Comparison of the catalytic performance of YIG garnets and Fe-containing oxides catalysts for oxidation of ethylbenzene

Iron-containing garnets (YIG) were used as catalysts for selective oxidation of ethylbenzene (EB) in the presence of H₂O₂ as oxidant. The catalysts comprising of two series of garnets e.g., Y₃(Fe_1–xZn_x)₅O₁₂ and Y₃(Fe_1–xNi_x)₅O₁₂ had distinct Zn and Ni contents (x = 0.00 0.01, 0.03, and 0.05). XRD, Raman and FTIR spectroscopies revealed that the cubic structure of Y₃Fe₅O₁₂ garnet was present for x = 0.00 and 0.01. For higher contents, the garnets had the Y₃Fe₅O₁₂ phase besides hematite (α-Fe₂O₃). The catalytic activity was dependent on the contents of metals in the garnets with Y₃Fe_4·97Ni_0·03O_12-γ and Y₃Fe_4·95Zn_0·05O_12-γ catalysts achieving better results. The influence of the reaction conditions such as reaction time, reaction temperature and effect of the solvents as well as the substrates to H₂O₂ molar ratios were studied. SEM-EDS, XPS and EPR results demonstrated the affinity of the Fe²⁺/Fe³⁺ pairs with Ni²⁺ species for the ethylbenzene molecule, which gave an EB conversion of 77% with a good production of acetophenone over the Y₃Fe_4·97Ni_0·03O_12-γ catalyst compared to other binary and ternary solids.     

Airborne-particle abrasion with niobium phosphate bioactive glass on caries-affected dentin: effect on the microtensile bond strength

This study evaluated the effect of airborne-particle abrasion with niobium phosphate bioglass (NbG) microparticles on the bond strength (μTBS) and longevity of an adhesive system to different dentin substrates. In this study, 18 Caries-free molars were used, of which 12 were microbiologically processed for caries induction. The dentin surfaces were evaluated in three groups: (1) Control – Healthy Dentin; (2) Partial removal of carious tissue; (3) complete removal of carious tissue. Half the teeth in each group were submitted to airborne-particle abrasion with NbG microparticles (15 s/1 cm/5 bar). After this, the adhesive Clearfil S³ was applied and composite buildups were constructed incrementally; and specimens were longitudinally sectioned to obtain bonded sticks (1.0 mm²) to be tested in tension (0.5 mm/min) immediately or after 6 months of storage in water. The fracture patterns were evaluated by stereomicroscope (40×) and then by scanning electron microscopy. The data were analyzed by the Kruskal-Wallis (post hoc Dunn) and Mann-Whitney tests (α = 0.05). Healthy dentin showed the highest bond strength (μTBS). Airborne-particle abrasion with NbG increased the μTBS values in the Group with complete caries removal. The bond strength values in the 24-h period were higher than those at 6 months. In the majority of the specimens the fracture mode was adhesive/mixed. The authors concluded that airborne-particle abrasion on dentin with NbG particles increased the μTBS in the group in which carious dentin was completely removed.     

Drying of Lentil Including Shrinkage: A Numerical Simulation

Abstract

This article presents a theoretical study about drying of lentil including shrinkage. The two-dimensional unsteady-state diffusion modeling written in the oblate spheroidal coordinates system considers the volume variation effect, convective boundary condition at the surface of the solid, and variable thermo-physical properties. The governing equation was discretized using the finite-volume method and the linear equations system was solved by Gauss-Siedel iterative method. To validate the model, numerical results of the average moisture content were compared with experimental data from eight experiments and a good agreement was obtained. The diffusion coefficients for all drying experiments are determined using the least square error technique.     

Factors associated with adiposity in normal weight female adolescents with adequate and high percent body fat: elaborating a risk model

Factors associated with adiposity in normal weight female adolescents with adequate and high percent body fat: elaborating a risk model. This study was carried out to evaluate the factors associated with adiposity in normal weight adolescents presenting appropriate or high percent body fat, who attended the public schools in Vi?osa county-Minas Gerais/Brazil. A total of 118 female adolescents at age range from 14 to 19 years and have already presented the menarche were evaluated. The adolescents were divided into 2 groups: G1 with high percent body fat and G2 with appropriate percent body fat. The following variables were evaluated: anthropometric, body composition, lifestyle and the family history of non-communicable chronic diseases. In subsample, the basal energy consumption was determined by indirect calorimetry. The G1-grouped adolescents showed higher values for most anthropometric and body composition variables (p < 0.001). No differences were observed (p > 0.05) for basal metabolism and metabolism of lean body mass, smoking habit, total energy consumption and protein and lipid as well between groups. When comparing the physical activity level, the G1 adolescents spent more time with 1-level sedentary activities whereas the G2 ones showed higher total caloric consumption with daily activities (p < 0.001). According to risk factors under analysis, the variables related to lifestyle, as distinguishing the use of sweeteners (OR = 13.47), provided higher contribution to excessive adiposity in the normal weight adolescents. The detailed analysis of the body composition as well as the risk factors associated with excessive body fat makes possible the early diagnosis and the development of more appropriate intervention means.     

Nematode Root Herbivory in Tomato Increases Leaf Defenses and Reduces Leaf Miner Oviposition and Performance

The outcome of plant-mediated interactions among herbivores from several feeding guilds has been studied intensively. However, our understanding on the effects of nematode root herbivory on leaf miner oviposition behavior and performance remain limited. In this study, we evaluated whether Meloidogyne incognita root herbivory affects Tuta absoluta oviposition preference on Solanum lycopersicum plants and the development of the resulting offspring. To investigate the M. incognita-herbivory induced plant systemic responses that might explain the observed biological effects, we measured photosynthetic rates, leaf trypsin protease inhibitor activities, and analyzed the profile of volatiles emitted by the leaves of root-infested and non-infested plants. We found that T. absoluta females avoided laying eggs on the leaves of root-infested plants, and that root infestation negatively affected the pupation process of T. absoluta. These effects were accompanied by a strong suppression of leaf volatile emissions, a decrease in photosynthetic rates, and an increase in the activity of leaf trypsin protease inhibitors. Our study reveals that root attack by nematodes can shape leaf physiology, and thereby increases plant resistance.     

Polymorphic transformation morphology of isotactic poly(1-butene)/poly(propylene-co-1-butene-co-ethylene) blends

The aim of this work was to investigate the polymorphic transformation morphology of isotactic poly(1-butene) (iPB-1) in blends with poly (propylene-co-1-butene-co-ethylene) (terPP). The blends were prepared by solution casting followed by compression-molding and were examined immediately after preparation as well as after aging for over 30 days. Morphological changes were firstly observed by polarized optical microscopy, which showed that the terPP promotes the reduction of the spherulite mean size during the crystallization of iPB-1 from the melt. Digital pulsed force microscopy provided data about the terPP interspersion between the interfibrilar and spherulitic regions of the iPB-1 crystals, causing iPB-1 spherulite deformation. However, a better distribution of the amorphous component on the iPB-1 crystals was observed after phase II to I transition, favored by the rearrangement of iPB-1 lamellae and lamellar stacks during phase transition.     

High‐fat diet based on trienantin has no adverse metabolic effects in rats

The present study was designed to evaluate the metabolic effects of a high‐fat diet based on trienantin, an uncommon medium‐odd‐chain triacylglycerol. Male Wistar rats (33.37 ± 5.69 g) (n = 3×10) were maintained for 6 weeks on a control diet (7 g soya oil/100 g) or a high‐fat diet based on trienantin (40 g margarine, 4 g soya oil and 25.79 g trienantin/100 g), or a high‐fat diet based on soya oil (40 g margarine and 29.79 g soya oil/100 g). The serum lipid profile, hepatic function and injury markers, and renal function and injury markers were determined. Samples of liver, stomach, kidney and small intestine were collected for histological analysis. The animals fed the high‐fat diet based on trienantin exhibited a lower body weight gain in relation to the control group, between the second and fifth week of the experiment. There were no differences amongst the biochemical markers of the three groups (p ≥0.05). Lipid infiltration of the hepatocytes was detected in a similar manner in all groups (p ≥0.05). These data demonstrate that the high‐fat diet based on trienantin did not promote adverse metabolic effects under the conditions of this study. This could serve as a reference parameter in the evaluation of the safety of its therapeutic application.     

AC Conductivity of Porous Silicon from Monte Carlo Simulations

The AC conductivity of a percolation model with local energetical disorder for porous Silicon in three dimensions, (), is studied by Monte Carlo simulations. The model includes both diffusion and recombination processes and () is obtained by a Fourier transform of the mean-square displacement of the carriers, where hopping diffusion of a single type of carrier (either an electron or an exciton) and two types of carriers (an electron and a hole) are considered. It is found that at low temperatures, the behavior of () depends sensitively on the type of carrier considered.     

Dynamic mechanical and morphological behavior of blends of polystyrene and poly[acrylonitrile‐g‐(ethylene‐co‐propylene‐co‐diene)‐g‐styrene] prepared by in situ polymerization of styrene

PS/AES blends were prepared by in situ polymerization of styrene in the presence of AES elastomer, a grafting copolymer of poly(styrene‐co‐acrylonitrile) – SAN and poly(ethylene‐co‐propylene‐co‐diene)–EPDM chains. These blends are immiscible and present complex phase behavior. Selective extraction of the blends' components showed that some fraction of the material is crosslinked and a grafting of PS onto AES is possible. The morphology of the noninjected blends consists of spherical PS domains covered by a thin layer of AES. After injection molding, the blends show morphology of disperse elastomeric phase morphology in a rigid matrix. Two factors could contribute to the change of morphology: (1) the stationary polymerization conditions did not allow the mixture to reach the equilibrium morphology; (2) the grafting degree between PS and AES was not high enough to ensure the morphological stability against changes during processing in the melting state. The drastic change of EPDM morphology from continuous to disperse phase has as consequence a decrease in the intensity of the loss modulus peaks corresponding to the EPDM glass transition. However, the storage modulus at temperatures between the glass transition of EPDM and PS/SAN phases does not change significantly. This effect was attributed to the presence of the SAN rigid chains in the AES. © 2009 Wiley Periodicals, Inc. Journal of Applied Polymer Science, 2009     

Near-stoichiometric silicon carbide from a poly(methylsilylene)/tetra-allylsilane mixture

This paper describes the use of a bi-component mixture of poly(methylsilylene), PMS, and tetra-allylsilane, TAS, in variable composition, as a pyrolytic precursor to SiC. The ceramic products were characterized by elemental analysis, 29Si MAS NMR, actual density measurements, XRD and TEM. The PMS/TAS mixture produces, in an appropriate ratio, near-stoichiometric SiC with an apparent composition of 99% SiC and 1% C, after pyrolysis up to 1000 °C under inert atmosphere, in a reasonable yield.