Screening of microorganisms for bioconversion of (−)β-pinene and R-(+)-limonene to α-terpineol

This work is focused on the bioconversion of (−)β-pinene and R-(+)-limonene to α-terpineol. To carry out the present study, 400 microorganisms were tested for their ability to bioconvert the substrates. From the microorganisms, no one was able to convert R-(+)-limonene and 4 were able to bioconvert (−)-β-pinene to oxygenated monoterpenes. The metabolites recovered were α-terpineol (2856.54 ± 50.23 mg/L) and fenchol (traces) for Aspergillus niger ATCC 16404, α-terpineol (688.13 ± 41.27 mg/L) for A. niger ATCC 9642, α-terpineol (172.07 ± 32.94 mg/L) for A. niger ATCC 1004 and α-terpineol (24.38 ± 2.78 mg/L) and trans-pinocarveol (traces) for Penicillium camembertii ATCC 4845. After screening and optimization experiments, the best experimental condition for bioconversion of (−)β-pinene to α-terpineol was established using A. niger ATCC 16404 at 35 °C without addition of vitamin solution, yielding a conversion in α-terpineol of 15494.34 ± 193.87 mg/L.     

Quantitative GC-ECD Analysis of Halogenated Metabolites: Determination of Surface and Within-Thallus Elatol of Laurencia obtusa

Information on natural concentrations or variability of secondary metabolites in marine organisms may be important both to ecological/evolutionary and applied approaches. A gas chromatographic procedure with an electron capture detector (GC-ECD) was developed to quantify the sesquiterpenoid elatol at the surface and within-thalli of 70 specimens of the red seaweed Laurencia obtusa. The concentration of elatol was highest within-thalli [9.89 mg g⁻¹ of L. obtusa, dry weight (d.w.)], compared to lower values found at the surface [0.006 mg g⁻¹ of L.obtusa (d.w.), or 0.5–10.0 ng cm⁻²]. This method provides a rapid and inexpensive quantification of small quantities of elatol, and probably may also be used to quantify other halogenated compounds usually found in red seaweeds.     

Colloidal Co nanoparticles supported on SiO2: Synthesis, characterization and catalytic properties for steam reforming of ethanol

Colloidal Co nanoparticles with sizes in the 3–8 nm range were obtained by thermal decomposition of Co₂(CO)₈ in the presence of ligands and impregnated on SiO₂ to prepare SiO₂-supported Co nanocatalysts. The catalysts showed activity for the steam reforming of ethanol with higher values for smaller Co particles. H₂ adsorption results and Fourier transform infrared spectroscopy of adsorbed CO suggested that the fraction of accessible Co sites also depended on the synthesis conditions. Precipitation of the Co nanoparticles with methanol instead of ethanol before impregnation had a positive effect on the density of accessible Co sites to catalysis; similar result was verified by increasing the thermal treatment temperature under H₂ flow before the reaction. Based on the distribution of products with temperature of reaction, a mechanism for steam reforming of ethanol on SiO₂-supported Co nanocatalysts is suggested.     

Tribocorrosion and corrosion behavior of stainless steel coated with DLC films in ethanol with different concentrations of water

There has been a recent increase in both the production and consumption of ethanol due to the numerous environmental advantages that it offers, such as the fact that it can be produced from a variety of renewable materials, for instance corn and cellulose, or it can be obtained from sugarcane bagasse and biomass (2nd and 3rd generation ethanol). The result of this is that nowadays ethanol is widely seen as the dominant biofuel – or as a blend component in gasoline or pure fuel - in many countries.However, one disadvantage of the use of ethanol is the high corrosive behavior that occurs when its hygroscopic properties are exposed to a large number of materials. Xiaoyuan Lou and Preet Singh showed that the increase of water concentration in ethanol induces pitting and metal loss. Diamond-Like Carbon (DLC) films may be a solution to this problem due to the fact that they can be deposited inside tubes, offer good protection levels against corrosion, and reduce the friction coefficient and wear.This paper shows the tribocorrosion and corrosion studies of DLC films deposited on stainless steel grade 304 (SS304) substrates in order to gauge its appropriateness usage in the construction of pipelines and fuel storage tanks. The surface morphology was analyzed before and after 14 days of immersion. The tribocorrosion, friction coefficient, and wear rate were studied in ethanol to see the effects of water concentration. The films showed good adherence to the substrates. Corrosion and tribocorrosion results showed that for bare Stainless Steel 304 the increase of the water content increases the corrosion and the friction coefficient. DLC coated samples presented few points of delamination, and the friction coefficient and open circuit potentials were very low compared with the bare sample which was water concentration independent.     

Influence of ultimate pH on biochemistry and quality of Longissimus lumborum steaks from Nellore bulls during ageing

Ultimate pH (pH_u) is an indicator that influences post-mortem meat quality. We studied physiological and biochemical changes of steaks obtained from Nellore bulls (Bos indicus) during post-mortem ageing. To this, Longissimus lumborum (LL) muscles were classified into three groups: Normal-pH_u (≤5.79), Intermediate-pH_u (5.80–6.29) and High-pH_u (≥6.30) groups, portioned into steaks, vacuum packaged and matured at 2 °C for 0, 7, 14, 21 and 28 days. High-pH_u steaks exhibited impaired colour stability and were darker compared to the other groups. High- and Normal-pH_u steaks showed improved tenderness and myofibrillar fragmentation linked to proteolysis. Intermediate-pH_u steaks were associated with a lower meat tenderness and decreased collagen solubility. High-pH_u steaks retained a high pH during ageing and increased water-holding capacity. These findings provide evidence that highlight pH_u as a strategy for the classification of pH_u-dependent beef quality from Nellore bulls that can be adopted by the Brazilian meat industry.     

A block-symmetric linearization of odd degree matrix polynomials with optimal eigenvalue condition number and backward error

The standard way of solving numerically a polynomial eigenvalue problem (PEP) is to use a linearization and solve the corresponding generalized eigenvalue problem (GEP). In addition, if the PEP possesses one of the structures arising very often in applications, then the use of a linearization that preserves such structure combined with a structured algorithm for the GEP presents considerable numerical advantages. Block-symmetric linearizations have proven to be very useful for constructing structured linearizations of structured matrix polynomials. In this scenario, we analyze the eigenvalue condition numbers and backward errors of approximated eigenpairs of a block symmetric linearization that was introduced by Fiedler (Linear Algebra Appl 372:325–331, 2003) for scalar polynomials and generalized to matrix polynomials by Antoniou and Vologiannidis (Electron J Linear Algebra 11:78–87, 2004). This analysis reveals that such linearization has much better numerical properties than any other block-symmetric linearization analyzed so far in the literature, including those in the well known vector space \(\mathbb {DL}(P)\) of block-symmetric linearizations. The main drawback of the analyzed linearization is that it can be constructed only for matrix polynomials of odd degree, but we believe that it will be possible to extend its use to even degree polynomials via some strategies in the near future.     

Electroflocculation for the treatment of wastewater from dairy food industry: scale-up of a laboratory reactor to full-scale plant

Clean Technologies and Environmental Policy - The aim of this work was to evaluate the scale-up of a laboratory reactor to full-scale plant for the electroflocculation of dairy food industry...     

Chitin derived biochar as an alternative adsorbent to treat colored effluents containing methyl violet dye

Chitin was used to prepare an alternative, eco–friendly and low–cost adsorbent by a simple pyrolysis process. The adsorbent, named chitin derived biochar, was characterized and applied to treat colored effluents containing methyl violet dye (MV). Pyrolysis using N₂ flow rate of 0.25 L min^?1, heating rate of 10 °C min^?1 until 800 °C was suitable to prepare a chitin derived biochar with good characteristics. Chitin derived biochar presented surface area of 275.0 m² g^?1. The MV adsorption on the chitin derived biochar was favored in alkaline conditions and ambient temperature. The adsorption process presented fast kinetics and, the maximum adsorption capacity was higher than 1000 mg g^?1. Chitin derived biochar can be used for 7 consecutive adsorption/desorption cycles maintaining the same adsorption capacity. Also, the material was suitable to treat colored effluents, reaching color removal percentage of 95%. In brief, it was demonstrated that chitin derived biochar is a low–cost and efficient material to treat colored effluents.     

The greatest co-authorships of finance theory literature (1896–2006): scientometrics based on complex networks

Scientometrics - We use some modern scientometrics tools to detect which articles written in co-authorship are the most influential in the finance theory literature from 1896 to 2006. To develop a...