Local Structure and Photochromic Response in Ormosils Containing Dodecatungstophosphoric Acid

Two hybrid materials based on dodecatungstophosphoric acid (HPW) dispersed in ormosils modified with 3-aminopropiltrietoxysilane (APTS) or with N-(3-(trimethoxysilyl)-propyl)-ethylene-diamine (TSPEN) show reversible photochromic response induced by irradiation in the 200-390 nm UV range. A set of solid-state nuclear magnetic resonance (NMR) techniques was used to analyze the structural properties of the main components of these hybrids (the HPW polyanion, the inorganic matrix, and the organic functionalities). For the ormosils, the use of (29)Si NMR, {(1)H}-(29)Si cross-polarization, and {(1)H}-(29)Si HETCOR revealed a homogeneous distribution of silicon species Q ``, T(2), and T(3) for the APTS hybrid, contrasting with the separation of T(3) species in the TSPEN hybrid. The combination of (31)P NMR, {(1)H}-(31)P cross-polarization and (31)P-{(1)H} spin-echo double resonance (SEDOR) revealed the dispersion of the HPW ions in the ormosil, occupying sites with a high number of close protons (>50). Differences in the molecular dynamics at room temperature, inferred from SEDOR experiments, indicate a state of restricted mobility of the HPW ion and the surrounding molecular groups in the TSPEN hybrid. This behavior is consistent with the presence of more amino groups in the TSPEN, acting as chelating groups to the HPW ion. This hybrid, with the strong chelate interaction of the diamine group, shows the most intense photochromic response, in agreement with the charge transfer models proposed to explain the photochromic effect. Electronic reflectance spectroscopy in irradiated samples revealed the presence of one-electron and two-electron reduced polyanions. The one-electron reduced species could be detected also by (31)P NMR spectroscopy immediately after UV irradiation.

Oxotechnetium(V) Complexes with a Novel Class of Tridentate Thiosemicarbazide Ligands

A novel tridentate thiosemicarbazide-type ligand class with an SNS donor set, H(2)L(1), was prepared by reactions of N-[N`,N`-dialkylamino(thiocarbonyl)]benzimidoyl chlorides with thiosemicarbazides. H(2)L(1) ligands readily react with (NBu(4))[TcOCl(4)] in MeOH under the formation of red oxotechnetium(V) complexes of composition [TcOCl(L(1))]. The monomeric, five-coordinate compounds are air-stable and bind (L(1))(2-) tridentate in the equatorial coordination sphere. The compounds represent the first examples of oxotechnetium(V) complexes with NS chelate-bonded thiosemicarbazones.

Bioprospecção de polissacarídeos sulfatados de macroalgas marinhas do litoral do Rio Grande do Norte: caracterização de uma heterofucana extraída da alga marron sargassum filipendula que induz apoptose em células hela

The coast of Rio Grande do Norte has more than 100 species of seaweed, mostly unexplored regarding their pharmacological potential. The sulfated polysaccharides (PS) are by far the more seaweed compounds studied, these present a range of biological properties, such as anticoagulant activity, anti-inflammatory, antitumor and antioxidant properties. In this study, we extract sulfated polysaccharide rich-extracts of eleven algae from the coast of Rio Grande do Norte (Dictyota cervicornis; Dictiopterys delicatula; Dictyota menstruallis; Dictyota mertensis; Sargassum filipendula; Spatoglossum schröederi; Gracilaria caudata; Caulerpa cupresoides; Caulerpa prolifera; Caulerpa sertularioides e Codim isthmocladum), and these were evaluated for the potential anticoagulant, antioxidant and antiproliferative. All polysaccharide extracts showed activity for anticoagulant, antioxidant and/or antiproliferative activity, especially D. delicatula and S. filipendula, which showed the most prominent pharmacological potential, thereby being chosen to have their sulfated polysaccharides extracted. By fractionating method were obtained six fractions rich in sulfated polysaccharides to the algae D. delicatula (DD-0,5V, DD-0, 7V, DD-1,0v, DD-1,3v, DD-1,5v and DD-2,0) and five fractions to the alga S. filipendula (SF-0,5V, SF-0,7V, SF-1,0v, SF-1,5v and SF-2,0v). For the anticoagulant assay only the fractions of D. delicatula showed activity, with emphasis on DD-1, 5v that presented the most prominent activity, with APTT ratio similar to clexane® at 0.1 mg/mL. When evaluated the antioxidant potential, all fractions showed potential in all tests (total antioxidant capacity, hydroxyl and superoxide radicals scavenging, ferrous chelation and reducing power), however, the ability to chelate iron ions appears as the main mechanism antioxidant of sulfated polysaccharides from seaweed. In antiproliferative assay, all heterofucanas showed dose-dependent activity for the inhibition of cell proliferation of HeLa, however, with the exception of SF-0,7V, SF- 1,0v and SF-1,5v, all fractions showed antiproliferative activity against MC3T3, a normal cell line. The heterofucana SF-1,5V had its antiproliferative mechanism of action evaluated. This heterofucan induces apoptosis in HeLa cells by a pathway caspase independent, promoting the release of apoptosis Inducing Factor (AIF) in the cytosol, which in turn induces chromatin condensation and DNA fragmentation into 50Kb fragments. These results are significant in that they provide a mechanistic framework for further exploring the use of SF-1.5v as a novel chemotherapeutics against human cervical cancer.

Manganês e potencial fisiológico de sementes de soja

O trabalho teve por objetivo avaliar a influência de diferentes fontes e modos de aplicação de manganês, em plantas de soja, sobre o potencial fisiológico das sementes produzidas e a massa de mil sementes. Os tratamentos constaram de fontes de manganês aplicadas via solo (MnSO4.4H2O e Oxi-sulfato Mn) e via foliar (MnSO4.4H2O, Quelado Cl-, Quelado NO3- e Quelado SO4(2-)); para as sementes produzidas, determinaram-se a massa de mil sementes, a germinação e o vigor (envelhecimento acelerado e condutividade elétrica). Diante dos resultados obtidos, concluiu-se que a aplicação de manganês exerceu influência positiva sobre a massa das sementes de soja produzidas e que o estado nutricional das plantas, em relação ao manganês, não influenciou o potencial fisiológico das sementes produzidas.

Organic and inorganic sources of zinc, copper and selenium in diets for dairy cows: intake, blood metabolic profile, milk yield and composition

The present study was carried out with the objective of evaluating the effects of feeding dairy cows with organic or inorganic sources of zinc (Zn), copper (Cu) and selenium (Se) on blood concentrations of these minerals, blood metabolic profiles, nutrient intake and milk yield and composition. Nineteen Holstein cows were selected and randomly assigned to two groups for receiving organic (n = 9) or inorganic (n = 10) sources of Zn, Cu and Se from 60 days before the expected date of calving to 80 days of lactation. Samples of feed, orts and milk were collected for analysis. Body condition score (BCS) was determined and blood samples were collected for analysis of Zn, Cu and Se concentrations, as well as for metabolic profile. Supplying organic or inorganic sources of Zn, Cu, and Se did not affect dry matter and nutrient intake, blood metabolic profile, milk yield and composition, plasma concentration of these minerals, and BCS or change the BCS in cows from 60 days before the expected date of calving to 80 days of lactation. An effect of time was observed on all feed intake variables, plasma concentrations of Zn and Se, milk yield, milk protein content, BCS and change in BCS.

Phytase immobilization on modified electrodes for amperometric biosensing

Phytase (myo-inositol hexaphosphate phosphohydrolase) and phytic acid (myo-inositol hexaphosphate) play an important environmental role, in addition to being a health issue in food industry. Phytic acid is antinutritional due to its ability to chelate metal ions and may also react with proteins decreasing their bioavailability. In this work, we produced biosensors with phytase immobilized in Layer-by-Layer (LbL) films, which could detect phytic acid with a detection limit of 0.19 mmol L-1, which is sufficient to detect phytic acid in seeds of grains and vegetables. The biosensosrs consisted of LbL films containing up to eight bilayers of phytase alternated with poly(allylamine) hydrochloride (PAH) deposited onto an indium-tin oxide (ITO) substrate modified with Prussian Blue. Amperometric detection was conducted in an acetate buffer solution (at pH 5.5) at room temperature, with the biosensor response attributed to the formation of phosphate ions. In subsidiary experiments with the currents measured at 0.0 V (vs. SCE), we demonstrated the absence of effects from some interferents, pointing to a good selectivity of the biosensor. (c) 2007 Elsevier B.V. All rights reserved.

Development on polymeric precursor routes to produce superconducting nanoparticles

The well-known polymeric precursor route is a simple and low-cost sol-gel method based on the preparation of an aqueous precursor solution of metals followed by the addition of a water-soluble polymer. This method consists of a polyesterification process between a metal chelate complex by using a hydroxycarboxylic acid and a polyhydroxy alcohol. In this work, citric acid (CA), tartaric acid (TA) and ethylenediaminetetraacetic acid (EDTA) are used as the hydroxycarboxylic acid and ethylene glycol (EG) is used as the polyhydroxy alcohol. The effects of the precursor pH solution, time and temperature of polymerization step as well as the combination of different chelating agents in order to obtain nanoscopic YBa2Cu3Oy samples were traced. (c) 2007 Elsevier B.V. All rights reserved.

Estudo teórico QTAIM e DFT dos compostos de coordenação: efeito quelato, titanocenos e ligação química

This work is a study of coordination compounds by quantum theory of atoms in molecules (QTAIM), based on the topological analysis of the electron density of molecular systems, both theoretically and experimentally obtained. The coordination chemistry topics which were studied are the chelate effect, bent titanocene and chemical bond in coordination complexes. The chelate effect was investigated according to topological and thermodynamic parameters. The exchange of monodentate ligands on polydentate ligands from same transition metal increases the stability of the complex both from entropy and enthalpy contributions. In some cases, the latter had a higher contribution to the stability of the complex in comparison with entropy. This enthalpic contribution is explained according to topological analysis of the M-ligand bonds where polidentate complex had higher values of electron density of bond critical point, Laplacian of electron density of bond critical point and delocalization index (number of shared electrons between two atoms). In the second chapter, was studied bent titanocenes with bulky cyclopentadienyl derivative π-ligand. The topological study showed the presence of secondary interactions between the atoms of π-ligands or between atoms of π-ligand and -ligand. It was found that, in the case of titanocenes with small difference in point group symmetry and with bulky ligands, there was an nearly linear relationship between stability and delocalization index involving the ring carbon atoms (Cp) and the titanium. However, the titanocene stability is not only related to the interaction between Ti and C atoms of Cp ring, but secondary interactions also play important role on the stability of voluminous titanocenes. The third chapter deals with the chemical bond in coordination compounds by means of QTAIM. The quantum theory of atoms in molecules so far classifies bonds and chemical interactions in two categories: closed shell interaction (ionic bond, hydrogen bond, van der Waals interaction, etc) and shared interaction (covalent bond). Based on topological parameters such as electron density, Laplacian of electron density, delocalization index, among others, was classified the chemical bond in coordination compounds as an intermediate between closed shell and shared interactions

Foliar Fertilization on pineapple quality and yield

Poucos são os estudos desenvolvidos com a aplicação via foliar de micronutrientes, na cultura do abacaxi. Este trabalho teve como objetivo avaliar os efeitos de B e Zn, em forma de quelato, ácido ou sal, via foliar, buscando-se obter respostas sobre os efeitos na produtividade e qualidade dos frutos. O experimento foi realizado em Guaraçaí (SP), em solo com textura média. Foram utilizadas mudas tipo filhote, da cultivar Smooth Cayenne (Havaiano). O delineamento experimental adotado foi o de blocos ao acaso, com quatro repetições, utilizando-se fontes para fornecer, em cada aplicação, 110 g ha-1de B e 250 g ha-1de Zn. Foram realizadas duas pulverizações foliares, aos 7 e 9 meses após o plantio. As fontes de B e Zn não exerceram efeito nos teores de sólidos solúveis totais, acidez titulável, diâmetro médio do fruto, comprimento do fruto sem coroa e índice de maturação. Apenas os teores de B, Zn e K, na folha, foram influenciados pelos tratamentos utilizados.

Biodisponibilidade de ferro em diferentes compostos para leitões desmamados aos 21 dias de idade

Avaliou-se a biodisponibilidade de ferro de diferentes compostos visando sua utilização em dietas para leitões desmamados. Utilizaram-se 44 leitões (7 não-anêmicos e 37 anêmicos) desmamados aos 21 dias de idade (7,3 ± 1,8 kg) e distribuídos em dois grupos: grupo não-anêmico e grupo anêmico. Durante sete dias, os animais do grupo não-anêmico receberam dieta com FeSO4.7H2O (sulfato ferroso hepta-hidratado) na dose de 100 mg/kg e os do grupo anêmico, dieta sem ferro (<15 mg/kg ração). No sétimo dia, depois de determinada a concentração de hemoglobina sanguínea e diagnosticada a anemia, os leitões foram agrupados segundo o produto do peso (kg) × hemoglobina (g/dL) e alojados individualmente, durante 13 dias, em gaiolas para estudos de digestibilidade, onde foram alimentados com seis rações à base de milho e leite em pó: três rações-padrão com FeSO4.7H2O em quantidade equivalente a 80, 150 e 200 mg Fe/kg de ração; duas rações experimentais com ferro (150 mg/kg) na forma de FeSO4 microencapsulado com carboximetilcelulose ou de ferro quelado com metionina; e uma controle com ferro (100 mg/kg). O consumo de ração foi medido diariamente. Nos dias 0, 3, 6, 9 e 13 do período de repleção, os animais foram pesados para avaliação do desempenho e o sangue foi coletado para determinação da concentração de hemoglobina. Ao final do ensaio, os animais foram sacrificados e o fígado foi coletado para determinação das concentrações de ferro total, ferro heme e ferro não-heme. As concentrações hepáticas de ferro heme, ferro não-heme e ferro total não diferiram entre os animais, entretanto, os do grupo controle apresentaram excesso de ferro total no fígado, relacionado à dose de ferro injetada nos leitões após o desmame. em comparação ao FeSO4.7H2O não encapsulado, os compostos de ferro microencapsulado com carboximetilcelulose e de ferro quelado com metionina promovem melhor conversão alimentar em leitões desmamados.

Micromorphology and spectroscopic characteristics of organic matter in waterlogged podzols of the upper Amazon basin

In waterlogged environments of the upper Amazon basin, organic matter is a major driver in the podzolisation of clay-depleted laterites, especially through its ability to weather clay minerals and chelate metals. Its structure in eight organic-rich samples collected at the margin and in the centre of the podzolic area of a soil sequence was investigated. The samples illustrate the main steps in the development of waterlogged podzols and belong either to eluviated topsoil A horizons or to illuviated subsoil Bhs, Bh and 2BCs horizons. Organic matter micromorphology was described, and the overall molecular structure of their clay size fractions was assessed using Fourier transform infrared (FTIR) spectroscopy and cross polarization/magic angle spinning (CP/MAS) C-13 nuclear magnetic resonance (NMR). Organic features of the horizons strongly vary both vertically and laterally in the sequence. Topsoil A horizons are dominated by organic residues juxtaposed to clean sands with a major aliphatic contribution. In the subsoil, numerous coatings, characteristic of illuviation processes, are observed in the following horizons: (i) At the margin and bottom parts of the podzolic area, dark brown organic compounds of low aromacity with abundant oxygen-containing groups accumulate in Bhs and 2BCs horizons. Their spectroscopic features agree with the observation of cracked coatings in 2BCs and the presence of organometallic complexes, whose abundance decreases towards low lying positions. (ii) By contrast, black organic compounds of high aromacity with few chelating functions accumulate as coatings and infills in the overlying sandy Bh horizon of well-expressed waterlogged podzols. (c) 2008 Elsevier B.V. All rights reserved.

Synthesis and characterization of antimony tartrate for ceramic precursors

Synthesis and characterization of antimony tartrate used as a precursor of ceramic powders obtained by Pechini's method were carried out. Antimony tartrate was chosen as a substitute for the antimony citrate commonly used in this chemical processing, because of difficulties in preparing the citrate. FTIR and TGA/DTA analysis showed that antimony tartrate, H-2[Sb-2(C4H2O6)(2)]. forms a polymeric structure. The procedure described indicates that the antimony chelate obtained is adequate for Pechini's method.

Preparação e caracterização do complexo sólido de estanho(II)-EDTA e influência do tratamento térmico sobre a morfologia do resíduo SnO2

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Produtividade e desenvolvimento da cana-planta e soca em função de doses e fontes de manganês

A cana-de-açúcar possui grande importância econômico-social e política para o Brasil. Este trabalho teve como objetivo avaliar o efeito de doses e fontes de manganês nessa cultura. O experimento foi realizado no sítio Fujimoto, área administrada pela Destilaria Vale do Paraná S/A Álcool e Açúcar, no município de Suzanápolis, SP. O delineamento experimental utilizado foi o de blocos ao acaso no esquema fatorial 5 x 3, sendo cinco doses de Mn (0; 2,5; 5,0; 7,5; e 10,0 kg ha-1) e três fontes (quelato, FTE e sulfato de manganês), aplicadas no sulco de plantio, em quatro repetições. As parcelas foram constituídas por quatro linhas de 5 m de comprimento e espaçadas 1,5 m. A variedade de cana-de-açúcar utilizada foi a RB 86-7515, realizando-se dois cortes. As fontes de Mn proporcionaram semelhantes produtividades de colmos, tanto da cana-planta quanto da primeira cana-soca. O quelato de Mn proporcionou maior número de colmo por metro de sulco na cana-soca. As doses de Mn não influenciaram a produtividade de colmos da cana-planta e da cana- soca, porém aumentaram o número de internódios e o diâmetro de colmo na cana-planta até as doses de 6,9 e 6,6 kg ha-1 de Mn, respectivamente.

Adubação foliar. I. Épocas de aplicação de fósforo na cultura da soja

The search for new alternatives in order to increase soybeans productivity has been constant objective of researchers and farmers. The crop responses to phosphorus application in the soil are well defined, being this nutrient very important on its development and yield. The leaf fertilization on this crop appears as a new rationale option, mainly when the plant nutrient levels are low. So, this work aimed to study the effect of phosphorus leaf fertilization, applied at different plant stage, including: V5, R1, R4, V5 + R1, V5 + R4, R1 + R4, V5 + R1 + R4, V5 + R1 + R4 + R6 and test plot. The experiment was installed in a soybeans crop, Monarca cultivar, at Palmital Farm, Ijaci county, Minas Gerais state, Brazil, using a totally randomized design, with 9 treatments and 3 replications. The chelate Quimifol P30 in liquid form with 30% of the nutrient soluble in CNA + water in the, with doses of 21. ha(-1), was utilized as phosphorus source, using the applications performed with a constant pressure CO(2)-nebulizer. The different epochs of phosphorous application significantly altered the grains yield, proportioning significant increases, up to 16% for the V5, V5 + R1, V5 + R4, V5 + R1 + R4, V5 + R1 + R4 + R6 epochs, when compared to the test plot, clearly expressing the positive effect of these applications at V5 stage. The plant height, first legume insertion, and lodging index characteristics were not significantly altered by the different epochs evaluated. It was observed significant response for the nutrient leaf amounts only in the case of K and Zn indices, exclusively in the V5 + R4, and in the V5, V5 + R1 and V5 + R1 + R4 + R6 treatments, respectively.