Assessment of olive cake as soil amendment for the controlled release of triazine herbicides

Organic matter-rich agricultural by-products are being produced in huge quantities and can be applied to soil as a disposal strategy. The application of two different rates (2 and 8% w/w) of olive cake to a Mediterranean calcareous soil resulted in an increased sorption of four triazine herbicides, which was higher for the more hydrophobic compounds (terbuthylazine and prometryn) and lower for the more polar ones (simazine and cyanazine). However, when the sorption coefficients were normalised to the total soil organic carbon (K(oc)), the results did not significantly differ between simazine and cyanazine which is an indication that the olive cake did not exert different sorption capacity for both compounds. On the contrary, K(oc) values for terbuthylazine and prometryn increased in the amended soils. Our results from experiments using mixtures of several pesticides suggest that competition for sorption sites resulted in a decrease of herbicide sorption. Desorption was hysteretical both for the amended and unamended soils, but the addition of olive cake at the highest dose diminished desorption of most of the herbicides. In conclusion, the addition of olive cake behaves as a promising method for reducing the risk of groundwater pollution by pesticides.     

Monitoring particle adsorption by use of laser reflectometry near the critical angle

We investigate the use of laser reflectometry near the critical angle to monitor particle adsorption onto a flat glass surface. Experimental results show that positive particles are adsorbed onto the glass surface and that their adsorption kinetics depend strongly on the volume fraction occupied by the particles in suspension but not appreciably on the particle size. The reflectance near the critical angle is dominated by the particles on the surface, with the contribution of the particles in suspension being very low. We compare the reflectance change near the critical angle with the change in reflectance near the Brewster angle when particles are adsorbed onto the glass surface. We find that reflectometry near the critical angle is 3000 times more sensitive than it is near the Brewster angle. Some optical images are presented to validate our results.     

Parameter estimation in emulsion copolymerization using reaction calorimeter data

The feasibility of estimating the kinetic parameters of emulsion copolymerization using only calorimetric measurements was investigated by simulation. It was found that for the case in which the average number of radicals per particle exceeds 0.5 only two of the three estimable parameters (k_I, k_a, and k_t) could be estimated together provided that an accurate value for the third parameter is available from independent measurements. For systems with n?<0.5, the three unknown parameters k_I, k_d, and k_a were accurately estimated. © 1995 John Wiley & Sons, Inc.     

Tunable Drug Loading and Reinforcement of Polycaprolactone Films by Means of Electrospun Nanofibers of Glycolide Segmented Copolymers

Electrospinning of a segmented copolymer having polyglycolide hard segments is successfully performed from 1,1,1,3,3,3‐hexafluoroisopropanol solutions. During the process, a bactericidal agent, i.e., chlorhexidine (CHX), is effectively loaded, which results in nanofibers with a smaller diameter because of the change in solution conductivity. New fabrics based on molding of alternate layers of poly(ε‐caprolactone) (PCL) films and the electrospun scaffolds of the segmented copolymer are prepared and characterized. The thermal molding process renders a PCL matrix homogeneously reinforced with nanofibers that compensate for the loss of mechanical properties caused by incorporation of CHX. Release of CHX is evaluated in different media. Results vary depending on the layer where the drug is incorporated. Thus, systems with an immediate bacteriostatic effect, as well as systems with a potential long term antimicrobial effect, are obtained. Growth inhibition and adhesion assays demonstrate the fast bactericidal effect of samples with CHX loaded in its outer layers.     

Nanostructure development in polystyrene‐b‐polybutadiene‐b‐poly(methyl methacrylate) (SBM) thin films by atomic force microscopy: Effect of copolymer composition and solvent

Surface morphology development for SBM triblock copolymer thin films has been studied by atomic force microscopy. The effect of copolymer composition and solvent on the final morphology has been investigated. Obtained results indicated that depending on the block ratio (symmetric or asymmetric with minority middle block) and solvent, lamellar, hexagonal, cylindrical, or spheres in lamellae (ls)‐type morphologies can be achieved at film surfaces. The influence of the interaction parameters among blocks and solvents and cohesive energy values of block pairs on the final morphology has been proved. POLYM. ENG. SCI., 58:422–429, 2018. © 2017 Society of Plastics Engineers     

Collision Avoidance Based Neighbor Discovery in Ad Hoc Wireless Networks

Wireless Personal Communications - Neighbor discovery is an important first step after the deployment of ad hoc wireless networks since they are a type of network that do not provide a...     

Design and evaluation of ECO: an augmentative and alternative communication tool

Universal Access in the Information Society - Current technology provides new challenges to improve skills on people with special necessities. In fact, persons with communications needs can take...     

Emulsion polymerization: particle growth kinetics

An attempt to develop a predictive and manageable mathematical model for particle growth in emulsion homopolymerization was carried out by fitting the time evolution of the conversion in the chemically initiated seeded emulsion polymerization of styrene carried out under a wide range of experimental conditions with models of different complexity. Model discrimination based on the best fitting of the experimental data was carried out. No advantage was gained by increasing the complexity of the mathematical model. The dependence of the radical entry and exit rate parameters on the particle size was used to elucidate between the different mechanisms proposed for these processes.