random matings were evident from the differences in pollen and ovule allele frequencies. The high and significant correlation of paternity (SEL r̂p = 0.671 ± 0.074; PFA r̂p = 0.371 ± 0.062) and a low number of effective pollinating trees (ranging from 2 to 3) were detected in the populations, suggesting high proportion of full-sibs progenies. According to these results, the estimate of coancestry within families (θ = 0.209 - SEL; θ = 0.171 - PFA.) exceeded the expectation of the half-sib progenies (θ = 0.125). Result outcomes are discussed from a conservation and breeding point of view.

Spinodal decomposition in pure-gauge QCD

Spinodal decomposition in a model of pure-gauge SU(2) theory that incorporates a deconfinement phase transition is investigated by means of real-time lattice simulations of the fully nonlinear Ginzburg-Landau equation. Results are compared with a Glauber dynamical evolution using Monte Carlo simulations of pure-gauge lattice QCD. © 2005 American Institute of Physics.

Thermal decomposition of palladium(ii) pyrazolyl complexes: Part II

Thermal behavior of pyrazolyl complexes [PdCl2(HPz)2] (1), [PdCl2(HdmPz)2] (2), [Pd(SCN)2(HPz) 2] (3), [Pd(SCN)2(HdmPz)2] (4), [Pd(N 3)2(HdmPz)2] (5), [Pd(PzNHCO)2] (6) and [Pd(dmPzNHCO)2] (7) (HPz=pyrazole, HdmPz=3,5-dimethylpyrazole) has been studied by TG and DTA. In general, the thermal stability of [PdX 2(HL)2] (HL=HPz, HdmPz) compounds varies in the following order: HdmPz>HPz as well, according to the trends X=Cl ->SOT->NNN-. Except for 5, the [PdX 2(HL)2] complexes showed higher thermal stability than the 6 and 7 chelates. No stable intermediates were isolated during the thermal decompositions because of the overlapping degradation processes. The final products of the thermal decompositions were identified as metallic palladium by X-ray powder diffraction. © 2005 Akadémiai Kiadó, Budapest.

Reproductive phenology of Atlantic forest tree species in Brazil: An eleven year study

This paper describes the reproductive phenorhythms of tree species in a tropical seasonal lowland forest in Southeastern Brazil. Every two weeks, five individuals of 41 species were observed for the occurrence of flowering and fruiting, from May 1982 to December 1992. All phenophases showed high seasonality, when considering the whole set of species, but the amplitude of the cycles was much more variable between years; only 13 species had regular flowering. Infra-annual flowering and fruiting were found in 11 and four species, respectively, while only one species flowered and fruited continually. Supra-annual cycles were observed in four (flowering) and seven (fruiting) species. An increase was observed in number of species and individuals flowering and fruiting from 1990 to 1992, following mainly an elevation in the absolute minimum air temperature. These data suggest a relationship between reproductive phenology and major climatic phenomena like El Niño events and solar activity cycles. © International Society for Tropical Ecology.

Molecular phylogenetic and morphological analyses of Oidium heveae, a powdery mildew of rubber tree

Powdery mildew of rubber tree caused by Oidium heveae is an important disease of rubber plantations worldwide. Identification and classification of this fungus is still uncertain because there is no authoritative report of its morphology and no record of its teleomorphic stage. In this study, we compared five specimens of the rubber powdery mildew fungus collected in Malaysia, Thailand, and Brazil based on morphological and molecular characteristics. Morphological results showed that the fungus on rubber tree belongs to Oidium subgen. Pseudoidium. Nucleotide sequence analysis of the ribosomal DNA internal transcribed spacer (ITS) region and the large subunit rRNA gene (28S rDNA) were conducted to determine the relationships of the rubber powdery mildew fungus and to link this anamorphic fungus with its allied teleomorph. The results showed that the rDNA sequences of the two specimens from Malaysia were identical to a specimen from Thailand, whereas they differed by three bases from the two Brazilian isolates: one nucleotide position in the ITS2 and two positions in the 28S sequences. The ITS sequences of the two Brazilian isolates were identical to sequences of Erysiphe sp. on Quercus phillyraeoides collected in Japan, although the 28S sequences differed at one base from sequences of this fungus. Phylogenetic trees of both rDNA regions constructed by the distance and parsimony methods showed that the rubber powdery mildew fungus grouped with Erysiphe sp. on Q. phillyraeoides with 100% bootstrap support. Comparisons of the anamorph of two isolates of Erysiphe sp. from Q. phillyraeoides with the rubber mildew did not reveal any obvious differences between the two powdery mildew taxa, which suggests that O. heveae may be an anamorph of Erysiphe sp. on Q. phillyraeoides. Cross-inoculation tests are required to substantiate this conclusion. © The Mycological Society of Japan and Springer-Verlag 2005.

Age-age correlation for early selection of rubber tree genotypes in São Paulo State, Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estimation of variance components and prediction of breeding values in rubber tree breeding using the REML/BLUP procedure

The present paper deals with estimation of variance components, prediction of breeding values and selection in a population of rubber tree [Hevea brasiliensis (Willd. ex Adr. de Juss.) Müell.-Arg.] from Rio Branco, State of Acre, Brazil. The REML/BLUP (restricted maximum likelihood/best linear unbiased prediction) procedure was applied. For this purpose, 37 rubber tree families were obtained and assessed in a randomized complete block design, with three unbalanced replications. The field trial was carried out at the Experimental Station of UNESP, located in Selvíria, State of Mato Grosso do Sul, Brazil. The quantitative traits evaluated were: girth (G), bark thickness (BT), number of latex vessel rings (NR), and plant height (PH). Given the unbalanced condition of the progeny test, the REML/BLUP procedure was used for estimation. The narrow-sense individual heritability estimates were 0.43 for G, 0.18 for BT, 0.01 for NR, and 0.51 for PH. Two selection strategies were adopted: one short-term (ST - selection intensity of 8.85%) and the other long-term (LT - selection intensity of 26.56%). For G, the estimated genetic gains in relation to the population average were 26.80% and 17.94%, respectively, according to the ST and LT strategies. The effective population sizes were 22.35 and 46.03, respectively. The LT and ST strategies maintained 45.80% and 28.24%, respectively, of the original genetic diversity represented in the progeny test. So, it can be inferred that this population has potential for both breeding and ex situ genetic conservation as a supplier of genetic material for advanced rubber tree breeding programs. Copyright by the Brazilian Society of Genetics.

Improved Langevin approach to spinodal decomposition in the chiral transition

We use an improved Langevin description that incorporates both additive and multiplicative noise terms to study the dynamics of phase ordering. We perform real-time lattice simulations to investigate the role played by different contributions to the dissipation and noise. Lattice-size independence is assured by the use of appropriate lattice counterterms. © 2006 American Institute of Physics.

Comparative studies of the sample decomposition of green and roasted coffee for determination of nutrients and data exploratory analysis

The contents of some nutrients in 35 Brazilian green and roasted coffee samples were determined by flame atomic absorption spectrometry (Ca, Mg, Fe, Cu, Mn, and Zn), flame atomic emission photometry (Na and K) and Kjeldahl (N) after preparing the samples by wet digestion procedures using i) a digester heating block and ii) a conventional microwave oven system with pressure and temperature control. The accuracy of the procedures was checked using three standard reference materials (National Institute of Standards and Technology, SRM 1573a Tomato Leaves, SRM 1547 Peach Leaves, SRM 1570a Trace Elements in Spinach). Analysis of data after application of t-test showed that results obtained by microwave-assisted digestion were more accurate than those obtained by block digester at 95% confidence level. Additionally to better accuracy, other favorable characteristics found were lower analytical blanks, lower reagent consumption, and shorter digestion time. Exploratory analysis of results using Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) showed that Na, K, Ca, Cu, Mg, and Fe were the principal elements to discriminate between green and roasted coffee samples. ©2007 Sociedade Brasileira de Química.

Visual and acoustic signaling in three species of Brazilian nocturnal tree frogs (anura, hylidae)

Visual communication seems to be widespread among nocturnal anurans, however, reports of these behaviors in many Neotropical species are lacking. Therefore, we gathered information collected during several sporadic field expeditions in central and southern Brazil with three nocturnal tree frogs: Aplastodiscus perviridis, Hypsiboas albopunctatus and H. bischoffi. These species displayed various aggressive behaviors, both visual and acoustic, towards other males. For A. perviridis we described arm lifting and leg kicking; for H. albopunctatus we described the advertisement and territorial calls, visual signalizations, including a previously unreported behavior (short leg kicking), and male-male combat; and for H. bischoffi we described the advertisement and fighting calls, toes and fingers trembling, leg lifting, and leg kicking. We speculate about the evolution of some behaviors and concluded that the use of visual signals among Neotropical anurans may be much more common than suggested by the current knowledge. © 2007 Departamento de Ciências Biológicas.

Autoregressive decomposition and pole tracking applied to vocal fold nodule signals

This letter describes a novel algorithm that is based on autoregressive decomposition and pole tracking used to recognize two patterns of speech data: normal voice and disphonic voice caused by nodules. The presented method relates the poles and the peaks of the signal spectrum which represent the periodic components of the voice. The results show that the perturbation contained in the signal is clearly depicted by pole's positions. Their variability is related to jitter and shimmer. The pole dispersion for pathological voices is about 20% higher than for normal voices, therefore, the proposed approach is a more trustworthy measure than the classical ones. © 2007.

Heating rate and temperature effects on the BaTiO3 formation by thermal decomposition of (Ba,Ti) organic precursors during the Pechini process

Different thermal treatments for the synthesis of BaTiO3 powder obtained through the Pechini method were studied. The synthesis of BaTiO3 starts at 150 °C by the thermal dehydration of organic precursors. The usual inevitable formation of barium carbonate during the thermal decomposition of the precursor could be retarded at lower calcination temperatures and optimized heating rates. The organic precursors were treated at temperatures between 200 and 400 °C. Then, the samples were calcined at 700 and 800 °C for 4 and 2 h, respectively. The resulting ceramic powders were characterized by gravimetric and differential thermal analyses, X-ray powder diffraction and infrared spectroscopy. It was found that depending on the heating rate and final temperature of the thermal treatment, high amounts of BaCO3 and TiO2 could be present due to the high concentration of organics in the final calcination step. © 2007 Elsevier B.V. All rights reserved.