Transesterification of Soybean Oil Over Me/Al2O3 (Me = Na, Ba, Ca, and K) Catalysts and Monolith K/Al2O3-Cordierite

Four different Me/Al₂O₃ (Me = Na, Ba, Ca, and K) powder catalysts prepared by incipient-wetness impregnation, and a K/Al₂O₃-cordierite monolithic catalyst produced by the dipcoating technique were used for biodiesel production. The samples were characterized and studied in the transesterification of soybean oil with methanol at 120 °C and 500 rpm, with a alcohol/oil molar ratio = 32, and a catalyst load = 1 wt% for the powder catalyst and 0.5 wt% for the monolith. The Ca/Al₂O₃, Na/Al₂O₃ and K/Al₂O₃ powder catalysts reported a FAME (fatty acid methyl esters) formation of 94.7, 97.1, and 98.9% respectively after 6 h of reaction. On the other hand, Ba/Al₂O₃ showed little activity (7.6%). The leaching of the alkali and alkaline earth metal species during reaction was important, what indicates that the activity could be explained in terms of a homogeneous–heterogeneous catalyst effect. When the monolithic sample and the powder catalyst were compared (under identical reaction conditions), the production of FAME for the latter was 89.5–59.1% for the monolithic catalyst. After two consecutive runs, the monolithic catalyst presented a partial deactivation of 8% in the FAME yield. The present work shows that the use of monolithic catalysts in the transesterification of vegetable oils is a viable alternative.     

Insecticidal and repellency activity of essential oil of Eucalyptus sp. against Sitophilus zeamais Motschulsky (Coleoptera, Curculionidae)

BACKGROUND: The objective of this work was to evaluate the insecticidal and repellent effect of essential oils of Eucalyptus dunnii, E. saligna, E. benthamii, E. globulus and E. viminalis in the control of Sitophilus zeamais in maize grains. RESULTS: The essential oils chemical composition showed that the E. benthamii presents the cis‐ocimene (56.88%) as major compound. Results permitted us to verify that the evaluated species presented different insecticidal action under Sitophilus zeamais. About 100% of mortality was achieved with doses of 65, 100 and 400 µL for E. dunnii, E. saligna and E. benthamii, respectively. After regression analysis the LD₅₀ values were calculated and E. dunnii was shown to be the most efficient (25.03 µL), followed by E. saligna (37.93 µL) and E. benthamii (121.09 µL). Using the previously calculated LD₅₀ values, the repellency activity was calculated, allowing us to conclude that all species presented significant values in terms of this important parameter. CONCLUSION: The essential oil of Eucalyptus sp. presented insecticidal and repellency against Sitophilus zeamais Motschulsky (Coleoptera, Curculionidae). Although from an economic point of view synthetic chemicals are still more frequently used as repellents, natural products (essential oils) have the potential to provide efficient and safer repellents for humans and the environment. Copyright © 2010 Society of Chemical Industry     

Novel method to produce β-TCP scaffolds

The production of ceramic scaffolds by a novel method was reported in this work. The method comprised the mixture of colloidal silica and β-tricalcium phosphate (β-TCP) powder, where paraffin microspheres were further added to provide the porosity in the scaffold after firing. Thermo-gravimetric analysis showed that the paraffin was completely degraded before 550 °C, where the heat treatment at 1100 °C was enough to remove the paraffin and provide porosity and mechanical strength. The scaffold had an open porosity, but with poor pore interconnection. The density of the scaffold was 1.11 ± 0.03 g/cm³ with a porosity of 64.98 ± 1.1%, and the compression strength was 5.02 ± 1.2 MPa.     

Demineralized whey–gelatin composite films: Effects of composition on film formation,mechanical, and physical properties

In this study, the objective was to prepare and characterize films with different concentrations of demineralized whey (3–10%) and gelatin (1–3%) containing glycerol (10–70%) as a plasticizer and chitosan or nanochitosan as an additive. Mechanical properties, thickness, grammage, opacity, moisture content, water, and ethanol solubilities of the obtained films were determined. The formation of films without glycerol and gelatin was not possible. A higher gelatin concentration led to more desirable mechanical properties. Thickness, grammage, opacity, and moisture content remained almost constant after increasing gelatin concentration. Heightening glycerol concentrations raised water and ethanol solubility. Despite presenting high water solubility, the films showed low ethanol solubility. The formulation containing whey (3%), glycerol (20%), gelatin (3%), and chitosan (0.1%) resulted in the highest performing film concerning physical and mechanical aspects. Through Fourier transform infrared spectroscopy analysis, it was possible to observe the displacement and the frequency reduction of the band near 3,300 cm⁻¹, revealing different protein interactions. It indicates that hydrogen bonds occur between the amino group and  OH of the protein molecules reducing film hydrophilicity. Contact angle measurements also showed a less hydrophilic character. The films present the potential to prolong the shelf life of food, such as dairy products.     

An Efficient Approach to Semantic Segmentation

We consider the problem of semantic segmentation, i.e. assigning each pixel in an image to a set of pre-defined semantic object categories. State-of-the-art semantic segmentation algorithms typically consist of three components: a local appearance model, a local consistency model and a global consistency model. These three components are generally integrated into a unified probabilistic framework. While it enables at training time a joint estimation of the model parameters and while it ensures at test time a globally consistent labeling of the pixels, it also comes at a high computational cost.     

Influence of Nitrogen and Carbon Sources on Riboflavin Production by Wild Strain of Candida sp.

Microorganisms are capable of producing vitamins as metabolites, which are essential nutrients, in the metabolism of energy production. So, microbial production has been researched for years. Riboflavin is one of the fewest B-vitamins biotechnologically produced. There are many factors that affect riboflavin biosynthesis, which varies in each microorganism. However, few studies of the effect of different carbons and nitrogen sources on riboflavin production have been done. Thus, our objective in this study was to work on the effect of previously selected carbon and nitrogen sources on riboflavin production by screened wild-type yeast Candida sp. LEB 130. Classical shaken fermentation vessel system was used, controlling temperature and agitation, with fixed oxygen concentration. A 2⁵ screening design was used to analyze the effect of the medium components such as sucrose, flaxseed oil, and yeast extract. A second experiment factorial design 2⁴ yielded a riboflavin production of 105.7 ug/mL, 4.2-fold higher than 2⁵ design. Riboflavin analysis was done in a spectrophotometer. Screening design as a medium performance evaluation ended up being very advantageous for riboflavin production by this yeast.     

Effective removal of methylene blue from aqueous solution using a new magnetic iron oxide nanosorbent prepared by combustion synthesis

A magnetic iron oxide nanopowder (MnP) prepared by a new combustion technique was characterized and tested as adsorbent for methylene blue (MB) removal from aqueous solution. The effects of pH, adsorbent dose, initial dye concentration, contact time, and temperature on the amount of MB adsorbed were studied. The adsorption kinetics were described by a pseudo-second-order model, and the equilibrium experimental data were well fitted to the Langmuir isotherm, yielding a maximum adsorption capacity of 25.54 mg g^?1. The adsorption mechanism is governed by electrostatic forces and is highly dependent on the pH. The MnP adsorbent demonstrated excellent stability, showing good removal efficiency even after eight cycles of reuse, suggesting its potential large-scale application for the removal and recovery of MB from wastewater.     

Detection of similar successive groups in a model with diverging number of variable groups

Abstract

In this article, a linear model with grouped explanatory variables is considered. The idea is to perform an automatic detection of different successive groups of the unknown coefficients under the assumption that the number of groups is of the same order as the sample size. The standard least squares loss function and the quantile loss function are both used together with the fused and adaptive fused penalty to simultaneously estimate and group the unknown parameters. The proper convergence rate is given for the obtained estimators and the upper bound for the number of different successive group is derived. A simulation study is used to compare the empirical performance of the proposed fused and adaptive fused estimators, and a real application on the air quality data demonstrates the practical applicability of the proposed methods.     

Data Gathering in Wireless Sensor Networks Using Unmanned Aerial Vehicles

In an IoT world sensor-enabled systems are all around us and accessible for management at any time and place. Besides other technological components, small unmanned aerial vehicles are also expected to have an important role in IoT as they fly at low-altitude becoming suitable data acquisition vehicles in certain situations. In this article we focus on data gathering using unmanned aerial vehicles for applications having delivery limit constraints. The problem is to design an efficient set of paths to gather sensor data at specific places, and to deliver it at the sink node, while accomplishing the delivery limit associated with data. After formalizing the problem, a heuristic approach is developed that incorporates solution improvement mechanisms suitable for data gathering purposes. Results show that the proposed approach is suitable to solve the data gathering problem and clues on how to adjust parameters, according to the nature of the data set, are given.