Specimen geometry and specimen size dependence of the $${\mathcal {}}$$-curve and the size effect law from a cohesive model point of view

The directionality of electromagnetic radiation from tensile fracturing is calculated within our previously proposed model and shown to agree with experimental observations in the field. The best locations and orientations of measuring antennas are presented.     

Engineered silica nanoparticles as additives in lubricant oils

Silica nanoparticles (SiO₂ NPs) synthesized by the sol–gel approach were engineered for size and surface properties by grafting hydrophobic chains to prevent their aggregation and facilitate their contact with the phase boundary, thus improving their dispersibility in lubricant base oils. The surface modification was performed by covalent binding of long chain alkyl functionalities using lauric acid and decanoyl chloride to the SiO₂ NP surface. The hybrid SiO₂ NPs were characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, simultaneous differential thermal analysis, nuclear magnetic resonance and dynamic light scattering, while their dispersion in two base oils was studied by static multiple light scattering at low (0.01% w/v) and high (0.50%w/v) concentrations. The nature of the functional layer and the functionalization degree seemed to be directly involved in the stability of the suspensions. The potential use of the functional SiO₂ NPs as lubricant additives in base oils, specially designed for being used in hydraulic circuits, has been outlined by analyzing the tribological properties of the dispersions. The dendritic structure of the external layer played a key role in the tribological characteristics of the material by reducing the friction coefficient and wear. These nanoparticles reduce drastically the waste of energy in friction processes and are more environmentally friendly than other additives.     

Indirect monitoring of TORC1 signalling pathway reveals molecular diversity among different yeast strains

Saccharomyces cerevisiae is the main species responsible for the alcoholic fermentation in wine production. One of the main problems in this process is the deficiency of nitrogen sources in the grape must, which can lead to stuck or sluggish fermentations. Currently, yeast nitrogen consumption and metabolism are under active inquiry, with emphasis on the study of the TORC1 signalling pathway, given its central role responding to nitrogen availability and influencing growth and cell metabolism. However, the mechanism by which different nitrogen sources activates TORC1 is not completely understood. Existing methods to evaluate TORC1 activation by nitrogen sources are time-consuming, making difficult the analyses of large numbers of strains. In this work, a new indirect method for monitoring TORC1 pathway was developed on the basis of the luciferase reporter gene controlled by the promoter region of RPL26A gene, a gene known to be expressed upon TORC1 activation. The method was tested in strains representative of the clean lineages described so far in S. cerevisiae. The activation of the TORC1 pathway by a proline-to-glutamine upshift was indirectly evaluated using our system and the traditional direct methods based on immunoblot (Sch9 and Rps6 phosphorylation). Regardless of the different molecular readouts obtained with both methodologies, the general results showed a wide phenotypic variation between the representative strains analysed. Altogether, this easy-to-use assay opens the possibility to study the molecular basis for the differential TORC1 pathway activation, allowing to interrogate a larger number of strains in the context of nitrogen metabolism phenotypic differences.     

Improving the Interoperability in the Digital Home Through the Automatic Generation of Software Adapters from a SysML Model

This paper addresses the motion planning problem of nonholonomic robotic systems. The system’s kinematics are described by a driftless control system with output. It is assumed that the control functions are represented in a parametric form, as truncated orthogonal series. A new motion planning algorithm is proposed based on the solution of a Lagrange-type optimisation problem stated in the linear approximation of the parametrised system. Performance of the algorithm is illustrated by numeric computations for a motion planning problem of the rolling ball.     

A simple method to generate spontaneous chemisorption of metallic particles mediated by carboxylate groups from silylated oligomeric poly(amide‐imide)s

The present work describes oligomeric poly(amide‐imide)s (PAIs) containing several l ‐amino acidic residues and two silicon atoms in their repeat unit, whose carboxylate terminal group was chemisorbed onto metallic particles (Cu, Ag or Au) previously deposited in controlled conditions via physical vapor deposition. Thus, for each prepared polymer–metallic hybrid, the surface morphology, particle size distribution, and percentage of organic material, silicon and metal were studied using scanning electron microscopy and energy‐dispersive X‐ray spectroscopy. The results show that the hybrids are formed probably via electrostatic interaction between the carboxylate anions of the PAIs and nanoparticle cations. This bridging ligand was visualized using Raman spectroscopy and corroborated with X‐ray diffraction. Optical studies and resistivity measurements (conductivity) of each hybrid were developed using UV‐visible and the four‐point probe method, respectively. X‐ray photoelectron spectroscopy was used to study the oxidation states of the metallic particles at surface level. Thus, a simple and spontaneous protocol is proposed for the preparation of metallic particles stabilized in situ by an oligomer, a procedure that takes place from seconds to a few minutes. Finally, particle diameters were measured using atomic force microscopy in order to study possible agglomeration of the metallic particles with time. © 2017 Society of Chemical Industry     

Antioxidant and Antimicrobial Activity of Commercial Propolis Extract in Beef Patties

The objective of this study was to evaluate the efficacy of propolis extract (PE) to reduce lipid oxidation and microbial growth on beef patties during refrigerated storage. Beef patties were manufactured by incorporating PE in 4 different treatments: (1) Control (no PE addition); (2) commercial propolis 1 (2% w/w; CP1); (3) commercial propolis 2 (2% w/w; CP2); and (4) noncommercial propolis (2% w/w; NCP). Raw patties were wrapped with polyvinyl chloride and stored at 2 °C for 8 d. Total phenolic content (TPC), free‐radical scavenging activity (FRS), and polyphenolic content of the PE were evaluated using high‐performance liquid chromatography (HPLC). Lipid oxidation (thiobarbituric acid‐reactive substances (TBARS), conjugated dienes (CnDs), metmyoglobin (MetMb%), pH variation, and color (L*, a*, b*, C*, and h*), and microbial growth (mesophilic and psychrotrophic bacteria) of patty samples were measured. NCP treatment demonstrated the highest FRS (64.8% at 100 μg/mL), which correlated with TPC and the presence of polyphenolic compounds. Lipid oxidation (78.54%, TBARS; 45.53%, CnD; 58.57%, MetMb) and microbial mesophilic and psychrotrophic growth (19.75 and 27.03%, respectively) values were reduced by NCP treatment in refrigerated samples after 8 d. These results indicate that PE has great potential as a natural antioxidant and antimicrobial additive to extend the shelf life of beef patties.     

Comparative study on skills needed by organizations and effectively developed in eLearning management courses

Universal Access in the Information Society - This paper investigates the skills developed in higher education management courses through an eLearning process. The relevance of this research is...