Viability of Using Glycerin as a Co-substrate in Anaerobic Digestion of Sugarcane Stillage (Vinasse): Effect of Diversified Operational Strategies

Vinasse, from sugar and ethanol production, stands out as one of the most problematic agroindustry wastes due to its high chemical oxygen demand, large production volume, and recalcitrant compounds. Therefore, the viability of using glycerin as a co-substrate in vinasse anaerobic digestion was tested, to increase process efficiency and biogas productivity. The effect of feeding strategy, influent concentration, cycle length, and temperature were assessed to optimize methane production. Glycerin (1.53% v/v) proved to be a good co-substrate since it increased the overall methane production in co-digestion assays. CH₄ productivity enhanced exponentially as influent concentration increased, but when temperature was increased to 35 °C, biogas production was impaired. The highest methane productivity and yield were achieved using fed-batch mode, at 30 °C and at an organic loading rate of 10.1 kg COD m⁻³ day⁻¹: 139.32 mol CH₄ m⁻³ day⁻¹, 13.86 mol CH₄ kg COD_applied, and 15.30 mol CH₄ kg COD_removed. Methane was predominantly produced through the hydrogenotrophic route. In order to treat all the vinasse produced by a mid-size sugar and ethanol plant, nine reactors with 7263.4 m³ each would be needed. The energy generated by burning the biogas in boilers would reach approximately 92,000 MW h per season and could save up to US$ 240,000.00 per month in diesel oil demand.

     

Performance of anaerobic sequencing batch biofilm reactor submitted to different influent volume feeds and cycle time periods maintaining organic loading

The stability and efficiency of an anaerobic reactor containing biomass immobilized on polyurethane foam were assessed. The reactor with mechanical stirring of 500 rpm and maintained at 30+/-1 degrees C treated synthetic wastewater with a concentration of approx 500 mg of chemical oxygen demand/L and was fed with different influent volumes and cycle times maintaining organic load. Operation was in batch mode with renewal of only part of the volume of wastewater to be treated; that is reactor discharge was not complete, but partial. The main operational characteristic investigated was the ratio of the volume of wastewater fed per cycle (VA) to the volume of wastewater in the reactor (VA) maintaining the same volumetric organic load. This way, operating flexibility could be verified in relation to the volume of treated wastewater at each cycle and the cycle time for the same organic load. The results indicated that the reactor was able to operate with different VA/Vu ratios with no significant loss in performance, thus allowing increased operational flexibility. For conditions in which VA was >or=50% of VA, removal efficiencies of filtered and nonfiltered organic matter were about 84 and 79%, respectively, whereas at conditions of higher initial influent dilution, these efficiencies were slightly lower, about 80 and 74%, respectively. At higher initial influent dilutions, it became difficult to maintain a constant reactor medium volume, owing to a high formation rate of viscous polymer-like material, likely of microbiologic origin.     

A multiscale wavelet data treatment for reliable localization of inflection points for analytical purposes

Instrumental analysis techniques that employ measurements based on inflection points may have their accuracy compromised due to the need for signal differentiation, which is very sensitive to instrumental noise. This paper presents a strategy for localizing inflection points that exploits the multiscale processing capability of the Wavelet Transform and avoids the need for explicit signal differentiation. The strategy is illustrated in simulated examples and also in a real analytical problem involving the determination of Pb and Cd by potentiometric stripping analysis. In this application, the results were in good agreement with the expected values and were slightly better than those obtained from the first derivative of the curves after smoothing by a Windowed Fourier Transform.     

Selective incorporation of isotopically labeled amino acids for identification of intact proteins on a proteome-wide level

The post-genomic era and increased demands for broad proteome measurements have greatly increased the needs for protein identification. We describe a strategy that uses accurate mass measurements and partial amino acid content information to unambiguously identify intact proteins, and show its initial application to the proteomes of Escherichia coli and Saccharomyces cerevisiae. Proteins were extracted from the organisms grown in minimal medium or minimal medium to which isotopically labeled leucine (Leu-D(10)) had been added. The two protein extracts were mixed and analyzed by capillary isoelectric focusing (CIEF) coupled with Fourier transform ion cyclotron resonance mass spectrometry (FTICR). The incorporation of the isotopically labeled residue has no effect on the CIEF separation of proteins, and both isotopically labeled and unlabeled versions of specific proteins are observed within the same mass spectrum. The difference in the mass of the unlabeled and labeled proteins is used to determine the number of Leu residues present in a particular protein. Proteins can then often be unambiguously identified based on their accurately determined molecular mass and the additional constraint provided by number of Leu residues. The identities of proteins were further confirmed by repeating CIEF/FTICR measurements with samples that contain other isotopically labeled amino acid residues (e.g. His, Arg, Ile, Phe, Lys). A theoretical study of the amino acid composition (for a difference in the amino acid sequence) showed the constraints needed in order to identify the protein unambiguously. Additionally, the mass differences between the predicted and the experimental accurate mass measurement provide insights into the nature of simple post-translational modifications.     

Modification of proton conductive polymer membranes with phosphonated polysilsesquioxanes

New hybrid membranes for fuel cell applications based on sulfonated poly(ether ether ketone) (SPEEK) and phosphonated polysilsesquioxanes were synthesized. The impedance spectroscopy measurements show an increase of the proton conductivity for all studied composites, in comparison to plain SPEEK. For hybrid membranes containing 20 wt% of polysilsesquioxane with 80 mol% of phosphonated units the conductivities can reach values that are similar to Nafion 117^® at 100% RH. The best results of proton conductivity (142 mS/cm) were obtained for composites with 40 wt% of the same polysilsesquioxane at 120 °C also at 100% RH.     

Antinociceptive profile of 2,3,6-trisubstituted piperidine alkaloids: 3-O-acetyl-spectaline and semi-synthetic derivatives of (-)-spectaline

In early studies, we have reported the antinociceptive profile of (-)-spectaline, a piperidine alkaloid from Cassia spectabilis. The present study describes the synthesis, the antinociceptive and anti-inflammatory activities of a series of 2,3,6-trialkyl-piperidine alkaloids: the natural (-)-3-O-acetyl-spectaline (LASSBio-755) and ten semi-synthetic spectaline derivatives. Structure-activity relationship (SARs) studies were performed. The structures of all synthesized derivatives were confirmed by means of nuclear magnetic resonance. Compounds were evaluated for their analgesic (acetic acid-induced mouse abdominal constrictions, hot-plate test, formalin-induced pain test) and some of them for the anti-inflammatory activities (carrageenan-induced rat paw edema test). The pharmacological results showed that several of the new compounds given orally at a dose of 100 micromol/kg significantly inhibited the acetic acid-induced abdominal constrictions, but they were less active than (-)-spectaline. LASSBio-755 and LASSBio-776 were the most actives with 37% and 31.7% of inhibition. In the formalin-induced pain only LASSBio-776 was able to inhibit by 34.4% the paw licking response of the inflammatory phase, (-)-spectaline and LASSBio-755 did show any activity. In the carrageenan-induced rat paw edema, only (-)-spectaline exhibited an anti-inflammatory profile, showing an ED(50) value of 56.6 micromol/kg. Our results suggest different mechanisms of action for the analgesic activity observed for LASSBio-776 (3-O-Boc-spectaline), LASSBio-755 (3-O-acetyl-spectaline) and (-)-spectaline (LASSBio-754). The antinociceptive profile of some of the semi-synthetic spectaline derivatives extends our research concerning the chemical and pharmacological optimization of isolated natural products in the search of new drug candidates from Brazilian biodiversity.     

Antibacterial effect of silver nanoparticles deposited on corona‐treated polyester and polyamide fabrics

The possibility of using a corona treatment (electrical discharge at atmospheric pressure) for fiber surface activation, which can facilitate the loading of silver nanoparticles (NPs) from colloids onto the polyester (PES) and polyamide (PA) fabrics and thus improve their antibacterial properties, was studied. Bactericidal efficiency and its laundering durability on silver‐loaded fabrics for Gram‐positive bacterium Staphylococcus aureus and Gram‐negative bacterium Escherichia coli were evaluated. The fiber morphology after corona treatment and subsequent loading of silver NPs was followed by SEM. Corona‐treated fabrics loaded with silver NPs exhibited better antibacterial properties in comparison with untreated fabrics. In order to obtain acceptable laundering durability, it is necessary to use highly concentrated silver colloids. Copyright © 2008 John Wiley & Sons, Ltd.     

The influence of the nanofiller on thermal properties of thermoplastic polyurethane elastomers

Pure Fe₃O₄ and Mn-doped Fe₃O₄ nanoparticles were synthesized by simple wet chemical reduction technique using nontoxic precursors. Manganese doping of two concentrations, 10 and 15%, were employed. All the three synthesized nanoparticles were characterized by stoichiometry, crystal structure, and surface morphology. Thermal studies on as-synthesized nanoparticles of pure ferrite (Fe₃O₄) and manganese (Mn) doped ferrites were carried out. The thermal analysis of the three as-synthesized nanoparticles was done by thermogravimetric (TG), differential thermogravimetric, and differential thermal analysis techniques. All the thermal analyses were done in nitrogen atmosphere in the temperature range of 308–1233 K. All the thermocurves were recorded for three heating rates of 10, 15, and 20 K min^?1. The TG curves showed three steps thermal decomposition for Fe₃O₄ and two steps thermal decompositions for Mn-doped Fe₃O₄ nanoparticles. The kinetic parameters of the three as-synthesized nanoparticles were evaluated from the thermocurves employing Kissinger–Akahira–Sunose (KAS) method. The thermocurves and evaluated kinetic parameters are discussed in this paper.