Crystal growth as an excitable medium

Crystal growth has been widely studied for many years, and, since the pioneering work of Burton, Cabrera and Frank, spirals and target patterns on the crystal surface have been understood as forms of tangential crystal growth mediated by defects and by two-dimensional nucleation. Similar spirals and target patterns are ubiquitous in physical systems describable as excitable media. Here, we demonstrate that this is not merely a superficial resemblance, that the physics of crystal growth can be set within the framework of an excitable medium, and that appreciating this correspondence may prove useful to both fields. Apart from solid crystals, we discuss how our model applies to the biomaterial nacre, formed by layer growth of a biological liquid crystal.     

Advances in Artificial Neural Networks and Computational Intelligence

Neural Processing Letters -     

Improvement and Validation of Phytate Determination in Edible Seeds and Derived Products,as Mineral Complexing Activity

The analysis of phytates, as antinutrients that naturally occur in edible seeds, is important due to its interaction with certain minerals (Ca, Mg, Zn, Fe) essential for health, especially for children or other groups at risk of deficiency diseases. Although several analytical methods for phytates use complex techniques, complexometric methods are recently applied since they provide the knowledge of real mineral complexing activity of different phytates in foods, which is of great relevance for nutritional studies. A reliable method for phytate quantification in terms of cation binding activity has been optimized, based on previous complexometric methods, with the improvement of quantification through calibration with standards instead of estimation through equations. The methodology was optimized for different matrices of seeds and seed-derived food products, including infant foods, and it was validated according to AOAC standards to assess reliability. Due to the presence of different phytate forms in foods, and the different ability of complexation of each one, the expression of results of phytates as phytic acid equivalents (PAE) is proposed. With this methodology, phytates were found in all the samples analyzed, showing a higher amount in seeds (4029 mg PAE/100 g in dehulled hemp seed) than in infant foods (231 mg PAE/100 g in rice formula). From the validation protocol, the method showed good linearity, accuracy, and precision for food samples over 80 mg PAE/100 g, not requiring high-cost equipment, and providing high reliability and practical applicability for routine laboratories, with the purpose of monitoring of food quality.     

Hybrid organic–inorganic macromolecular photoinitiator system for visible-light photopolymerization

Hybrid organic–inorganic macrophotoinitiator bearing pendant tertiary amine groups (OI-AH) was prepared by hydrolytic condensation of a silane containing amino groups. The macromolecular amino-functionalized photoinitiator was used in combination with camphorquinone (CQ) for visible-light photo-polymerization. The OI-AH was incorporated into methacrylate resins at loadings between 1 and 10 wt.%. The photodecomposition of the CQ/OI-AH in methacrylate monomers under visible light irradiation (λ = 470 nm) was examined. The photolysis products of CQ/OI-AH were transparent at the irradiating wavelengths; consequently, the consumption of the CQ is accompanied by increased light intensity in the underlying lays. The clean and rapid photobleaching of CQ in combination with OI-AH makes this photoinitiator system very attractive for polymerization of thick sections. The evolution of monomer conversion versus irradiation time showed that the OI-AH is an efficient co-initiator of CQ because a fast reaction and high conversion of methacrylate groups result after 60 s irradiation with a LED source of 140 mW.     

On complete fuzzy preorders and their characterizations

In the context of crisp or classical relations, one may find several alternative characterizations of the concept of a total preorder. In this contribution, we first discuss the way of translating those characterizations to the framework of fuzzy relations. Those new properties depend on t-norms. We focus on two important families of t-norms, namely those that do not admit zero divisors and those that are rotation invariant. For these families, we study whether or not the properties shown for fuzzy relations lead to characterizations of complete fuzzy preorders. Special attention is paid to the minimum operator, which shows the best behaviour in preserving most of the characterizations known for crisp relations.     

Photothermal,Structural, and Microstructural Characterization of SAE4320H Automotive Steel

SAE4320H steel was characterized by photothermal radiometry spectroscopy, scanning electron microscopy, x-ray diffraction, and Vickers microhardness, to study metallurgical property changes as a result of the annealing heat treatment. Photothermal radiometry (PTR) images of hot forged and annealed SAE4320H steel were obtained to study the thermal changes, as a consequence of metallurgical microstructure changes that were produced by the heat treatment conditions. X-ray diffraction showed that the annealing process improves the crystalline quality of the SAE4320H steel and releases of any thermal stress. Widmanstatten microstructure was identified as a typical structure after the forging process. The Widmanstatten is a metallographic microstructure transformation to ferrite and pearlite which affected SAE4320H steel hardness and thermal properties. Vickers test showed that the hardness decreases as a result of the annealing process. A positive correlation between Vickers microhardness and PTR amplitude images was found, indicating that the annealing process increases the PTR signal. This methodology allows the determination of the changes in the Vickers microhardness from a non-contact and remote method as in PTR.     

Control of Several Emissions during Olive Pomace Thermal Degradation

Biomass plays an important role as an energy source, being an interesting alternative to fossil fuels due to its environment-friendly and sustainable characteristics. However, due to the exposure of customers to emissions during biomass heating, evolved pollutants should be taken into account and controlled. Changing raw materials or mixing them with another less pollutant biomass could be a suitable step to reduce pollution. This work studied the thermal behaviour of olive pomace, pyrenean oak and their blends under combustion using thermogravimetric analysis. It was possible to monitor the emissions released during the process by coupling mass spectrometry analysis. The experiments were carried out under non-isothermal conditions at the temperature range 25–750 °C and a heating rate of 20 °C·min⁻¹. The following species were analysed: aromatic compounds (benzene and toluene), sulphur emissions (sulphur dioxide), 1,4-dioxin, hydrochloric acid, carbon dioxide and nitrogen oxides. The results indicated that pollutants were mainly evolved in two different stages, which are related to the thermal degradation steps. Thus, depending on the pollutant and raw material composition, different emission profiles were observed. Furthermore, intensity of the emission profiles was related, in some cases, to the composition of the precursor.     

An interval extension based on occurrence grouping

In interval arithmetics, special care has been brought to the definition of interval extension functions that compute narrow interval images. In particular, when a function f is monotonic w.r.t. a variable in a given domain, it is well-known that the monotonicity-based interval extension of f computes a sharper image than the natural interval extension does. This paper presents a so-called “occurrence grouping” interval extension [f] _og of a function f. When f is not monotonic w.r.t. a variable x in a given domain, we try to transform f into a new function f ^og that is monotonic w.r.t. two subsets x _a and x _b of the occurrences of x: f ^og is increasing w.r.t. x _a and decreasing w.r.t. x _b . [f] _og is the interval extension by monotonicity of f ^og and produces a sharper interval image than the natural extension does. For finding a good occurrence grouping, we propose a linear program and an algorithm that minimize a Taylor-based over-estimate of the image diameter of [f] _og . Experiments show the benefits of this new interval extension for solving systems of nonlinear equations.