Electronic Structure and Half-Metallic Character in Sr2CoB′O6 (B′ = Mo, Re) Materials

We report several ab initio calculations performed for Sr₂CoB′O₆ (B′ = Mo, Re) by means of the Density Functional Theory and the Linearized Augmented Plane Waves method with spin polarization. For the calculations, the exchange and correlation potentials were included through the local density LDA+U approximation with B3PW91. Density of states (DOS) study was carried out considering both up and down spin polarizations by the Generalized Gradient Approximation (GGA). From the Murnaghan state equation, we calculate the cell dimensions that minimize the total energy. Our results of DOS calculations show that the Sr₂CoMoO₆ material presents a metallic behavior, while Sr₂CoReO₆ reveals a half-metallic nature with conductor behavior for the spin down orientation and semiconducting feature for spin up channel. It was observed close to Fermi level that the low-energy spin down states of Co are responsible by the majority contribution to conduction band. The calculated effective cell magnetic moment of the Sr₂CoReO₆ compound evidences a value 2.02 μ _B , which is close to an integer number as expected for a half-metallic material.     

LINEAR PI TEMPERATURE-CONCENTRATION CASCADE CONTROL FOR TUBULAR REACTORS

In this article we explore the application of linear PI cascade control schemes to improve the performance of industrial PI/PID controllers for controlling outlet reactor concentration. By departing from simple I/O first-order dynamical models obtained from step responses, it is shown that the incorporation of a secondary loop for regulating the reactor temperature at a given interior position significantly improves the control performance in the face of feed composition and temperature disturbances. The effects of the temperature sensor location and the usage of multiple temperature measurements are also evaluated.     

Adaptive photodetector for assisted Talbot effect

We use an adaptive photodetector for measuring the visibility of the Fresnel diffraction patterns generated by a grating. Visibility is measured in real time, with high spatial resolution, and without any signal processing. This method is well suited for analyzing the Talbot effect and its many applications.     

Parametric Study on the Production of Renewable Fuels and Chemicals from Phospholipid-Containing Biomass

Heterogeneous catalytic cracking of lipids into transportation fuels and other specialty chemicals offers a unique opportunity to provide sustainable energy while utilizing the current petroleum infrastructure. This study addresses a possible route for the utilization of phospholipid-containing biomass for production of renewable fuels and chemicals. The first part of the study focused on reaction pathways associated with the catalytic cracking of model phospholipid into fuel-type compounds. The results indicated that phospholipid cracking proceeds via acid-catalyzed mechanisms, which resulted to cleavage of fatty acids and glycerol moieties. Microbial lipids, which contain large concentrations of phospholipids, are a potential non-food related feedstock to displace petroleum. Among possible sources of microbial lipids, activated sludge offers a distinct advantage for its availability and abundance at a potential fee. The second part of this work dealt with the conversion of activated sludge to chemicals of value as fuel components through fluidized-bed catalytic cracking. The effect of moisture level and catalyst loading were determined. Results indicated that moisture level of up to 15 % (weight) has no effect on total product yield. On the other hand, higher catalyst loading resulted to a higher yield of gaseous product. Significant coke deposition was inferred as indicated by the high proportion of phenolic compounds produced from pyrolytic reactions. The results of this study provide a potential route of utilizing bulk lipid feedstocks, without the removal of phosphorus-containing molecules, to produce fuel components.     

Nutritional behavior of cyclists during a 24-hour team relay race: a field study report

Background  

Information about behavior of energy intake in ultra-endurance cyclists during a 24-hour team relay race is scarce. The nutritional strategy during such an event is an important factor which athletes should plan carefully before the race. The purpose of this study was to examine and compare the nutritional intake of ultra-endurance cyclists during a 24-hour team relay race with the current nutritional guidelines for endurance events. Additionally, we analyzed the relationship among the nutritional and performance variables.     

Differentiation of the raw material of the Iberian pig meat industry based on the use of amplified fragment length polymorphism

The present study is the first step of the development of a new analytical technique to discriminate the genotypes of purebred Iberian and crossbred Iberian×Duroc pigs. A DNA test of breed identity has clear advantages for the protection of the brand name of high-prized products of purebred Iberian pigs. Amplified fragment length polymorphism procedure was used to analyze the genomic DNA samples of 77 Duroc and 80 Iberian pigs from the most representative populations. Thirteen primer combinations produced 588 amplified fragments. A total number of 139 fragments were polymorphic and 14 out of them were detected in Duroc and never in Iberian pigs. A panel of the nine most frequent markers allows the discrimination between purebred and crossbred animals. The values of the probability of exclusion of the pure Iberian origin (P(EC)) were 0.97 and 0.78, for crossbred individuals with 50 or 25% of Duroc genes, respectively.     

Modulus of elasticity of I-214 young poplar wood from standing trees to sawn timber: influence of the age and stand density

The poplar wood industry chain from planted forests takes a strategic position for the creation of a competitive, profitable, and highly technological bioeconomy in the world. Niche sectors such as buildings can find in poplar wood an effective ally to reduce its carbon footprint and ecological backpack. For the poplar wood, it is important to understand the huge significance of the proper silvicultural management of a plantation and to characterize the raw material. In this context, this paper carries out such characterization for the particular case of young plantations of the clone I-214 (Populus × euroamericana (Dode) Guinier), commonly used for its high growth rate. The acoustic non-destructive characterization of poplar wood is carried out from standing trees, logs and sawn timber and then compared with the one obtained through destructive mechanical tests. The study shows that growth parameters are highly affected by the age and moderately affected by stand density, while mechanical properties are strongly affected by the age and less affected by the stand density. The study also shows high values of the linear regression coefficients between the mechanical properties obtained on standing trees, logs, and sawn timber using non-destructive and destructive methods (R²?=?0.7 for all three cases), greater than those obtained for other species. A good linear fitting was obtained between the tree and log velocities (R²?=?0.76) and between the tree and log elastic moduli (R²?=?0.85). Consequently, the evaluation of the mechanical properties employing the optimized acoustic protocol provides a reliable characterization for the poplar wood.

     

Characterization of perylene diimide dye self-assemblies and their use as templates for the synthesis of hybrid and supermicroporous nanotubules

The self-organizing structures formed by a water-soluble perylene diimide dye (PDI) have been studied by several experimental techniques as potential templates for the preparation of hybrid nanomaterials. The dye forms chromonic-nematic and hexagonal liquid crystals in water. The aggregates in liquid crystals consist of one-molecule-wide stacks. From the changes in the solution proton NMR chemical shifts with concentration, it appears that adjacent molecules are twisted. There is significant broadening of the aromatic resonances at higher concentrations, arising from nonmotionally averaged dipole-dipole coupling between adjacent aromatic hydrogens. This is attributed to slow overall rotation of the aggregates in solution, suggesting that they grow up to several tens of nanometers. Dye aggregates serve as templates for the formation of silica tubules (1-5 μm length, average diameter ≈300 nm), with aligned and very thin (1-2 nm) dye nanostripes embedded in the walls. The silica tubes precipitated from solution are formed by the cooperative interaction between PDI and silica species during the sol-gel reaction. Upon calcination, silica nanotubules with supermicroporous walls are obtained. In comparison with conventional surfactant systems, the use of π-π stacked chromonic aggregates brings new possibilities for the templated fabrication of pores with sizes below the mesoporous range. Materials could find applications in photovoltaics as well as in shape selective catalysis and adsorption.     

Procedures for Determining Maximum Emitter Discharge in Subsurface Drip Irrigation

One problem associated with subsurface drip irrigation (SDI) is the reduction in discharge resulting from soil-water back-pressure at the emitter outlets. An experimental setup was made to measure emitter discharge and pressure at the emitter outlet in different soils. Experiments were carried out with 2–24??L/h noncompensating and compensating emitters, operating at a constant lateral pressure of 10?m. Emitter discharge was reduced to a range of 2–10% for noncompensating models and to less than 1% for compensating models. Soil pressure ranged from 0.15–2.07?m. Laboratory conditions were simulated with HYDRUS-2D/3D. Experimental values of discharge and soil pressure showed good agreement with estimated values. Finally, maximum emitter discharge to limit the decrease of discharge was determined for an operating pressure of 10?m. For a 10% decrease, considering a constant radius of the spherical cavity in the soil, maximum emitter discharge was 2.35??L/h for loamy soil and 12.44??L/h for sandy soil for noncompensating emitters, and 10.73 and 54.51??L/h, respectively for compensating emitters. These values increased when considering a cavity radius variable with emitter discharge.     

Fast multiscale modeling of cardiac electrophysiology including Purkinje system

In this paper, we present a modeling methodology to couple the cardiac conduction system to cardiac myocytes through a model of Purkinje-ventricular junctions to yield fast and realistic electrical activation of the ventricles. A patient-specific biventricular geometry is obtained from processing computed tomography scan data. A one-manifold implementation of the fast marching method based on Eikonal-type equations is used for modeling heart electrophysiology, which facilitates the multiscale 1-D-3-D coupling at very low computational costs. The method is illustrated in in-silico experiments where we analyze and compare alternative pacing strategies on the same patient-specific anatomy. We also show very good agreement between the results from the proposed approach and more detailed and comprehensive biophysical models for modeling cardiac electrophysiology. The effect of atrioventricular delay on the distribution of activation time in myocardium is studied with two experiments. Given the reasonable computational times and realistic activation sequences provided by our method, it can have an important clinical impact on the selection of optimal implantation sites of pacing leads or placement of ablation catheter's tip in the context of cardiac rhythm management therapies.