Organometallic–Inorganic Conjugated Unsymmetrical Schiff-Base Hybrids. Synthesis,Characterization, Electrochemistry and X-ray Crystal Structures of Functionalized Trinuclear Iron–Nickel–Ruthenium Dipolar Chromophores

The synthesis of neutral dinuclear iron–nickel unsymmetrical Schiff base complexes 3 and 4 was achieved via a template reaction involving equimolar amounts of alkyl or aryl “half-unit” precursors, respectively, Fc–C(O)CH=C(CH₃)N(H)R (1: R = CH₂CH₂NH₂; 2: R = o-C₆H₄NH₂; Fc = CpFe(η⁵-C₅H₄); Cp = η⁵-C₅H₅), 5-bromosalicylaldehyde and nickel(II) acetate tetrahydrate in a refluxing CH₂Cl₂/MeOH (1:1) mixture. The ionic trinuclear unsymmetrical complex 5 was prepared by reacting its dinuclear precursor 3 with the arenophile source, [Cp*Ru(NCCH₃)₃]PF₆ (Cp* = η⁵-C₅(CH₃)₅), in refluxing CH₂Cl₂ for 2 h, whereas the trinuclear species 6 was formed upon regioselective π-complexation of the 5-bromosalicylidene ring of 4 by [Cp*Ru]⁺ at room temperature overnight. All the new compounds were adequately characterized by analytical and spectroscopic techniques and, in addition, the crystal and molecular structures of the “half-unit” 1, the binuclear complex 4 and its hemisolvate adduct 4 · 0.5CH₃OH, the trinuclear Schiff base compound 5 · 2(CH₃)₂CO, and the mixed sandwich metalloligand 7 have been determined by X-ray crystallography. Both organometallic–inorganic hybrids 5 and 6 contain the neutral electron-releasing ferrocenyl group, and the cationic electron-withdrawing ruthenium mixed sandwich, linked through the unsymmetrical tetradentate Schiff base complex {Ni(ONNO)}. UV–vis, ¹H and ¹³C NMR as well as electrochemical data clearly indicate a mutual donor–acceptor electronic influence between the organometallic termini. Furthermore, X-ray crystal structure analysis of 5 · 2(CH₃)₂CO reveals the partial delocalization of bonding electron density throughout the dinucleating nickel Schiff base ligand. Dedicated to Prof. Didier Astruc, a true friend, an outstanding lecturer and scientist, in honor of his pioneering research efforts and accomplishments in the fields of organometallic chemistry, dendrimers and their applications in nanocatalysis.     

Forecasting electricity prices and their volatilities using Unobserved Components

The liberalization of electricity markets more than ten years ago in the vast majority of developed countries has introduced the need of modelling and forecasting electricity prices and volatilities, both in the short and long term.Thus, there is a need of providing methodology that is able to deal with the most important features of electricity price series, which are well known for presenting not only structure in conditional mean but also time-varying conditional variances.In this work we propose a new model, which allows to extract conditionally heteroskedastic common factors from the vector of electricity prices. These common factors are jointly estimated as well as their relationship with the original vector of series, and the dynamics affecting both their conditional mean and variance. The estimation of the model is carried out under the state-space formulation.The new model proposed is applied to extract seasonal common dynamic factors as well as common volatility factors for electricity prices and the estimation results are used to forecast electricity prices and their volatilities in the Spanish zone of the Iberian Market.Several simplified/alternative models are also considered as benchmarks to illustrate that the proposed approach is superior to all of them in terms of explanatory and predictive power.     

Recovery of Aromatic Aglycones from Grape Pomace Winemaking By-Products by Using Liquid-Liquid and Pressurized-Liquid Extraction

The potential of winemaking grape pomace by-products as a source of glycosidic aroma precursors that under enzymatic hydrolysis might release aroma compounds has been evaluated. Two different extraction methodologies, liquid–liquid and pressurized liquid extraction (LLE and PLE) were employed. Solid phase extraction (SPE)-GC-MS analysis of the hydrolyzed LLE glycosidic extract revealed 22 aroma compounds belonging to different chemical families (terpenes, C13 norisoprenoids, vanillines, etc.). Response surface methodology was employed to study the effect of the most significant PLE experimental variables (temperature and solvent composition) on the extraction of aromatic aglycones. The parameters of the model were estimated by multiple linear regressions. Most of the aroma compounds showed an adequate fit to the calculated model (18 compounds from 22 with R ²?>?0.8). The application of the optimized PLE conditions (50 % of ethanol in the hydroalcoholic solution) and 90 °C showed higher extraction yield of aglycones when comparing with the extraction yield obtained by LLE.     

Micro-PIXE investigation of bean seeds to assist micronutrient biofortification

This study compares the distribution and concentrations of micro- and macronutrients in different bean cultivars with the aim of optimizing the biofortification, a sustainable approach towards improving dietary quality. Micro-PIXE was used to reveal the distribution of Fe, Zn, Mn, Ca, P, S in seeds of common beans (Phaseolus vulgaris) and runner beans (Phaseolus coccineus). Average concentrations of elements in different tissues were obtained using ICP-AES. The highest concentrations of Zn in the studied beans were found in the embryonic axis, but an increased concentration of this element was also detected in the provascular bundles of the cotyledons. The first layer of cells surrounding provascular bundles accumulated high concentrations of Fe, while the next cell layer had an increased concentration of Mn. The analysis showed that the provascular bundles and the first cell layers surrounding them could have a significant role in the storage of important seed micronutrients - Zn, Fe, and Mn. This information has important implications for molecular biology studies aimed at seed biofortification.     

Inverse analysis with integral transformed temperature fields: Identification of thermophysical properties in heterogeneous media

The objective of this work is to introduce the use of integral transformed temperature measured data for the solution of inverse heat transfer problems, instead of the common local transient temperature measurements. The proposed approach is capable of significantly compressing the measured data through the integral transformation, without losing the information contained in the measurements and required for the solution of the inverse problem. The data compression is of special interest for modern measurement techniques, such as the infrared thermography, that allows for fine spatial resolutions and large frequencies, possibly resulting on a very large amount of measured data. In order to critically address the use of integral transformed measurements, we examine in this paper the simultaneous estimation of spatially variable thermal conductivity and thermal diffusivity in one-dimensional heat conduction within heterogeneous media. The direct problem solution is analytically obtained via integral transforms and the related eigenvalue problem is solved by the Generalized Integral Transform Technique (GITT). The inverse problem is handled with Bayesian inference by employing a Markov Chain Monte Carlo (MCMC) method. The unknown functions appearing in the formulation are expanded in terms of eigenfunctions as well, so that the unknown parameters become the corresponding series coefficients. Such projection of the functions in an infinite dimensional space onto a parametric space of finite dimension also permits that several quantities appearing in the solution of the direct problem be analytically computed. Simulated measurements are used in the inverse analysis; they are assumed to be additive, uncorrelated, normally distributed, with zero means and known covariances. Both Gaussian and non-informative uniform distributions are used as priors for demonstrating the robustness of the estimation procedure.     

Characterization of piñon seed (Araucaria araucana (Mol) K. Koch) and the isolated starch from the seed

Araucaria (Araucaria araucana) is a conifer tree, endemic of Chile. The seed of this tree, named piñon are composed principally of starch. In this work, piñon seeds and the starch isolated from them were evaluated. The piñon seeds are composed of starch (64%), dietary fibre (25%), total sugar (7%) and very low concentrations of phenolic compounds, lipids, proteins and crude fibre. The process performed to isolate the starch from piñon was simple and easy to realize at laboratory scale, with a yield of 36%. Starch represents a 77% of the isolated starch. The amylose content was 42%. Lipids, protein and crude fibre were very low. The starch hydration properties increased with the temperature. In the 6% suspension of starch, viscosity increases during the cooling period. The starch granules of piñon were small and round shaped. The aspects evaluated in this research, suggests that piñon seeds can be considered an interesting new starch source for the food industry.     

Effects of the flaxseed oil on the fatty acid composition of tilapia heads

The objective of this study was to evaluate the effects of adding flaxseed oil (FO) to feed on the incorporation of n‐3 PUFA in tilapia heads. Tilapia were given diets with increasing levels of FO (0.00, 1.25, 2.50, 3.75 and 5.00% for treatments A, B, C, D and E, respectively), as a source of LNA for 150 days. The proximate composition of the heads indicated high nutritional value and 40 FA (fatty acids) common to all treatments were identified in total lipids. Intake of LNA caused storage of LNA and sequential desaturation‐elongation to eicosapentaenoic acid (EPA) and DHA. With increasing levels of FO in the diet, the content of LNA in tilapia heads increased (1.7 and 14.0% for diets A and E, respectively), as well as the contents of EPA (0.1 and 0.9% for diets A and E, respectively) and DHA (0.5 and 1.8% for diets A and E, respectively). Adding FO to tilapia feed markedly increased the total content of n‐3 PUFA (3.0 and 21.1% for diets A and E, respectively), decreased the total content of n‐6 PUFA (41.3 and 24.9% for diets A and E, respectively), and consequently resulted in a decrease in the n‐6/n‐3 ratio (13.8 and 1.2 for diets A and E, respectively). Therefore, feeding tilapia with FO is a good way of valorizing this part of the fish by creating a valuable nutritional food source.     

Prediction of fatty acid composition using a NIRS fibre optics probe at two different locations of ham subcutaneous fat

NIR technology was used to analyze the fatty acid composition of fat tissue from conjugated linoleic acid fed pigs by direct application of a fibre optics probe on two different locations of subcutaneous fat. One hundred and fifty-three pigs were fed three different diets and the fatty acid profile of subcutaneous fat from Gluteus medius was analyzed using gas chromatography and FT-NIR in a longitudinal and transversal cut. Spectra were acquired using a Bruker Optics Matrix-F duplex spectrometer equipped with a fibre optics probe (IN-268-2). Total saturated, monounsaturated and polyunsaturated together as well as oleic and stearic fatty acids were predicted accurately (R² > 0.70), myristic, and linoleic fatty acids were predicted with lower accuracy (0.60 < R² < 0.70), while palmitic, asclepic and α-linolenic fatty acids were poorly predicted (R² < 0.60). Results indicated that NIR technology has potential as a rapid tool to discriminate carcasses from animals fed diets with different fatty acid composition by a direct measurement on the fat from the ham.     

The sanitizing action of essential oil-based solutions against Salmonella enterica serotype Enteritidis S64 biofilm formation on AISI 304 stainless steel

Bacterial adhesion and biofilm formation by Salmonella enterica serovar Enteritidis is a serious concern in the food processing industry; organism persistence in biofilms represents a continual source of contamination. Due to unsuccessful disinfection processes and emerging resistance, conventional control methods are rapidly becoming ineffective, necessitating the development of new control strategies. The following study evaluated the anti-biofilm effect of disinfectant solutions formulated with essential oils (EOs) of peppermint (Mentha piperita) and lemongrass (Cymbopogon citratus) against biofilm formation by S. enterica serotype Enteritidis S64 on stainless steel surface AISI 304 (#4) after 10, 20 and 40 min of contact. A minimum inhibitory concentration (MIC) of 7.8 μL/mL was found for both EOs and disinfectant solutions were formulated based on these MIC values. Ten minutes of sanitizing solution contact significantly reduced (p ≤ 0.05) adhered bacterial populations for both EOs tested. After 20 and 40 min of treatment, cell counts were not detected. Thus, M. piperita and C. citratus EOs can be considered convenient, quality alternatives to the application of conventional sanitizing agents in the food industry; further, use of these EOs addresses the increasing consumer demand for natural products.