Formulating Nonionic Detergents via the Integrated Free Energy Model

This work explores the optimum detergency conditions of alkyl ethoxylate (C_XEO_Y) surfactants with the integrated free energy model (IFEM). IFEM is a molecular thermodynamic model that calculates the free energy of formation of oil-swollen spherical micelles, with a core solubilization radius Ro, using surfactants from empty (oil-free) micelles and oil molecules from a continuous oil phase. The described geometry allows for rapid calculations, using a personal laptop (3.4 GHz processor), where each solubilization energy profile (free energy vs. Ro curve) can be solved in 5 min or less. While previous work showed quantitative agreement between IFEM predictions and experimental solubilization of alkanes in C_XEO_Y micelles, this work explores the possibility of using IFEM as a tool in surfactant selection. Experimental work has shown that detergency improved when operating near the phase inversion temperature (PIT) of the surfactant-hexadecane system. The IFEM simulations in this work show, for the first time, that IFEM can be used to predict the PIT of surfactant-oil systems, and that the surfactants selected via this method are consistent with the selection guided by experimental observations.     

Kinetics of the xylitol crystallization in hydro-alcoholic solution

Nývlt method was used to determine the kinetic parameters of commercial xylitol in ethanol:water (50:50 %w/w) solution by batch cooling crystallization. The kinetic exponents (n, g and m) and the system kinetic constant (B_N) were determined. Model experiments were carried out in order to verify the combined effects of saturation temperatures (40, 50 and 60 °C) and cooling rates (0.10, 0.25 and 0.50 °C/min) on these parameters. The fitting between experimental and calculated crystal sizes has 11.30% mean deviation.     

Preparation,characterization and single cell testing of new ionic conducting polymers for fuel cell applications

In this work, heterogeneous sulfonation and both, structural and electrical characterization of a mixture composed on block copolymer ionomers (HSBS and EPDM) and commercial silica, are studied. The incorporation of sulfonic groups was checked by infrared spectroscopy (FTIR-ATR). Microstructure was studied by means of dynamic mechanical analysis (DMA). Also, water uptake and methanol crossover were determined, and the results were compared with those of Nafion^® 117. Electrical behavior was recorded by means of electrochemical impedance spectroscopy (EIS) at different hydration times. Results show that sulfonation of the styrene rings has effectively occurred. Conductivity values are similar to Nafion and they improve with hydration time. Methanol crossover is lower than in Nafion.     

The effects of scientific regional opportunities in science-technology flows: Evidence from scientific literature in firms patent data

Relevant scientific literature has demonstrated that in spaces of smaller scale than the national, the availability of scientific knowledge is also relevant for generating spillover effects that benefit the industrial sector. The proliferation of such literature consistently stressing the importance of physical proximity for the two-way flow of knowledge and for the development and fostering of innovation, together with the high degree of self-government of the Spanish regions (which have the competence to develop their own R&D policies), all suggest that the relationships between the scientific community and the industrial sector may be closer and more productive in the regions where the scientific potential is more relevant, in comparison with other regions. The basic objective of this article is to test for the possible differential effects of a favourable scientific environment on science-technology relationships, and more specifically, to determine if the considerable regional resources directed towards scientific research in local universities are being translated into economic results for industry, by way of better utilisation of scientific knowledge to enable companies to generate more and better innovations in processes and products. The methodology that we employ relates the scientific citations in patent documents - as a basic indicator of these science-technology flows- with various indicators of resources and results of academic research that reflect the scientific research environment. With caution, and recognising the limitations inherent in the NPC (non patent citation) methodology, different econometric specifications permit the conclusion to be drawn that companies of those regions with a more favourable scientific environment make greater use of scientific knowledge. Received: September 2003/Accepted: October 2004 The authors are members of Eco-21 Research Project. Centra Foundation (Junta de Andalucía). We are grateful for the useful comments on an earlier draft of this paper that were provided by three anonymous referees. This research has been granted by the Ministry of Science and Technology (SEC 2001–3030).     

Preparation and characterization of hybrid thiol‐ene/epoxy UV–thermal dual‐cured systems

Hybrid thiol‐ene/epoxy coatings were prepared by combining thiol‐ene photo‐curable formulations with epoxy monomers, through a dual UV–thermal curing process. An increase in glass transition temperature and in storage modulus was observed for the hybrid thiol‐ene/epoxy coatings when compared with the pristine thiol‐ene UV‐cured system. Also, the bisphenol A moieties introduced into the hybrid networks during the dual‐curing process induced an increase in thermal stability of the cured materials. It has been demonstrated that the addition of epoxy monomer to the thiol‐ene photo‐curable system is a good strategy to follow in order to improve the final properties of thiol‐ene‐based coatings leading to a wide range of possible applications for the hybrid materials. Copyright © 2010 Society of Chemical Industry     

Focal Shift in Lenslike Media with Gain or Loss

Abstract

Focal shift in lenslike systems having loss or gain is evaluated. The results obtained show a shift in the geometrical focus with respect to the lossless case. The best focus is determined for uniform plane and Gaussian illumination.     

Evolution of the properties of a poly(l‐lactic acid) scaffold with double porosity during in vitro degradation in a phosphate‐buffered saline solution

A poly(l ‐lactic acid) scaffold prepared by a combination of freeze‐extraction and porogen‐leaching methods was submitted to static degradation in a phosphate‐buffered saline solution at pH 7.4 and 37°C for up to 12 months. After 6 months of degradation, the scaffold maintained its integrity, although noticeable changes in its permeability and pore size were recorded. After 12 months, scanning electron microscopy pictures showed that most of the trabeculae were broken, and the sample disaggregated under minimum loading. Neither weight loss nor crystallinity changes in the first heating calorimetric scan were observed during the degradation experiment. However, after 12 months, a rise in the crystallinity from 13 to 38% and a drop in the glass‐transition temperature from 58 to 54°C were measured in the second heating scan. The onset of thermal degradation moved from 300 to 210°C after 12 months. Although the elastic modulus suffered only a very slight reduction with degradation time, the aggregate modulus decreased 44% after 6 months. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40956.     

Tomographic method for measurement of the gradient refractive index of the crystalline lens. II. The rotationally symmetrical lens

In the first part of this paper we presented a tomographic method to reconstruct the refractive index profile of spherically symmetrical lenses. Here we perform the generalization to lenses that are rotationally symmetrical around the optical axis, as is the ideal human lens. Analysis of the accuracy and versatility of this method is carried out by performing numerical simulations in which different magnitudes of experimental errors and two extreme case scenarios for the likely shape of the refractive index distribution of the human lens are considered. Finally, experimental results for a porcine lens are shown. Conceptually simple and computationally swift, this method could prove to be a valuable tool for the accurate retrieval of the gradient index of a broad spectrum of rotationally symmetrical crystalline lenses.