Composite system well-being evaluation based on non-sequential Monte Carlo simulation

The reliability evaluation of composite power systems has historically been assessed using deterministic and probabilistic criteria and methods. The well-being approach was recently proposed in order to combine deterministic criteria with probabilistic methods and evaluates the system by healthy, marginal and risky states. This paper presents an efficient method for composite system well-being evaluation based on non-sequential Monte Carlo simulation. It is assumed that the system is coherent, and the frequency and duration indices are calculated by the conditional probability method. The system adequacy is evaluated by a non-linear power flow solved by the Newton–Raphson method and by an optimal power flow solved by the Interior Points method. Results are presented for the IEEE-RTS system with a constant load and with a variable load curve. It is demonstrated that the proposed method, as well as the assumed hypothesis, are valid and provide an efficient alternative for the well-being analysis of large scale power systems.     

A Male-produced Sex Pheromone from the Neotropical Redbanded Stink Bug, <Emphasis Type="Italic">Piezodorus guildinii</Emphasis> (W.)

The male-produced sex pheromone of the neotropical redbanded stink bug, Piezodorus guildinii (W.) (Hemiptera: Pentatomidae), a serious pest of soybean in Central and South America, was identified as the sesquiterpene hydrocarbon β-sesquiphellandrene by coupled gas chromatography–mass spectrometry and laboratory bioassays. The identity was confirmed by comparison with an authentic standard, and its absolute configuration was determined to be (7R)-(+)-β-sesquiphellandrene. The mean rate of release was approximately 40 ng d⁻¹ male⁻¹. The compound was found only in extracts from sexually mature males. Laboratory olfactometer bioassays showed that 200 ng of the synthetic compound applied to a filter paper strip was as attractive to female bugs as odors from five 15-d-old live males, an airborne extract from males, or the fraction of the extract that contained (7R)-(+)-β-sesquiphellandrene.     

Potential of mean force calculations on an L-type calcium channel model

To understand the mechanisms of Na⁺/Li⁺ permeation at submicromolarCa²⁺ concentrations, Na⁺/Li⁺ blocking at higher Ca²⁺ concentrations(10^-6–10^-4 M) and Ca²⁺ permeation at millimolar Ca²⁺ concentrations,we used our recently described L-type calcium channel model.For this purpose, we obtained potential of mean force (pmf)curves for the position change of one Na⁺ and one Ca²⁺ ion insidethe channel and for the position change of a second Ca²⁺ ionwhen the EEEE locus is coordinated to Ca²⁺. The pmf curves suggestthat (i) at submicromolar Ca²⁺ concentrations, because of thelow velocity of Ca²⁺ entry in the channel, monovalent ion fluxoccurs; (ii) at Ca²⁺ concentrations between 10^-6 and 10^-4 M,thermodynamic equilibrium between the channel and Ca²⁺ is achieved;as the coordination of Ca²⁺ with the locus is more favorablethan the coordination of Na⁺, the monovalent ion flux is blocked;and (iii) to put a second Ca²⁺ ion inside the channel at anappropriate rate, the Ca²⁺ concentration should reach millimolarlevels. Nevertheless, the entry of a second Ca²⁺ is thermodynamicallyunfavorable, indicating that the competition of two Ca²⁺ ionsfor the locus leads to Ca²⁺ permeation.     

Preliminary Studies on Furfural Production from Lignocellulosics

This study focused on the production of furfural from agricultural and industrial biomass residues by a hydrodistillation process. Corncobs, sugarcane bagasse, and eucalypt wood were treated with sulfuric, hydrochloric, and phosphoric acids as catalysts, with different acid concentrations (1.5 to 5.2 mol.L ^?1). In addition, the eucalypt liquor from the auto-hydrolysis, kraft-dissolving pulp production process was also investigated as a source of furfural, using sulfuric and hydrochloric acids as a catalyst (0.9 and 3.9 mol.L ^?1) . Furfural yields of 30.2, 25.8, and 13.9% were achieved for corncob, sugarcane bagasse, and eucalypt wood, respectively, on the basis of biomass dry weight. The efficiency of conversion from pentose to furfural using eucalypt liquor from the auto-hydrolysis kraft process was 71.5% using HCl 3.9 mol.L ^?1 . Due to the presence of a high amount of pentose, corncob produced the highest amount of furfural, followed by sugarcane bagasse and then eucalypt wood.     

Spray Drying of Green Corn Pulp

Maize (Zea mays) is a cereal grown in Brazil, and its availability is limited to the harvest season. An alternative processing route is based on the production of green corn powder, which has a longer shelf-life and increased versatility. This study aimed to evaluate the influence of drying conditions on the physical characteristics, size, and morphology of green corn powder. Drying experiments were performed on a spray dryer according to a central composite rotational design to evaluate inlet air temperature, feed flow rate, and pulp concentration. The yield of dried pulp corn had an average value of 36.19%. The following mean values for the physical properties of the powder were measured: solubility of 94.37 g/100 g, wettability of 128.05 seconds, moisture content of 1.97%, water activity of 0.13, density of 0.79 g/mL, and a particle diameter of 31.02 µm. The powder was also yellow with less intensity, and the particle surface was smooth at higher temperatures and had a tendency to form agglomerates. The estimated optimal conditions for spray drying were 48% (w/w) pulp concentration, 172°C inlet air temperature, and feed flow rate of 0.56 L/h.     

Polymorphism in Gd2Ge2O7 ceramics: Structural,vibrational, and optical features

In this work, Gd₂Ge₂O₇ polymorphs were obtained by solid-state reactions at 1100–1300 °C. Structural and vibrational features were investigated by X-ray diffraction and Raman spectroscopy. For the triclinic (space group P1) polymorph, all the predicted phonons were discerned in perfect agreement with the group theory calculations, while for the tetragonal polymorph (space group P4₁2₁2), 53 bands of the 81 predicted modes could be identified and characterized. The Gd³⁺ 4f-4f electronic transitions were investigated by diffuse reflectance spectroscopy in the range 200–340 nm. By applying the Kubelka-Munk function, it was possible to determine the bandgap values for all ceramics studied. The tetragonal polymorph exhibited higher bandgap values (5.88 eV) than the triclinic one (5.59 eV), which are both more energetic than other pyrochlore polymorphs reported in the literature. The results indicate that the presence of polymorphism in Gd₂Ge₂O₇ ceramics can be used to produce tailor-made materials since their crystal structures have a strong influence on their optical properties. Consequently, these properties could be used to tuning the optical properties of Gd-containing materials to sensitize and transfer energy to other luminescent lanthanide ions, aiming for innovative applications.     

Dual-layer hollow fibers for gas separation processes produced by quadruple spinning

A novel quadruple spinneret to produce dual-layer hollow fiber membranes by simultaneous spinning of two polymer solutions, using the dual precipitation bath technique is proposed. Hollow fibers aimed at gas separation processes were prepared in extrusion system specifically designed and built for this purpose. A polyurethane polymer was selected as the selective layer (outer-layer), while polyethersulfone was defined as the support (inner-layer). Activated carbon powder was added into the PU solution for further improvement of the transport properties. The hollow fibers showed good adhesion between the polymer layers and a defect-free selective layer. Representative results include a CO₂/N₂ selectivity of 43.