Acylation of a substituted benzofuran over an HY zeolite and its subsequent deacylation and reacylation

The acylation reaction of 2-butylbenzofuran withp-anisoyl chloride andp-anisic acid in the presence of faujasite type zeolites, in the liquid phase, is reported. A good initial selectivity to the 3-acylated derivative is obtained, but the selectivity decreases with time. This result is explained by the involvement of a deacylation-reacylation process.     

Development of the map cracking in concrete under compressive loading

Preliminary to the modeling of the fracture of concrete, it is necessary to make observations at low scale for a better understanding of the phenomena. In this paper, the author shows how to follow the development of the microcracks in a sample during a compressive loading experimentation by the mean of non-destructive takings of replicas observed under S.E.M. The quantification by the stereological method of total projection. Enables to establish a relation between the observed damages and the global behaviour of concrete.     

Antibiotics from the newly isolated Streptomyces elizabethii. I. Production of a polyene antifungal agent (Elizabethin) and actinomycin in shake flask cultures

A new streptomyces strain, designated Streptomyces elizabethii, was isolated from a soil sample using a method which selected antifungal antibiotic producers. S. elizabethii produces an antifungal polyene (elizabethin) and antibacterial actinomycins. Optimal conditions were elucidated for sporulation of the streptomycete in bottle cultures and for polyene production in shake flask cultures. High sugar concentrations were found to repress actinomycin biosynthesis and increase polyene production. Excess potassium phosphate inhibited polyene production.     

Cellulolytic properties of Chaetomium crispatum

The cellulolytic properties of a Chaetomium crispatum strain were investigated. The cellulolytic enzyme complex i.e.: exo-1,4-β-glucosidase (EC 3.2.1.74); endo-1,4-β-glucanase (EC 3.2.1.4.) and β-glucosidase or cellobiase (EC 3.2.1.21) displayed optimal activity at pH 5.0 and 25°C. Although carboxymethyl-celluloses are the usual pseudo-substrates for this enzyme complex, those with a high degree of substitution gave rise to poor growth and low cellulase activity. Insoluble crude cellulosics such as newsprint, recycled paper, rice and flax straw were substantially solubilised at 28°C within 3–5 days of fermentation. A study of the cellulase-complex formation during the growth cycle revealed that β-glucosidase was produced mainly intracellularly in the early exponential phase, while the overall exo-1,4-β-glucosidase and endo-1,4-β-glucanase formation gradually increased during the total fermentation cycle. The mycelial protein of Chaetomium crispatum grown on crude cellulosics displayed a favourable amino acid pattern, indicating its potential value as a source of single cell protein (SCP).     

Trophodynamics of mercury and other trace elements in a pelagic food chain from the Baltic Sea

Mercury (Hg) and 13 other trace elements (Al, Ti, V, Cr, Fe, Mn, Co, Ni, Cu, Zn, As, Cd, and Pb) were measured in phytoplankton, zooplankton, mysis and herring in order to examine the trophodynamics in a well-studied pelagic food chain in the Baltic Sea. The fractionation of nitrogen isotopes (δ¹⁵N) was used to evaluate food web structure and to estimate the extent of trophic biomagnification of the various trace elements. Trophic magnification factors (TMFs) for each trace element were determined from the slope of the regression between trace element concentrations and δ¹⁵N. Calculated TMFs showed fundamental differences in the trophodynamics of the trace elements in the pelagic food chain studied. Concentrations of Al, Fe, Ni, Zn, Pb and Cd showed statistically significant decreases (TMF < 1) with increasing trophic levels and thus these trace elements tropically dilute or biodilute in this Baltic food chain. Cu, As, Cr, Mn, V, Ti and Co showed no significant relationships with trophic levels. Hg was unique among the trace elements studied in demonstrating a statistically significant increase (TMF > 1) in concentration with trophic level i.e. Hg biomagnifies in this Baltic food chain. The estimated TMF for Hg in this food chain was comparable to TMFs observed elsewhere for diverse food chains and locations.     

Evolution of aroma compounds of murtilla fruits (Ugni molinae Turcz) during storage

BACKGROUND: ‘Murtilla’, ‘mutilla’ or ‘murta’ (Ugni molinae Turcz) is a native Chilean species that produces a small berry fruit with a special aroma, whose volatile compounds have not yet been identified. The fruit may be consumed raw and also as jams, juice, canned products, confections and liquor. RESULTS: At the beginning and end of the storage, 24 volatile compounds were identified in murtilla fruit aroma and the concentration of these compounds in murtilla fruit ranged from 1.2 to 250.5 µg kg^?1 fresh weight. Methyl 2‐methyl butanoate, ethyl butanoate, ethyl 2‐methyl butanoate, methyl hexanoate, ethyl hexanoate, methyl benzoate and ethyl benzoate were the major components, all of which have been reported as potent odors in other aromatic fruits. Based on estimated odor activity value, the most potent compound in the murtilla fruit aroma were ethyl hexanoate and 4‐methoxy‐2,5‐dimethyl‐furan‐3‐one. The statistical analysis showed that the storage produced a distinct effect on the same volatile compounds released from the murtilla ecotypes. CONCLUSION: The volatile compounds identified in murtilla fruit aroma, which may be described as fruity, sweet and floral, have been found in other aromatic fruits. Concerning the aroma, the murtilla fruit from ecotype 19‐1 was shown to be the best in cooled storage. Copyright © 2007 Society of Chemical Industry     

Effect of geometry and hybrid adhesive on strength of finger joints of Pinus elliottii subject to humidity and temperature

The optimized bonding of glued finger joints is required for structural and nonstructural applications. The use of nonspecific adhesives, combined with the joint geometry and exposure of joints to humidity and temperature, are factors that can compromise the durability of glued joints. The main objective of this study is the development of cross-linking poly(vinyl acetate) (PVAc) hybrid adhesive to produce nonstructural finger joints of Pinus elliottii with finger lengths of 6.5 and 4.5 mm. The adhesives were produced by emulsion copolymerization of vinyl acetate with n-butyl acrylate with different amounts of N-methylol acrylamide and blended with resorcinol-formaldehyde resin (RF) and aluminum chloride (AlCl₃). The rheological behavior of adhesives was investigated. We found that the joint configuration and the exposition time employed influenced joint strength. The PVAc/RF adhesive showed a thicker bond line and consequent deeper penetration into the pores of the wood as verified by microscopy analysis. Statistically differences in bond strength of the adhesive joints were found with respect to different conditioning times and finger length. The highest values were exhibited by the joints produced with a finger length of 6.5 mm and glued with the hybrid adhesive (AD-4) than that joints produced with a finger length of 4.5 mm.     

A gelatin/PLA-b-PEG film of excellent gas barrier and mechanical properties

A polylactic acid-polyethylene glycol block copolymer (PLA-b-PEG) was used as an additive to prepare gelatin/PLA-b-PEG blend films for the first time. The PEG molecule block enhanced the compatibility of the PLA molecule block with gelatin, which greatly improved the excellent mechanical and gas barrier properties of the gelatin film. The film contained 5 wt% PLA-b-PEG possessed the highest tensile strength and the highest elastic modulus. When the PLA-b-PEG content further increased to 20 wt%, the tensile strength, elastic modulus and elongation at the break of the blend film were all higher than pure gelatin film, suggesting that the gelatin/PLA-b-PEG blend film was pliable and tough. The blend film possessed not only excellent oxygen barrier property, but also a much-improved water barrier property. The degradation rate of the blend film was elongated controllably by regulating the content of the PLA-b-PEG copolymer. The blend film showed great potential in the application of food packaging.     

Benzimidazole Derivatives as New and Selective Inhibitors of Arginase from Leishmania mexicana with Biological Activity against Promastigotes and Amastigotes

Leishmaniasis is a disease caused by parasites of the Leishmania genus that affects 98 countries worldwide, 2 million of new cases occur each year and more than 350 million people are at risk. The use of the actual treatments is limited due to toxicity concerns and the apparition of resistance strains. Therefore, there is an urgent necessity to find new drugs for the treatment of this disease. In this context, enzymes from the polyamine biosynthesis pathway, such as arginase, have been considered a good target. In the present work, a chemical library of benzimidazole derivatives was studied performing computational, enzyme kinetics, biological activity, and cytotoxic effect characterization, as well as in silico ADME-Tox predictions, to find new inhibitors for arginase from Leishmania mexicana (LmARG). The results show that the two most potent inhibitors (compounds 1 and 2) have an I₅₀ values of 52 μM and 82 μM, respectively. Moreover, assays with human arginase 1 (HsARG) show that both compounds are selective for LmARG. According to molecular dynamics simulation studies these inhibitors interact with important residues for enzyme catalysis. Biological activity assays demonstrate that both compounds have activity against promastigote and amastigote, and low cytotoxic effect in murine macrophages. Finally, in silico prediction of their ADME-Tox properties suggest that these inhibitors support the characteristics to be considered drug candidates. Altogether, the results reported in our study suggest that the benzimidazole derivatives are an excellent starting point for design new drugs against leishmanisis.