Ethanol Production from Sugarcane Bagasse by Zymomonas mobilis Using Simultaneous Saccharification and Fermentation (SSF) Process

Considerable efforts have been made to utilize agricultural and forest residues as biomass feedstock for the production of second-generation bioethanol as an alternative fuel. Fermentation utilizing strains of Zymomonas mobilis and the use of simultaneous saccharification and fermentation (SSF) process has been proposed. Statistical experimental design was used to optimize the conditions of SSF, evaluating solid content, enzymatic load, and cell concentration. The optimum conditions were found to be solid content (30%), enzymatic load (25 filter paper units/g), and cell concentration (4 g/L), resulting in a maximum ethanol concentration of 60 g/L and a volumetric productivity of 1.5 g L^?1?h^?1.     

Bingel-Hirsch reactions on non-IPR Gd3N@C2n (2n = 82 and 84)

The Bingel-Hirsch reactions on non-isolated pentagon rule (non-IPR) Gd(3)N@C(2n) (2n = 82, 84) are studied. Computational results show that the two metallofullerenes display similar reactivity according to their related topologies. Long C-C bonds with large pyramidalization angles lead to the most stable adducts, the [5,6] bonds in the adjacent pentagon pair being especially favored. The lesser regioselectivity observed for Gd(3)N@C(82) is probably due to the activation of some C-C bonds by means of the metal cluster.     

Syntheses and characterization of Cu,Ni and Zn binding capability of histidinehydroxamic acid derivatives

Two histidinehydroxamic acid derivatives (N-methyl-histidinehydroxamic acid, N-Me-Hisha and Z-histidinehydroxamic acid, Z-Hisha) have been synthesized and their complexation with Cu²⁺-, Ni²⁺- and Zn²⁺-ions has been studied by using pH-potentiometric, UV–Vis, CD, ¹H NMR, EPR and ESI-MS methods. Both of the two new derivatives contain one donor atom less compared to the histidinehydroxamic acid (Hisha). In the case of N-Me-Hisha the hydroxamate-N as donor is eliminated, while the coordination of the amino-N of Z-Hisha is not possible at all.     

Prediction of aqueous solubilities of solid carboxylic acids with COSMO-RS

The methodology for the prediction of aqueous solubilities of solid organic compounds, and their temperature dependence, based on the Conductor-like Screening Model for Real Solvents (COSMO-RS/COSMOtherm) procedure, is presented and evaluated. The predictive capability of the quantum chemistry based program and the applied methodology was tested on the most common solid carboxylic acids. From the temperature dependence of the solubilities, the mean apparent enthalpies of solution were derived. The results obtained for a set of 27 carboxylic acids, consisting of aromatic carboxylic acids, dicarboxylic acids, as well as hydroxycarboxylic acids, are in good agreement with the experimental solubility data and their dependence with the temperature. The mean apparent enthalpies of solution, although of the same order of magnitude of the experimentally values, seem to be systematically underestimated.     

Liquid–liquid equilibrium in ternary ionic liquid systems by UNIFAC: New volume,surface area and interaction parameters. Part I

Ternary liquid–liquid equilibria (LLE) data in systems involving ionic liquids has been investigated by several years, mainly due to the innovative role of ionic liquids as extraction solvents. The thermodynamic modeling of these systems has been performed almost invariably with the well-known NRTL model. In recent years, the UNIQUAC model has also been used, with structural parameters for ionic liquids determined either by empirical correlations or, more recently, through quantum mechanics calculations. In this work, the structural group volume and area parameters for the group-contribution UNIFAC method have been calculated for six ionic liquids following the quantum mechanics approach. The Density Functional Theory (DFT) was used to optimize the molecular geometry and the Polarizable Continuum Method (PCM) was used to calculate the area and volume. The obtained parameters were used to correlate LLE data for twenty-four ternary systems, totalizing 169 tie-lines. New interaction parameters were also estimated between the solvent and ionic liquid functional groups. The results are very satisfactory, with root mean square deviations between experimental and calculated compositions about 1.6%.     

Spectrophotometric determination of zinc in copper-base alloys with TAN

TAN reacts with zinc(II) forming a red complex with composition 1:2 Zn(II)-TAN and absorption maximum at 582 nm. Zinc can be determined with this reagent in the presence of Triton X-100, in the pH range 6.20-8.00 with a molar absorptivity of 4.5×10⁴ l/mol/cm Beer's Law was obeyed up to least 1.55 g/ml. Copper interference was eliminated with a mixture of thiosulfate and ascorbic acid and nickel separated by precipitation with dimethylglyoxime. The proposed method was used for zinc determination in several copper-base alloys and the results of analysis in comparison with certified values indicated that the procedure was accurate and precise. A derivative procedure is also proposed, allowing zinc determination with high sensitivity (5-400 ng/ml).     

The inclusion of rhodium(II)α-methyl-cinnamate in β-cyclodextrin

The preparation and characterization of the 1:1 inclusion compound of rhodium(II) -methyl cinnamate in -cyclodextrin is reported. Evidence of inclusion was obtained from X-ray powder diffraction results, Raman, IR and UV-Vis spectroscopic studies and thermal analysis. Given the potential antitumor activity of the rhodium(II) carboxylate and its virtual insolubility in water, its inclusion in -cyclodextrin opens the possibility for its transference to the aqueous phase.     

Host-guest Assembly Based on γ-Cyclodextrin-functionalized Multiwalled Carbon Nanotubes for Rutin Electrochemical Sensing

Here, we report multiwalled carbon nanotubes (MWCNTs) functionalized with γ-cyclodextrins (γCD) as a novel electrochemical strategy for Rutin determination, showing superior performance than β-cyclodextrins (βCD) modified MWCNTs, suggesting an adequate environment for host-guest interactions. Under optimized conditions, the sensor showed a linear range of 39–975 nmol L⁻¹ and a limit of detection of 7 nmol L⁻¹. When tested with quercetin, catechin, and caffeine, the platform presented high selectivity with an interference response <10 %. The method was employed to quantify Rutin in spiked pharmaceutical and herbal extracts, providing recovery of 93–98.4 %. Also, HPLC-PDA confirmed the method‘s accuracy.     

The Biochemical Mechanisms of Antimicrobial Photodynamic Therapy†

The unbridled dissemination of multidrug-resistant pathogens is a major threat to global health and urgently demands novel therapeutic alternatives. Antimicrobial photodynamic therapy (aPDT) has been developed as a promising approach to treat localized infections regardless of drug resistance profile or taxonomy. Even though this technique has been known for more than a century, discussions and speculations regarding the biochemical mechanisms of microbial inactivation have never reached a consensus on what is the primary cause of cell death. Since photochemically generated oxidants promote ubiquitous reactions with various biomolecules, researchers simply assumed that all cellular structures are equally damaged. In this study, biochemical, molecular, biological and advanced microscopy techniques were employed to investigate whether protein, membrane or DNA damage correlates better with dose-dependent microbial inactivation kinetics. We showed that although mild membrane permeabilization and late DNA damage occur, no correlation with inactivation kinetics was found. On the other hand, protein degradation was analyzed by three different methods and showed a dose-dependent trend that matches microbial inactivation kinetics. Our results provide a deeper mechanistic understanding of aPDT that can guide the scientific community toward the development of optimized photosensitizing drugs and also rationally propose synergistic combinations with antimicrobial chemotherapy.