HETEROTIC GROUP FORMATION IN PSIDIUM GUAJAVA L. BY ARTIFICIAL NEURAL NETWORK AND DISCRIMINANT ANALYSIS

ABSTRACT The present study aimed at evaluating the heterotic group formation in guava based on quantitative descriptors and using artificial neural network (ANN). For such, we evaluated eight quantitative descriptors. Large genetic variability was found for the eight quantitative traits in the 138 genotypes of guava. The artificial neural network technique determined that the optimal number of groups was three. The grouping consistency was determined by linear discriminant analysis, which obtained classification percentage of the groups, with a value of 86 %. It was concluded that the artificial neural network method is effective to detect genetic divergence and heterotic group formation.

Spontaneous perforation of gallbladder with intrahepatic biloma formation: sonographic signs and correlation with computed tomography

Spontaneous perforation of gallbladder is a severe and infrequent complication of acute cholecystitis that requires early and accurate diagnosis. Concomitant development of intrahepatic collections is rarely observed in such cases. The present report emphasizes the relevance of imaging studies in this setting, describing the typical sonographic and tomographic findings for the diagnosis of such condition.

Organo-gel: um novo sistema para a imobilização de lipases e sua aplicação em síntese orgânica

Lipases have been immobilized in microemulsion-based organogels (MBG's) and successfully utilized for the enantioselective esterification, diesterification and transesterification reactions, in organic solvents at 25ºC. This methodology is described as a new alternative for the use of enzymes in organic solvents. High enzymic stability has been observed. We have also used this methodology for the successful resolution of chiral secondary alcohols. This is a convenient way of using this catalyst in organic solvents which employs small amounts of the enzyme (250mg/mL).

Optical characterization of sol-gel glasses derived from Eu3+ complex-forming precursors

Fabrication of new optical devices based upon the incorporation of rare earth ions via sol-gel methods depends on elimination of dopant ion clusters and residual hydroxyl groups from the final material. The optical absorption and/or luminescence properties of luminescent rare earth ions are influenced by the local bonding environment and the distribution of the rare-earth dopants in the matrix. Typically, dopants are incorporated into gel via dissolution of soluble species into the initial precursor sol. In this work, Eu3+ is used as optical probe, to assess changes in the local environment. Results of emission, excitation, fluorescence line narrowing and lifetimes studies of Eu3+-doped gels derived from Si(OCH3)4 and fluorinated/chelate Eu3+ precursors are presented. The precursors used in the sol-gel synthesis were: tris (6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionate) Eu(III), Eu (III) trifluoromethanesulfonate, Eu(III) acetylacetonate hydrate, Eu (III) trifluoroacetate trihidrate, tris (2,2,6,6-tetramethyl-3,5- heptanedionate) Eu(III) and Eu(NO3)3.6H2O. The results were interpreted in terms of the evolution of the Eu3+ fluorescence in systems varying from solution to the gels densified to 800ºC. The lifetimes studies indicate that the fluorinated precursors are effective at reducing the water content in densified gels.

Connectivity in sol-gel silica glasses

In this work it is carried out a review on structural parameters related to the evaluation of pore connectivity of nanostructures. The work describes parameters and methods of evaluation of geometric parameters. The concepts of connectivity are applied to silica gels and glasses obtained from sol-gel process. The study of pores connectivity was carried out using a combination of geometric modeling and experimental evaluation of specific surface area and pore volume. The permeability of the pore structure is evaluated and a permeability geometric factor, Pg, is proposed.

Adsorção do complexo H[Ru(III)Cl2(H2EDTA)] sobre a superfície da sílica gel modificada com [3-(2-aminoetil) aminopropil]trimetoxissilano em soluções etanólicas

Silica gel was functionalized with [3-(2-aminoethyl)aminopropyl]trimethoxysilane group (SF-AEATS) and the characterization by chemical analysis (N) and infrared spectroscopy confirmed the functionalization. The capacity of the modified silica to adsorb the complex Ru(III)-EDTA from ethanolic solution was studied. The selectivity coefficients of the complex formed on the support obtained was (Gñ), 2,07 x 10(4) L/mol and the average number of ligand bonded by one metal ion on the support (ñ) was ~ 1.

Imobilização de 8-hidroxiquinoleína em sílica gel. Melhorias na tradicional rota de diazotação

Some modifications made at silanization step and the introduction of r-nitrobenzil bromide as an alternative reagent to the 8-hydroxiquinolein immobilization in silica gel were important points that brought up the reduction of synthesis time, efficency improvement of the immobilization process and better hydrolysis stabilization to the final materials. The caracterization was made by infrared spectroscopy, elementary analysis, complexing capacity and acid-base properties.

Termoquímica na Unicamp: depoimento sobre uma jornada de 25 anos

This article describes the progress of a group of investigation on thermochemistry, which started in 1972. A homemade calorimeter was employed to provide quantitative support to the information on interative effect between lanthanide cations and halides or pseudohalides, in non-aqueous solvents, previously derived from conductometric titrations. However, the features of this instrument were not able to detect the thermal effects. Therefore, the great input to the group came from the acquisition of an LKB commercial apparatus, by the University in 1975. Considering the historical development of the coordination chemistry in Brazil, which was previously dedicated to strutural features of adducts, without focusing the energetic envolved in any coordinationcompound. Since starting the thermochemistry study, numerous masters and doctoral thesis covering more than a hundred adducts and a reasonable number of chelates, were presented systematizing data in order to understand the behavior of this kind of coordination compounds (C. Airoldi and A. P. Chagas, Coord. Chem. Rev. 1992, 119, 29). This knowledge enabled an extension of the study to include some heterogeneous systems formed by natural or synthetic materials like immobilized silica gel, lamellar phosphate, phosphonate or sulphate compounds, clays, polysaccharides, chrysotile, soils, etc. Many students are now engaged as staff members in Universities, Research Instituitions or other private institutions, developing many activities. Due to a multiplying effect on the formation of researchers, the group is now reaching the fourth generation.

Determinação de Cd, Ni e Zn por espectrometria de emissão atômica com plasma indutivamente acoplado, após separação e pré-concentração em coluna contendo p-dimetilaminobenzilidenorodanina adsorvida sobre sílica gel

A column packed with 5-(4-dimethylaminobenzylidene)rhodanine adsorbed on silica gel was used for the preconcentration of Cd, Ni and Zn at different spiked solutions prior to their determination by inductively coupled plasma atomic emission spectrometry. This column allowed recoveries over than 98% for the above elements and accurate analyses of coastal sea-water certified reference material were also achieved.

Propriedades fotofísicas de Eu3+ e Tb3+ imobilizados em sílica gel funcionalizada com beta-Dicetonas

Synthetic procedures, characterization and luminescent properties of Eu3+ and Tb3+ ions supported on silica gel functionalized with beta-diketones are presented. The functionalization with propyl benzoyltrifluoroacetone (BPG), dibenzoylmethane (DBM) and hexafluoroacetone (HPG), leads to new luminescent materials which photophysical properties depend on the group substituent in the beta-diketone. These systems were evaluated in terms of luminescence and lifetime of the Eu3+ and Tb3+ ions. Silica functionalization was confirmed by TGA and Elemental Analysis. The sample contents of ions were from 0,2 to 0,3 % (w/w).

O uso de sílica gel organofuncionalizada como agente sequestrante para metais

An overview about the homogeneous and heterogeneous methods of synthesizing silylating agents and applications of the organofunctionalized silica-gel samples was explored. The pendant molecules attached covalently to the inorganic surface displayed important properties to act as sequestrating agents for metals in aqueous and non-aqueous solutions. The large variety of basic centres anchored on organic molecules improve the capacity in adsorbing cations. The increase in adsorption is dependent on the number of basic atoms disposed on the pendant molecules on the surface. The combination of acidic and basicity properties favours the selectivity, such is exemplified by the thiol modified silicas towards mercury (II) cations.

Dióxido de titânio sol-gel: propriedades e comportamento eletrocrômico

Titanium dioxide was prepared by hydrolysis and polycondensation of titanium tetraisopropoxide. TiO2 films were obtained by spin coating of the precursor solution on ITO substractes (glass covered with indium doped tin oxide). Films were prepared using different temperatures and hydrochloric acid contents. The effect of the drying temperature of the films (100 or 400ºC) was also investigated. TiO2 films were characterized by cyclic voltammetry, chronoamperometry, ultraviolete-visible spectroscopy, scanning electron microscopy and X-ray diffractrometry.

Studies on formation of chromium niobates

The precise nature of the reaction between chromium chloride and potassium niobate at specific pH levels 12.0, 10.8 and 7.6 has been studied by means of electrometric techniques involving pH and conductometric titrations. The well defined breaks and inflections in the titration curves provide cogent evidence for the formation and precipitation of chromium ortho-Cr2O3.3Nb2 O5, hexa-4Cr2O3.9Nb2 O5 and meta-Cr2O3.3Nb2 O5 niobates in the vicinity of pH 7.5, 6.8 and 5.6, respectively. Analytical investigations of the precipitates have also been carried out which substantiate the results of the electrometric study.

Estudo eletroquímico do azul de metileno adsorvido sobre sílica gel quimicamente modificada com óxido de nióbio

Methylene blue (AM) was immobilised on surface of the silica gel modified with niobium oxide. This material was incorporated in a carbon paste electrode, which showed a redox couple in a potential of E= -113 mV vs SCE in KCl solution at pH 7.0. The formal potential, in 0.5 mol L-1 KCl at pH 7.0, shifted about 290 mV towards more positive values compared to those observed for AM solubilized in aqueous solution. The dependence on the formal potential with solution pH between 2 and 7 was much lower than those observed for AM solubilized in aqueous solution.

Influência da catálise ácida e básica na preparação da sílica funcionalizada pelo método sol-gel

Some aspects of the chemistry involved in the preparation and characterization of functionalized silicon oxide by sol-gel method are considered in this work. The synthesis was performed with different silicon alcoxide precursors and the influence of the acid and basic catalyst was investigated. Characterization was performed by infrared absorption spectroscopy, elemental analysis and 29Si NMR. Infrared data show Si-C and -CH2- vibrational modes at 1250 to 1280 and 2920 to 2940 cm-1, respectively. The elemental analysis confirmed the presence of organic groups in the inorganic silica network. 29Si NMR results show different hydrolisys depending on the acid or base catalysis.