Highly selective nickel ethylene oligomerization catalysts based on sterically hindered tris(pyrazolyl)borate ligands

The reaction of TlTp' (Tp' = HB(3-mesitylpyrazolyl)(3)(-) (Tp(Ms)), HB(3-mesitylpyrazolyl)(2)(5-mesitylpyrazolyl)(-) (Tp(Ms)*)) with NiCl(2).6H(2)O affords Tp(Ms)NiCl (1) and Tp(Ms)*NiCl (2) in good yield. The compound 2 undergoes an isomerization process to form [{Tp(Ms)**}NiCl](2) (3) (Tp(Ms)** = HB(5-mesitylpyrazolyl)(2)(3-mesitylpyrazolyl)(-)) in 68% yield. Treatment of the tris(pyrazolyl)-borate nickel compounds 1 and 2 with alkylaluminum cocatalysts such as methylalumoxane (MAO) and trimethylaluminum (TMA) in toluene generates active catalysts for ethylene oligomerization. The compound 1 shows turnover frequencies in the range of (2.2-43.1) x 10(3) h(-1). Oligomerization reaction conditions can be adjusted that lead to selectivities as high as 81% for butene-1.

Effects of selective logging on the mating system and pollen dispersal of Hymenaea courbaril L. (Leguminosae) in the Eastern Brazilian Amazon as revealed by microsatellite analysis

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Feeding ecology of a selective folivore, the thin-spined porcupine (Chaetomys subspinosus) in the Atlantic forest

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

Assessment of tropical forest degradation by selective logging and fire using Landsat imagery

Many studies have assessed the process of forest degradation in the Brazilian Amazon using remote sensing approaches to estimate the extent and impact by selective logging and forest fires on tropical rain forest. However, only a few have estimated the combined impacts of those anthropogenic activities. We conducted a detailed analysis of selective logging and forest fire impacts on natural forests in the southern Brazilian Amazon state of Mato Grosso, one of the key logging centers in the country. To achieve this goal a 13-year series of annual Landsat images (1992-2004) was used to test different remote sensing techniques for measuring the extent of selective logging and forest fires, and to estimate their impact and interaction with other land use types occurring in the study region. Forest canopy regeneration following these disturbances was also assessed. Field measurements and visual observations were conducted to validate remote sensing techniques. Our results indicated that the Modified Soil Adjusted Vegetation Index aerosol free (MSAVI(af)) is a reliable estimator of fractional coverage under both clear sky and under smoky conditions in this study region. During the period of analysis, selective logging was responsible for disturbing the largest proportion (31%) of natural forest in the study area, immediately followed by deforestation (29%). Altogether, forest disturbances by selective logging and forest fires affected approximately 40% of the study site area. Once disturbed by selective logging activities, forests became more susceptible to fire in the study site. However, our results showed that fires may also occur in undisturbed forests. This indicates that there are further factors that may increase forest fire susceptibility in the study area. Those factors need to be better understood. Although selective logging affected the largest amount of natural forest in the study period, 35% and 28% of the observed losses of forest canopy cover were due to forest fire and selective logging combined and to forest fire only, respectively. Moreover, forest areas degraded by selective logging and forest fire is an addition to outright deforestation estimates and has yet to be accounted for by land use and land cover change assessments in tropical regions. Assuming that this observed trend of land use and land cover conversion continues, we predict that there will be no undisturbed forests remaining by 2011 in this study site. Finally, we estimated that 70% of the total forest area disturbed by logging and fire had sufficiently recovered to become undetectable using satellite data in 2004. (C) 2010 Elsevier B.V. All rights reserved.

Localization of Antigenic Sites in Unfed Nymphs of Amblyomma triste Koch 1844 (Acari: Ixodidae) Ticks by Immunohistochemistry

P>The reactivity of sera collected from guinea pigs after three infestations with Amblyomma triste nymphs on histological sections of the same tick species was investigated through immunohistochemistry to identify potential target cells and tissues. Six guinea pigs were infested thrice, at 30 day intervals, with 30 nymphs of A. triste per animal per infestation. Blood samples were collected from the guinea pigs 15 days after each infestation for serum separation; normal serum was obtained before the first infestation as control. Unfed A. triste nymphs' histological sections were submitted to indirect immunohistochemistry technique by using normal or hyperimmune guinea pig serum as primary antibody and a goat IgG-alkaline phosphatase-APase conjugate as secondary antibody. A weak to moderate APase activity was observed in cells of salivary glands, midgut and haemolymph of unfed nymphs incubated with hyperimmune serum.

Fermion localization on degenerate and critical branes

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Selective UV-filter detection with sensors based on stainless steel electrodes modified with polyaniline doped with metal tetrasulfonated phthalocyanine films

This work describes the construction and application of two amperometric sensors for sensitive UV-filter determination. The sensors were prepared using stainless steel electrodes in which polyaniline (PANI) was electrochemically polymerized in the presence of nickel (NiPcTS) or iron (FePcTS) tetrasulfonated phthalocyanines. The sensor surface characterizations were carried out using atomic force microscopy (AFM). The PANI/NiPcTS sensor was selective for the chemical UV-filter p-aminobenzoic acid (PABA) and the PANI/FePcTS sensor was selective for octyldimethyl-PABA (ODP), both in a mixture of tetrahydrofuran (THF) and 0.1 mol L(-1) H(2)SO(4) at a volume ratio of 30 : 70, and with an applied potential of 0.0 mV vs. Ag vertical bar AgCl. A detailed investigation of the selectivity was carried out for both sensors, in order to determine their responses for ten different UV filters. Finally, each sensor was successfully applied to PABA or ODP quantification in sunscreen formulations and water from swimming pools.

Detection and localization of small nuclear ribonucleoproteins (snRNPs) in trypanosomatids using anti-m(3)G antibodies

This work reports for the first time the identification and immunolocalization, by confocal and conventional indirect immunofluorescence, of m(3)G epitopes present in ribonucleoproteins of the following trypanosomatids: Trypanosoma cruzi epimastigotes of three different strains, Blastocrithidia ssp., and Leishmania major promastigotes. The identity of these epitopes and hence the specificity of the anti-m(3)G monoclonal antibody were ascertained through competition reaction with 7-methylguanosine that blocks the Ig binding sites, abolishing the fluorescence in all the parasites tested and showing a specific perinuclear localization of the snRNPs, which suggests their nuclear reimport in the parasites. Using an immunoprecipitation technique, it was also possible to confirm the presence of the trimethylguanosine epitopes in trypanosomatids.

Electrochemical sensor highly selective for estradiol valerate determination based on a modified carbon paste with iron tetrapyridinoporphyrazine

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Localization and hormonal regulation of endometrial matrix metalloproteinase-26 in the rhesus macaque

The current understanding of hormonal regulation of matrix metalloproteinase-26 (MMP-26) in the primate endometrium is incomplete. The goal of this work was to clarify estrogen and progesterone regulation of MMP-26 in the endometrium of ovariectomized, hormone-treated rhesus macaques.Ovariectomized rhesus macaques (n 66) were treated with estradiol (E-2), E-2 plus progesterone, E-2 followed by progesterone alone or no hormone. Endometrium was collected from the hormone-treated animals during the early, mid- and late proliferative and secretory phases of the artificial menstrual cycle. MMP-26 expression was quantified by real-time PCR, and MMP-26 transcript and protein were localized by in situ hybridization and immunohistochemistry and correlated with estrogen receptor 1 and progesterone receptor (PGR).MMP-26 was localized to glandular epithelium and was undetectable in the endometrial stroma and vasculature. MMP-26 transcript levels were minimal in the hormone-deprived macaques and treatment with E-2 alone did not affect MMP-26 levels. Treatment with progesterone both in the presence and absence of E-2 stimulated MMP-26 expression in the early and mid-secretory phases (P 0.001). MMP-26 expression preceded decidualization of endometrial stroma. MMP-26 levels then declined to baseline in the late secretory phase (P 0.01) despite continued E-2 plus progesterone treatment. Loss of detectable MMP-26 expression in the late secretory phase was correlated with late secretory phase loss of glandular epithelial PGR.Endometrial MMP-26 expression is dependent on the presence of progesterone in the early secretory phase and then gradually becomes refractory to progesterone stimulation in the late secretory phase. In the macaque, MMP-26 is a marker of the pre-decidual, secretory endometrium. During the second half of the late secretory phase, and during decidualization, MMP-26 loses its response to progesterone concurrent with the loss of epithelial PGR. The decline in MMP-26 levels between the mid- and late secretory phases may play a role in the receptive window for embryo implantation.

Critical exponents for a transition from integrability to non-integrability via localization of invariant tori in the Hamiltonian system

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Selective Ablation of the Androgen Receptor in Mouse Sertoli Cells Affects Sertoli Cell Maturation, Barrier Formation and Cytoskeletal Development

The observation that mice with a selective ablation of the androgen receptor (AR) in Sertoli cells (SC) (SCARKO mice) display a complete block in meiosis supports the contention that SC play a pivotal role in the control of germ cell development by androgens. To delineate the physiological and molecular mechanism responsible for this control, we compared tubular development in pubertal SCARKO mice and littermate controls. Particular attention was paid to differences in SC maturation, SC barrier formation and cytoskeletal organization and to the molecular mediators potentially involved. Functional analysis of SC barrier development by hypertonic perfusion and lanthanum permeation techniques and immunohistochemical analysis of junction formation showed that SCARKO mice still attempt to produce a barrier separating basal and adluminal compartment but that barrier formation is delayed and defective. Defective barrier formation was accompanied by disturbances in SC nuclear maturation (immature shape, absence of prominent, tripartite nucleoli) and SC polarization (aberrant positioning of SC nuclei and cytoskeletal elements such as vimentin). Quantitative RT-PCR was used to study the transcript levels of genes potentially related to the described phenomena between day 8 and 35. Differences in the expression of SC genes known to play a role in junction formation could be shown from day 8 for Cldn11, from day 15 for Cldn3 and Espn, from day 20 for Cdh2 and Jam3 and from day 35 for ZO-1. Marked differences were also noted in the transcript levels of several genes that are also related to cell adhesion and cytoskeletal dynamics but that have not yet been studied in SC (Actn3, Ank3, Anxa9, Scin, Emb, Mpzl2). It is concluded that absence of a functional AR in SC impedes the remodeling of testicular tubules expected at the onset of spermatogenesis and interferes with the creation of the specific environment needed for germ cell development.

Positioning and localization of two-wavelength interferograms for wavefront reconstruction with volume holographic media

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)