Chemical and microbiological quality of sugar cane juice influences the concentration of ethyl carbamate and volatile congeners in cachaça

The aim of this study was to assess the influence of heat treatment of sugar cane juice, supplementation with urea and double distillation on the concentration of volatile congeners (acetic aldehyde, ethyl acetate, n‐propyl, isobutyl and isoamyl alcohols and acetic acid) and contaminants (methanol, 1‐propyl and 2‐butyl alcohols, copper, and ethyl carbamate) in cachaça. Samples of fresh sugar cane juice, sugar cane juice submitted to heat treatment and contaminated sugar cane juice were supplemented (or not) with urea and fermented. The washes so obtained underwent single and double distillation. Supplementation with urea stimulated ethyl carbamate formation. The distilled products that originated from contaminated worts presented higher concentration of acetic acid and ethyl carbamate. Double distillation reduced the concentration of contaminants. The best quality pot still cachaça was obtained employing heat treatment of sugar cane juice, nonsupplementation with urea and double distillation. Copyright © 2015 The Institute of Brewing & Distilling     

Inoculum acclimation to oleate promotes the conversion of olive mill wastewater to methane

This work aims at selecting a suitable strategy to accelerate the start-up of the anaerobic treatment of olive mill wastewater (OMW) and to enhance the biogas production. Two anaerobic sludges were tested in toxicity and biodegradability batch experiments: biomass acclimated to oleate (BAO) and biomass non-acclimated (BNA). The results showed that the resistance to OMW toxicity was higher for the BAO than for the BNA. In the presence of OMW, the BNA was inhibited at all concentrations tested, whereas for the BAO no inhibition occurred at 5 and 10 g COD L⁻¹. In fact, even at 25 g COD L⁻¹ both substrates (acetate + OMW) were degraded. The biodegradation rate of OMW was higher in batch vials with the acclimated sludge.The results demonstrate that the use of an acclimated microbial consortium to LCFA compounds is a promising strategy to accelerate the start-up of the digestion process, and to improve the overall anaerobic treatment of a real oily wastewater such as OMW with simultaneous bioenergy production (biogas).     

The comparison of the corrosion resistance of advanced ferromagnetic stainless steels by Mott–Schottky approach

Ferromagnetic stainless steels (SSs) have been investigated as potential candidates for dental prosthesis applications in replacement of magnetic attachments made of noble and expensive alloys. In order to be used as biomaterials, their corrosion resistance has to be appropriate. The corrosion resistance of passive materials is related to the characteristics of the passive film formed and their properties might be investigated by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization curves, and Mott–Schottky approach. The corrosion resistance and the capacitance of the passive films formed on PM2000, DIN 1.4575, and 17‐4 PH advanced SSs during 2 days of immersion in a phosphate buffered saline solution (PBS), at 25 °C and pH 7.0 were studied by electrochemical techniques. A commercial alloy Dyna EFM was also analyzed for comparison reasons. The results showed that films on tested materials behave as both n‐type and p‐type semiconductors and the PM2000 presented the highest corrosion resistance among all of them.     

Easy mass spectrometry for metabolomics and quality control of vegetable and animal fats

Easy ambient sonic spray ionization (EASI), a novel desorption/ionization technique for ambient mass spectrometry analysis, is shown to permit the characterization of different types of vegetable and animal fats. The taxonomic markers of the oils, mainly fatty acids and phenols, are extracted with methanol/water (1:1) solution and made alkaline with NH₄OH, then placed and dried on the surface of a glass tip and directly analyzed by EASI‐MS in the negative‐ion mode. EASI provides a supersonic cloud of charged droplets that causes efficient desorption and ionization of the oil markers directly from the surface of the glass tip. As proof‐of‐principle cases, EASI(?)‐MS was applied to genuine samples of olive oil, hazelnut oil, soybean oil, grape seed oil, canola oil, butter, and lard. Characteristic metabolomics EASI(?)‐MS profiles of fatty acids and eventually phenols were obtained.     

Gap inner pressures in multi-storey double skin facades

Double-skin façades (DSF) are used as an architectural solution to improve indoor comfort being characterized by having at least two membranes between the interior occupied space and the exterior environment, separated by an air gap where the shading devices lie. The pressure within the gap plays an important role on (i) the glazing structural safety; (ii) the shaft ventilation, in particular if a natural ventilation scheme is implemented, but also to promote an efficient gap air change, and (iii) the safety of maintenance staff, especially when windows may be opened to the interior. Although there are several DSF typologies only the multi-storey case, where no horizontal or vertical partitioning exists between the two skins, will be analysed in this paper. Nevertheless, there are still a number of possible layouts for multi-storey DSF that might impose different pressure distributions within the gap. This paper refers to a set of wind tunnel tests made over a building model with different multi-storey DSF layouts—from open on all edges to fully lateral closure and from narrow to wide gap depths, for an extended range of wind directions. The experimental data showed a layout dependent inner wall pressure distribution that may be considerably different from the unsheltered building.     

(Virtual) Agents for running electricity markets

This paper describes a multi-agent based simulation (MABS) framework to construct an artificial electric power market populated with learning agents. The artificial market, named TEMMAS (The Electricity Market Multi-Agent Simulator), explores the integration of two design constructs: (i) the specification of the environmental physical market properties and (ii) the specification of the decision-making (deliberative) and reactive agents. TEMMAS is materialized in an experimental setup involving distinct power generator companies that operate in the market and search for the trading strategies that best exploit their generating units’ resources. The experimental results show a coherent market behavior that emerges from the overall simulated environment.     

Long-term stability of hydrogen and organic acids production in an anaerobic fluidized-bed reactor using heat treated anaerobic sludge inoculum

This study evaluates the stability of hydrogen and organic acids production in an anaerobic fluidized-bed reactor (AFBR) that contains expanded clay (2.8–3.35 mm in diameter) as a support medium and is operated on a long-term basis. The reactor was inoculated with thermally pre-treated anaerobic sludge and operated with decreasing hydraulic retention time (HRT), from 8 h to 1 h, at a controlled temperature of 30 °C and a pH of about 3.8. Glucose (2000 mg L^?1) was used as the substrate, generating conversion rates of 92–98%. Decreasing the HRT from 8 h to 1 h led to an increase in average hydrogen-production rates, with a maximum value of 1.28 L h^?1 L^?1 for an HRT of 1 h. In general, hydrogen yield production increased as HRT decreased, reaching 2.29 mol of H₂/mol glucose at an HRT of 2 h and yielding a maximum hydrogen content of 37% in the biogas. No methane was detected in the biogas throughout the period of operation. The main soluble metabolites (SMP) were acetic acid (46.94–53.84% of SMP) and butyric acid (34.51–42.16% of SMP), with less than 15.49% ethanol. The steady performance of the AFBR may be attributed to adequate thermal treatment of the inoculum, the selection of a suitable support medium for microbial adhesion, and the choice of satisfactory environmental conditions imposed on the system. The results show that stable hydrogen production and organic acids production were maintained in the AFBR over a period of 178 days.     

The effects of Pt promotion on the oxi-reduction properties of alumina supported nickel catalysts for oxidative steam-reforming of methane: Temperature-resolved XAFS analysis

The effects of Pt trace addition on the oxi-reduction properties of the Ni/Al₂O₃ and Ni/La–Al₂O₃ catalysts during partial oxidation of methane (POM) and autothermal reforming of methane (ATR) were investigated. The xPt–Ni/yLa–Al₂O₃ catalysts containing 15 wt% of Ni, 0 or 12 wt% of La and 0 or 0.05 wt% of Pt were characterized by temperature-resolved X-ray absorption near edge structure (XANES) spectroscopy under various atmospheres.The in situ XANES analysis for Pt–Ni/Al₂O₃ under H₂ and CO revealed that the presence of Pt sites can initiate the NiO reduction process by rapid dissociation of H₂ and migration of atomic H to the NiO surface by hydrogen spillover. On the other hand, in situ XANES analysis under CH₄ showed that the presence of Pt sites induces the activation of the methane, probably by initial dissociation of methane (CH₄ → CH₃ + H) followed by migration of atomic H to the NiO surface. In situ XANES experiments under a POM mixture demonstrate that Pt has an important role keeping Ni in the metallic state. The catalytic test results for POM and ATR demonstrate that Pt is an important promoter to maintain Ni in the metallic state at the inlet region of the catalytic bed, where CH₄ and O₂ coexist.     

A 12-bit intrinsic accuracy high-speed CMOS DAC

A 12-bit intrinsic accuracy digital-to-analog (D/A) converter integrated in a standard digital 0.5 μm CMOS technology is presented. It is based on a current steering doubly segmented 6+2+4 architecture and requires no calibration, no trimming, or dynamic averaging. The differential nonlinearity (DNL) and integral nonlinearity (INL) are 0.3 and 0.6 least significant bits (LSB's), respectively. The measured glitch energy is 1.9 pV.s. For a 12-bit resolution, the converter reaches an update rate of 300 MS/s. By reducing the voltage supply of the latches to 2.0 V, the glitch energy is reduced to sub-pV.s, and the update rate reaches 500 MS/s, for a resolution of 8 bits. The worst case power consumption is 320 mW, and it operates from a single 3.3 V voltage supply. The die area is 3.2 mm²