Polyvinyl chloride composites filled with olive stone flour: Mechanical,thermal, and water absorption properties

The production of olive oil leads to considerable amounts of solid waste mainly composed of hard woody endocarp called olive stones. The aim of this work is to explore the possible use of ground olive stones as fillers for polyvinyl chloride (PVC), to elaborate a cost‐effective composite material with a solid loading of up to 50 wt %. After grinding, the ensuing olive stone flour (OSF) was incorporated into a PVC matrix via melt compounding and injection molding to elaborate PVC‐OSF‐based composites with a filler content up to 50 wt %. The evolution of the mechanical performance, the impact property, the water absorbance, and wear resistance behavior, according to the OSF content, were investigated. The addition of OSF was shown to enhance the stiffness of the matrix, but at the expense of its mechanical strength. However, the strength of the composite did not fall as low as 30 MPa, and therefore, meets the requirements for many applications in plastic‐based materials. The thermal properties of the ensuing composites were also studied by thermogravimetric analysis. The results show that the addition of OSF may be effective in increasing the stiffness of the PVC‐based composite and in reducing the solid residue in the olive oil industry production. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41083.     

Laboratory and gas-fired furnace performance tests of epoxy primers for intumescent coatings

Protection of steel structures, using so-called intumescent coatings, is an efficient and space saving way to prolong the time before a building, with load bearing steel constructions, collapses in the event of a fire. In addition to the intumescent coating, application of a primer may be required, either to ensure adhesion of the intumescent coating to the steel or to provide corrosion resistance. It is essential to document the performance of the intumescent coating together with the primer to ensure the overall quality of coating system. In the present work, two epoxy primers were used to investigate the potential failure mechanism of a primer applied prior to an intumescent coating. The analysis was carried out using; (1) gas-fired test furnace, (2) a specially designed electrically heated oven, and (3) thermo gravimetric analysis. When tested below an acrylic intumescent coating, exposed to a gas-fired furnace following the ISO834 fire curve (a so-called cellulosic fire), one of the primers selected performed well and the other poorly. From tests in the electrically heated oven, it was found that both primers were sensitive to the film thickness employed and the presence of oxygen. At oxygen-rich conditions, higher primer thicknesses gave weaker performance. In addition, a color change from red to black was observed in nitrogen, while the color remained red in the oxygen–nitrogen mixture. In summary, the results suggest that an adequate choice of primer, primer thickness, and intumescent coating is essential for a good performance of an intumescent coating system.     

Bismuth-catalyzed and doped silicon nanowires for one-pump-down fabrication of radial junction solar cells

Silicon nanowires (SiNWs) are becoming a popular choice to develop a new generation of radial junction solar cells. We here explore a bismuth- (Bi-) catalyzed growth and doping of SiNWs, via vapor-liquid-solid (VLS) mode, to fabricate amorphous Si radial n-i-p junction solar cells in a one-pump-down and low-temperature process in a single chamber plasma deposition system. We provide the first evidence that catalyst doping in the SiNW cores, caused by incorporating Bi catalyst atoms as n-type dopant, can be utilized to fabricate radial junction solar cells, with a record open circuit voltage of V(oc) = 0.76 V and an enhanced light trapping effect that boosts the short circuit current to J(sc) = 11.23 mA/cm(2). More importantly, this bi-catalyzed SiNW growth and doping strategy exempts the use of extremely toxic phosphine gas, leading to significant procedure simplification and cost reduction for building radial junction thin film solar cells.     

Balancing Intermolecular and Molecule–Substrate Interactions in Supramolecular Assemblies

Self‐assembly of functional supra‐molecular nanostructures is among the most promising strategies for further development of organic electronics. However, a poor control of the interactions driving the assembling phenomena still hampers the tailored growth of designed structures. Here exploration of how non‐covalent molecule‐substrate interactions can be modified on a molecular level is described. For that, mixtures of DIP and F16CuPc, two molecules with donor and acceptor character, respectively are investigated. A detailed study of their structural and electronic properties is performed. In reference to the associated single‐component layers, the growth of binary layers results in films with strongly enhanced intermolecular interactions and consequently reduced molecule‐substrate interactions. This new insight into the interplay among the aforementioned interactions provides a novel strategy to balance the critical interactions in the assembly processes by the appropriate choice of molecular species in binary supra‐molecular assemblies, and thereby control the self‐assembly of functional organic nanostructures.     

Matrix effects on the bioavailability of resveratrol in humans

The pharmacokinetics of resveratrol in 11 healthy male volunteers has been assessed in a randomized, crossover, controlled clinical trial after the administration of three grape products: red wine (250 mL), grape juice (1/L), or tablets (red wine extracts enriched with trans-resveratrol). Doses of trans-resveratrol independently of the product administered, were about 14 μg/kg. Biological samples were collected and analysed by capillary gas chromatography–mass spectrometry. cis-Resveratrol, trans-resveratrol and dihydroresveratrol were determined in plasma and urine. Plasma concentration of trans-resveratrol after hydrolysis increased as a response to all grape products and that of cis-resveratrol after wine and grape juice. Free forms of these phenolic compounds were deemed undetectable in plasma. Despite similar trans-resveratrol doses being administered, its bioavailability from wine and grape juice was 6-fold higher, than that from tablets. Resveratrol was better absorbed from natural grape products than from tablets, pointing out the importance of the matrix in its bioavailability.     

Effect of temperature and pretreatment on water diffusion during rehydration of dehydrated mangoes

The kinetics associated with rehydrating dehydrated mangoes was studied at three temperatures: 25, 40, and 60 °C. Besides, we studied how rehydration was affected by pretreating the fruit with osmodehydration in either sucrose or glucose before it was thermally dehydrated. We show that rehydration can be interpreted by Fickian diffusion and that the effective water diffusion coefficient is larger at 40 °C than at either 25 or 60 °C. Consequently, during rehydration of untreated samples at 40 °C, the weight gain, water gain, and loss of solids attain optimal values. We found that the rehydration kinetics of mango was not affected by osmodehydration pretreatments in sucrose. However, pretreatment in glucose significantly improved rehydration; for example, the effective diffusion coefficients of the glucose-treated samples were about twice as large as those of the untreated samples.     

Structural Analysis of Masonry Historical Constructions. Classical and Advanced Approaches

A review of methods applicable to the study of masonry historical construction, encompassing both classical and advanced ones, is presented. Firstly, the paper offers a discussion on the main challenges posed by historical structures and the desirable conditions that approaches oriented to the modeling and analysis of this type of structures should accomplish. Secondly, the main available methods which are actually used for study masonry historical structures are referred to and discussed. The main available strategies, including limit analysis, simplified methods, FEM macro- or micro-modeling and discrete element methods (DEM) are considered with regard to their realism, computer efficiency, data availability and real applicability to large structures. A set of final considerations are offered on the real possibility of carrying out realistic analysis of complex historic masonry structures. In spite of the modern developments, the study of historical buildings is still facing significant difficulties linked to computational effort, possibility of input data acquisition and limited realism of methods.     

Propagation of measurement noise through backprojection reconstruction in electrical impedance tomography

A framework to analyze the propagation of measurement noise through backprojection reconstruction algorithms in electrical impedance tomography (EIT) is presented. Two measurement noise sources were considered: noise in the current drivers and in the voltage detectors. The influence of the acquisition system architecture (serial/semi-parallel) is also discussed. Three variants of backprojection reconstruction are studied: basic (unweighted), weighted and exponential backprojection. The results of error propagation theory have been compared with those obtained from simulated and experimental data. This comparison shows that the approach provides a good estimate of the reconstruction error variance. It is argued that the reconstruction error in EIT images obtained via backprojection can be approximately modeled as a spatially nonstationary Gaussian distribution. This methodology allows us to develop a spatial characterization of the reconstruction error in EIT images.     

An efficient combination of digital predistortion and OFDM clipping for power amplifiers

This article presents a strategy for enhancing efficiency in power amplifiers (PAs) by combining digital predistortion (DPD) linearization and clipping strategies for orthogonal frequency division multiplexing signals in a WiMAX scenario. On the one hand, by reducing the peak‐to‐average power ratio of multicarrier signals using the well‐known clipping technique, it is possible to perform a more efficient PA amplification. On the other hand, nonlinear and linear distortion introduced by the PA operating close to saturation is compensated by the baseband adaptive DPD linearizer. The DPD has to counteract not only the PA nonlinear behavior, but also its dynamics. A test‐bench implementing a WiMAX transmitter was deployed to evaluate the possibilities for enhancing power efficiency while fulfilling the demanded linearity requirements. Experimental results showing the power efficiency and linearity enhancement achieved by the proposed strategy are provided. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.