Immobilized microorganisms in the reduction of ethyl benzoylacetate

The enantioselective reduction of ethyl benzoylacetate (EBA) into ethyl (S)-3-hydroxy-3-phenylpropanoate (S-HPPE) by nine yeast strains and three filamentous fungi strains is described. The conversion obtained was in the range 0-89% and the enantiomeric excess was 100% in many cases. Conversion levels were higher when the reduction was performed with microorganisms immobilized in calcium alginate and enantioselectivity remained excellent. Some reaction’s conditions of bioreduction by immobilized cells of Rhodotorula rubra were studied using a 2^5-2 fractional factorial design.     

A New Extraction and Purification Methodology of Bowman-Birk Inhibitors from Seeds and Germinated Seeds of Macrotyloma axillare

The Macrotyloma axillare Bowman-Birk inhibitors from seeds and germinated seeds (120 h) were purified by an alternative methodology and revealed the presence of different contents of inhibitors for each treatment. Mass analyses of inhibitors, from seeds and germinated seeds, showed masses of about 7 and 8 kDa. The 120 h-germinated seed fractions presented higher activity isoforms than seeds without treatment.

     

Simultaneous determination of aluminoxamine and ferrioxamine in post-hemodialysis fluids by spectrophotometry and multivariate calibration

A spectrophotometric method for simultaneous determination of Al(III) and Fe(III) using the chelator Desferal® (desferrioxamine B) was developed. Partial least squares (PLS) regression was performed to resolve the overlapped signals obtained from Al(III) and Fe(III) complexes. The parameters controlling behavior of the system were investigated and optimum conditions were selected. PLS was the choice for the analysis of binary mixtures of Fe(III) and Al(III) over the range of 0.1 to 0.8 mg L^?1 by using the data of first derivative spectra. Absorbance data were taken between 200 and 600 nm. The calculated sensitivity values for the multivariate method were 4.88 and 5.64 for Al(III) and Fe(III), respectively. Multivariate detection limits were 0.075 and 0.064 mg L^?1 for Al(III) and Fe(III), respectively. The method was applied to real post-hemodialysis samples, and sample digestion by UV irradiation was discussed.     

Tin(IV) derivatives of 2,6-pyridinedicarboxylate: A Sn Mössbauer spectroscopic investigation

A series of organotin(IV) derivatives of 2,6-pyridinedicarboxylate has been investigated by Mössbauer spectroscopy in order to elucidate aspects concerning bonding and structural features in the solid state. A geometrical pattern of five-fold coordination at the metal centre has been revealed for SnCl₃Bu and SnClBu₃ derivatives. Trans stereochemistry for the butyl and vinyl groups of SnCl₂Bu₂ and SnCl₂(Vin)₂ derivatives has also been identified by this method. The isomer shift for the divinyl derivative is concurrent to a 7-coordinate metal centre contrasting to that for the dibutyl one. Although there is a discrepancy in isomer shift between these compounds, both have seven-fold coordination at the Sn(IV) nucleus. The resulting data has given evidence that 2,6-pyridinedicarboxylate is acting as a tridentate ligand through pyridil and carbolxylate moiety to all derivatives except for SnClBu₃. For the latter, the coordination mode occurs via carboxylate groups. The overall data support distorted geometrical pattern to all complexes in solid state.     

Fast heuristics for the Steiner tree problem with revenues,budget and hop constraints

This article describes and compares three heuristics for a variant of the Steiner tree problem with revenues, which includes budget and hop constraints. First, a greedy method which obtains good approximations in short computational times is proposed. This initial solution is then improved by means of a destroy-and-repair method or a tabu search algorithm. Computational results compare the three methods in terms of accuracy and speed.     

Limewashing paintings in Alentejo urban heritage: pigment characterization and differentiation by WDXRF and XRD

Pigments used in traditional limewashing paintings in Alentejo urban Heritage are inorganic materials and can be grouped into four categories: a) reds – red ochre (from terras rossas, red schists and iron ore deposits weathering), almagres, terra roxa (natural processed red ochres) and synthetic red iron oxides; b) yellows – yellow ochre (from schists and iron ore deposits), processed natural ochres, yellow iron synthetic oxides, c) blacks – black earths and black iron synthetic oxides and d) blues – artificial ultramarine. The present work proposes to characterize natural, natural processed and synthetic pigments by comparing phase and elemental compositions. The results reveal differences in Fe, Si, K and Al total content according to their origin and fabrication process and reveal intentional addition of white charges like carbonates. Elements like Zr, Ti, Cr, Mn, Ca and Zn are present in all categories. Under optical microscopy, some samples of processed natural pigments do not exhibit optical activity, thus revealing mixtures with synthetic pigments, while natural pigments present a strong birefringence colorless due to optically active minerals. PACS 78.70.En; 07.60.Pb; 61.10.Nz; 81.70.-q; 91.60.-x     

Photoinduced,Direct C(sp2)−H Bond Azo Coupling of Imidazoheteroarenes and Imidazoanilines with Aryl Diazonium Salts Catalyzed by Eosin Y

Herein, a greener approach to the eosin Y-Na₂ catalyzed, C(sp²)−H bond azo coupling of imidazoheteroarene with aryl diazonium salts is described, under acid free conditions. This direct photoredox process resulted in the corresponding azo products in good to excellent yields. Besides, this new approach could also be applicable to anilines, which is a poorly reactive substrate by other methods. The main features of this reaction are that it provides high yields and is gram-scalable and applicable to biologically relevant imidazoheteroarenes and -anilines.     

Highly sensitive photoelectrochemical immunosensor based on anatase/rutile TiO2 and Bi2S3 for the zero-biased detection of PSA

Journal of Solid State Electrochemistry - A novel label-free photoelectrochemical immunosensor was developed for the determination of prostate-specific antigen (PSA) based on fluorine-doped tin...