Preparação e propriedades de zeólitas faujasita contendo cátions amônio

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Nanozeólitas como suportes sólidos para imobilização enzimática: Síntese, caracterização de complexos nanozeólitas/enzimas e sua aplicação como catalisadores heterogêneos para produção de biodiesel via rota etílica

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

Synthesis of polycationic bentonite-ionene complexes and their benzene adsorption capacity

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

Lithium intercalation into double rare earth chromates

Lithium intercalation into double rare earth chromates was carried out. It was found that the compounds NaxLi1-xLa(CrO4)2 belong to the NaLa(CrO4)2 structural type and may be recommended as fast ionic conductors. At small values of x a third polymorphous modification of LiLa(CrO4)2 can be stabilized. Attempts to intercalate lithium into CsLa(CrO4)2 lead to collapse of the lamellar network with the formation of LaCrO4 and alkaline chromates. Ion exchange Li+/H+ data are consistent with these considerations. © 1994.

Effect of hexadecyltrimethylammonium bromide-based microemulsions on the rate of decomposition of the beta-lactam antibiotic cephaclor

Microemulsions of hexadecyltrimethylammonium bromide (HTAB)/n-butanol/hexadecane/water catalyze the intramolecular degradation of cephaclor. The rate increase is a sensitive function of the microemulsion volume fraction and salt concentration. The effects of microemulsions, analyzed quantitatively using a pseudophase ion-exchange model, assumed that the extent of ion dissociation from the microemulsions varies with volume fraction. Comparison of micellar and microemulsion effects on the same reaction shows that microemulsions are less effective catalysts. Acceleration decreased significantly by increasing the relative proportion of n-butanol ratio in microemulsions and by addition of n-butanol in HTAB micelles. Comparison of the activation parameters of the reaction in aqueous solution, microemulsions, and micelles suggests that catalysis by both aggregates is driven mainly by entropic contributions.

Overexpression of mitochondrial uncoupling protein 1 (UCP1) induces a hypoxic response in Nicotiana tabacum leaves

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

Estudo comparativo das características bioquímicas funcionais e especificidade catalítica de aspartil, cisteíno e serino peptidases fúngicas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo peptídico e determinação do perfil de metabólitos de venenos de escorpiões da família buthidae: Tityus serrulatus, Tityus bahiensis e Tityus obscurus

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudos experimentais e teórico-computacionais de novos complexos nanozeólitas-enzimas empregados na produção de biocombustíveis

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Phosphorus Availability in an Oxisol Amended with Biosolids in a Long-Term Field Experiment

Many extractors are used to quantify available P in soils, but few studies have assessed the availability of P in soils of the wet tropics amended with high rates of biosolids. In this study, ion exchange resin, Mehlich-1 solution, and Fe-impregnated strips were used to quantify available P in samples from an Oxisol amended with surface-applied biosolids in a long-term field experiment. The soil's maximum capacity for P adsorption was also estimated. Experimental design consisted of randomized blocks, with four treatments and three replicates. Samples of biosolids were collected every year during the experiment, from 1999 to 2002. In 1999, two applications were made before growing maize (Zea mays L.) in austral summer and winter. Treatments were: Control (no biosolids added); B (biosolids added at rates based on their total N content); B2 (biosolids added at twice the rate of B), and B4 (biosolids added at four times the rate of B). Soil samples were collected at 0- to 0.1-, 0.1- to 0.2-, and 0.2- to 0.4-m depths. Biosolids were broadcast applied and incorporated into the soil to a depth of 0.2 m using a rotary hoe. The Oxisol had a high P-adsorption capacity (around 2450 mg kg(-1)) because of its high contents of clay and Fe and Al oxides. All the extractors were effective at assessing P availability and were positively correlated among themselves. Available P soil contents correlated positively with P content in maize leaves and grains, and the resin method yielded the highest correlation with P contents in leaves and grains.

The Chameleon-Like Nature of Zwitterionic Micelles: Effect of Cation Binding

Addition of salts, especially perchlorates, to zwitterionic micelles of SB3-14, C(14)H(29)NMe(2)(+)(CH(2))(3)SO(3)(-), induces anionic character and uptake of H(3)O(+) by SB3-14 micelles. Thus, the addition of alkali metal perchlorates accelerates the acid hydrolysis of 2-(p-heptoxypheny1)-1,3-dioxolane, HPD, in the presence of SB3-14 micelles, which depends on the local proton concentration at the micelle surface. The addition of metal chlorides to solutions of such perchlorate-modified SB3-14 micelles decreases both the negative zeta potential of the micelles and the observed rate constant for acid hydrolysis of HPD. The effect of the monovalent cations Li(+), Na(+), and K(+) is smaller than that of the divalent cations Be(2+), Mg(2+), and Ca(2+), and much smaller than that of the trivalent cations Al(3+), La(3+), and Er(3+). The major factor responsible for this cation valence dependence of these effects is shown to be electrostatic in nature, reflecting the strong dependence of the micellar surface potential on the cation valence. The fact that the salt effects are not identical after correction for the electrostatic effects indicates that additional secondary nonelectrostatic effects may contribute as well.

Batroxase, a new metalloproteinase from B. atrox snake venom with strong fibrinolytic activity

The structures and functional activities of metalloproteinases from snake venoms have been widely studied because of the importance of these molecules in envenomation. Batroxase, which is a metalloproteinase isolated from Bothrops atrox (Para) snake venom, was obtained by gel filtration and anion exchange chromatography. The enzyme is a single protein chain composed of 202 amino acid residues with a molecular mass of 22.9 kDa, as determined by mass spectrometry analysis, showing an isoelectric point of 7.5. The primary sequence analysis indicates that the proteinase contains a zinc ligand motif (HELGHNLGISH) and a sequence C164I165M166 motif that is associated with a "Met-turn" structure. The protein lacks N-glycosylation sites and contains seven half cystine residues, six of which are conserved as pairs to form disulfide bridges. The three-dimensional structure of Batroxase was modeled based on the crystal structure of BmooMP alpha-I from Bothrops moojeni. The model revealed that the zinc binding site has a high structural similarity to the binding site of other metalloproteinases. Batroxase presented weak hemorrhagic activity, with a MHD of 10 mu g, and was able to hydrolyze extracellular matrix components, such as type IV collagen and fibronectin. The toxin cleaves both a and beta-chains of the fibrinogen molecule, and it can be inhibited by EDTA. EGTA and beta-mercaptoethanol. Batroxase was able to dissolve fibrin clots independently of plasminogen activation. These results demonstrate that Batroxase is a zinc-dependent hemorrhagic metalloproteinase with fibrin(ogen)olytic and thrombolytic activity. Published by Elsevier Ltd.

Influence of the use of rice bran extract as a source of nutrients on xylitol production

Xylose-to-xylitol bioconversion using 2.5 or 10% (v/v) rice bran extract was performed to verify the influence of this source of nutrients on Candida guilliermondii metabolism. Semisynthetic medium (SM) and sugarcane bagasse hemicellulosic hydrolysate detoxified with ion-exchange resins (HIE) or with alteration in pH combined with adsorption onto activated charcoal (HAC) were fermented in 125 mL Erlenmeyer flasks at 30 ºC and 200 rpm for 72 hours. Activated charcoal supplemented with 2.5% (v/v) rice bran extract was fermented by C. guilliermondii in a MULTIGEN stirred tank reactor using pH 5.0 and 22.9/hour oxygen transfer volumetric coefficient. Higher values of xylitol productivity (0.70, 0.71, and 0.62 g.Lh-1) and xylose-to-xylitol conversion yield (0.71, 0.69, and 0.63 g.g-1) were obtained with 2.5% (v/v) rice bran in semisynthetic medium, ion-exchange resins, and activated charcoal, respectively. Moreover, during batch fermentation, the xylitol volumetric productivity and fermentation efficiency values obtained were 0.53 g.Lh-1 and 61.1%, respectively.

Metabolismo di oligosaccaridi prebiotici in Bifidobacterium per il potenziale sviluppo di nuovi prodotti alimentari funzionali

The growth and the metabolism of Bifidobacterium adolescentis MB 239 fermenting GOS, lactose, galactose, and glucose were investigated. An unstructerd unsegregated model for growth of B. adolescentis MB 239 in batch cultures was developed and kinetic parameters were calculated with a Matlab algorithm. Galactose was the best carbon source; lactose and GOS led to lower growth rate and cellular yield, but glucose was the poorest carbon source. Lactate, acetate and ethanol yields allowed calculation of the carbon fluxes toward fermentation products. Similar distribution between 3- and 2-carbon products was observed on all the carbohydrates (45 and 55%, respectively), but ethanol production was higher on glucose than on GOS, lactose and galactose, in decreasing order. Based on the stoichiometry of the fructose 6-phosphate shunt and on the carbon distribution among the products, ATP yield was calculated on the different carbohydrates. ATP yield was the highest on galactose, while it was 5, 8, and 25% lower on lactose, GOS, and glucose, respectively. Therefore, a correspondance among ethanol production, low ATP yields, and low biomass production was established demonstrating that carbohydrate preferences may result from different sorting of carbon fluxes through the fermentative pathway. During GOS fermentation, stringent selectivity based on the degree of polymerization was exhibited, since lactose and the trisaccharide were first to be consumed, and a delay was observed until longer oligosaccharides were utilized. Throughout the growth on both lactose and GOS, galactose accumulated in the cultural broth, suggesting that β-(1-4) galactosides can be hydrolysed before they are taken up. The physiology of Bifidobacterium adolescentis MB 239 toward xylooligosaccharides (XOS) was also studied and our attention was focused on an extracellular glycosyl-hydrolase (β-Xylosidase) expressed by a culture of B. adolescentis grown on XOS as sole carbon source. The extracellular enzyme was purified from the the supernatant, which was dialyzed and concentrated by ultrafiltration. A two steps purification protocol was developed: the sample was loaded on a Mono-Q anion exchange chromatography and then, the active fractions were pooled and β-Xylosidase was purified by gel filtration chromatography on a Superdex-75. The enzyme was characterized in many aspects. β- Xylosidase was an homo-tetramer of 160 kDa as native molecular mass; it was a termostable enzyme with an optimum of temperature at 53 °C and an optimum of pH of 6.0. The kinetics parameter were calculated: km = 4.36 mM, Vmax = 0.93 mM/min. The substrate specificity with different di-, oligo- and polysaccharides was tested. The reactions were carried out overnight at pH 7 and at the optimum of temperature and the carbohydrates hydrolysis were analyzed by thin layer chromatography (TLC). Only glycosyl-hydrolase activities on XOS and on xylan were detected, whereas sucrose, lactose, cellobiose, maltose and raffinose were not hydrolyzed. It’s clearly shown that β-Xylosidase activity was higher than the Xylanase one. These studies on the carbohydrate preference of a strain of Bifidobacterium underlined the importance of the affinity between probiotics and prebiotics. On the basis of this concept, together with Barilla G&R f.lli SpA, we studied the possibility to develop a functional food containing a synbiotic. Three probiotic strains Lactobacillus plantarum BAR 10, Streptococcus thermophilus BAR 20, and Bifidobacterium lactis BAR 30 were studied to assess their suitability for utilization in synbiotic products on the basis of antioxidative activity, glutathione production, acid and bile tolerance, carbohydrates fermentation and viability in food matrices. Bile and human gastric juice resistance was tested in vitro to estimate the transit tolerance in the upper gastrointestinal tract. B. lactis and L. plantarum were more acid tolerant than S. thermophilus. All the strains resisted to bile. The growth kinetics on 13 prebiotic carbohydrates were determined. Galactooligosaccharides and fructo-oligosaccharides were successfully utilized by all the strains and could be considered the most appropriate prebiotics to be used in effective synbiotic formulations. The vitality of the three strains inoculated in different food matrices and maintained at room temperature was studied. The best survival of Lactobacillus plantarum BAR 10, Streptococcus thermophilus BAR 20, and Bifidobacterium lactis BAR 30 was found in food chocolate matrices. Then an in vivo clinical trial was carried out for 20 healthy volunteers. The increase in faecal bifidobacteria and lactobacilli populations and the efficacy of the pre-prototype was promising for the future develop of potential commercial products.

Modellierung von Porenraumgeometrien und Transport in korngestützten porösen Medien

Poröse Medien spielen in der Hydrosphäre eine wesentliche Rolle bei der Strömung und beim Transport von Stoffen. In diesem Raum finden komplexe Prozesse statt: Advektion, Kon-vektion, Diffusion, hydromechanische Dispersion, Sorption, Komplexierung, Ionenaustausch und Abbau. Die strömungsmechanischen- und die Transportverhältnisse in porösen Medien werden direkt durch die Geometrie des Porenraumes selbst und durch die Eigenschaften der transportierten (oder strömenden) Medien bestimmt. In der Praxis wird eine Vielzahl von empirischen Modellen verwendet, die die Eigenschaften des porösen Mediums in repräsentativen Elementarvolumen wiedergeben. Die Ermittlung der in empirischen Modellen verwendeten Materialparameter erfolgt über Labor- oder Feldbestimmungsmethoden. Im Rahmen dieser Arbeit wurde das Computer-modell PoreFlow entwickelt, welches die hydraulischen Eigenschaften eines korngestützten porösen Mediums aus der mikroskopischen Modellierung des Fluidflusses und Transportes ableitet. Das poröse Modellmedium wird durch ein dreidimensionales Kugelpackungsmodell, zusam-mengesetzt aus einer beliebigen Kornverteilung, dargestellt. Im Modellporenraum wird die Strömung eines Fluids basierend auf einer stationären Lösung der Navier-Stokes-Gleichung simuliert. Die Ergebnisse der Modellsimulationen an verschiedenen Modellmedien werden mit den Ergebnissen von Säulenversuchen verglichen. Es zeigt sich eine deutliche Abhängigkeit der Strömungs- und Transportparameter von der Porenraumgeometrie sowohl in den Modell-simulationen als auch in den Säulenexperimenten.