Harnessing Selectivity and Sensitivity in Ion Sensing via Supramolecular Recognition: A 3D Hybrid Gold Nanoparticle Network Chemiresistor

The monitoring of K⁺ in saliva, blood, urine, or sweat represents a future powerful alternative diagnostic tool to prevent various diseases. However, several K⁺ sensors are unable to meet the requirements for the development of point-of-care (POC) sensors. To tackle this grand-challenge, the fabrication of chemiresistors (CRs) based on 3D networks of Au nanoparticles covalently bridged by ad-hoc supramolecular receptors for K⁺, namely dithiomethylene dibenzo-18-crown-6 ether is reported here. A multi-technique characterization allows optimizing a new protocol for fabricating high-performing CRs for real-time monitoring of K⁺ in complex aqueous environments. The sensor shows exceptional figures of merit: i) linear sensitivity in the 10^–3 to 10^–6 m concentration range; ii) high selectivity to K⁺ in presence of interfering cations (Na⁺, Ca²⁺, and Mg²⁺); iii) high shelf-life stability ( > 45 days); iv) reversibility of K⁺ binding and release; v) successful device integration into microfluidic systems for real-time monitoring; vi) fast response and recovery times ( < 18 s), and v) K⁺ detection in artificial saliva. All these characteristics make the supramolecular CRs a potential tool for future applications as POC devices, especially for health monitoring where the determination of K⁺ in saliva is pivotal for the early diagnosis of diseases.     

Separation and spectroscopic analysis of the aromatic fraction of oils from lignite depolymerization

The aromatic fraction of oils obtained by catalytic depolymerization of a Spanish subbituminous coal has been separated by means of liquid chromatography on partially deactivated alumina into six subfractions, which were studied by i.r. and ¹H n.m.r. spectroscopy. The results indicate hydroaromatic structures with a low degree of condensation, with one to three aromatic nuclei on average, short chain alkyl substituents and significant amounts of -OH and aromatic ether groups.     

One-to-One Coordination Algorithm for Decentralized Area Partition in Surveillance Missions with a Team of Aerial Robots

This paper presents a decentralized algorithm for area partition in surveillance missions that ensures information propagation among all the robots in the team. The robots have short communication ranges compared to the size of the area to be covered, so a distributed one-to-one coordination schema has been adopted. The goal of the team is to minimize the elapsed time between two consecutive observations of any point in the area. A grid-shape area partition strategy has been designed to guarantee that the information gathered by any robot is shared among all the members of the team. The whole proposed decentralized strategy has been simulated in an urban scenario to confirm that fulfils all the goals and requirements and has been also compared to other strategies.     

A Multiscale-Based Approach to Understand Dendrite Deflection in Continuously Cast Steel Slab Samples

Dendrite bending angle measurements were conducted along two different directions on four steel slab samples collected from a conventional caster. The primary dendrites growing at the slab surface showed a transition in their growth direction as the distance from the surface increased. Numerical fluid flow simulation showed changes in the flow directions that might have caused the change in the growth direction. The bending angle measurements were also correlated with the casting process parameters. Thereafter, a multiscale approach was adopted to predict the dendrite deflection angles by correlating the macro-scale flow profile with the micro-scale bending angle formulation and subsequently corroborated with the industrial scale measurements.

     

New Trends in Food Allergens Detection: Toward Biosensing Strategies

Food allergens are a real threat to sensitized individuals. Although food labeling is crucial to provide information to consumers with food allergies, accidental exposure to allergenic proteins may result from undeclared allergenic substances by means of food adulteration, fraud or uncontrolled cross-contamination. Allergens detection in foodstuffs can be a very hard task, due to their presence usually in trace amounts, together with the natural interference of the matrix. Methods for allergens analysis can be mainly divided in two large groups: the immunological assays and the DNA-based ones. Mass spectrometry has also been used as a confirmatory tool. Recently, biosensors appeared as innovative, sensitive, selective, environmentally friendly, cheaper and fast techniques (especially when automated and/or miniaturized), able to effectively replace the classical methodologies. In this review, we present the advances in the field of food allergens detection toward the biosensing strategies and discuss the challenges and future perspectives of this technology.     

Impact of Front-Haul Delays in Non-ideal Cloud Radio Access Networks

Wireless Personal Communications - The principle of Cloud Radio Access Network (C-RAN) is the split of traditional base stations into Radio Remote Units (RRU) as low-cost wireless access points,...     

A Unified Mechanism for the Formation of Oscillation Marks

Oscillation marks (OMs) are regular, transverse indentations formed on the surface of continuously cast (CC) steel products. OMs are widely considered defects because these are associated with segregation and transverse cracking. A variety of mechanisms for their formation has been proposed (e.g., overflow, folding, and meniscus freezing), whereas different mark types have also been described (e.g., folded, hooks, and depressions). The current work uses numerical modeling to formulate a unified theory for the onset of OMs. The initial formation mechanism is demonstrated to be caused by fluctuations in the metal and slag flow near the meniscus, which in turn causes thermal fluctuations and successive thickening and thinning of the shell, matching the thermal fluctuations observed experimentally in a mold simulator. This multiphysics modeling of the transient shell growth and explicit prediction of OMs morphology was possible for the first time through a model for heat transfer, fluid flow, and solidification coupled with mold oscillation, including the slag phase. Strategies for reducing OMs in the industrial practice fit with the proposed mechanism. Furthermore, the model provides quantitative results regarding the influence of slag infiltration on shell solidification and OM morphology. Control of the precise moment when infiltration occurs during the cycle could lead to enhanced mold powder consumption and decreased OM depth, thereby reducing the probability for transverse cracking and related casting problems.     

The accessibility to employment offices in the Spanish labour market*

This paper focuses on the differences in the levels of accessibility to public employment offices in the Spanish municipalities. Hence the main purpose is to evaluate the role of the public employment services in local labour markets by considering the physical distance to employment offices and the spatial structure of their catchment areas. First, we propose an accessibility measure and, second, we estimate a spatial model and test whether a higher accessibility to employment offices could contribute to reduce local unemployment rates. The results suggest that policy‐makers should strive to improve the accessibility to employment offices so that adequate assistance to find suitable employment may be ensured to every jobseeker. Resumen Este artículo se centra en las diferencias en los niveles de accesibilidad a las oficinas públicas de empleo en los municipios españoles. El objetivo principal es por tanto evaluar el papel de los servicios públicos de empleo en los mercados laborales locales, en función de la distancia física a las oficinas de empleo y la estructura espacial de sus zonas de influencia. Primero, se propone una medida de accesibilidad y, a continuación, se estima un modelo espacial y se comprueba si una mayor accesibilidad a las oficinas de empleo podría contribuir a reducir las tasas de desempleo local. Los resultados sugieren que los responsables de formular políticas deberían esforzarse por mejorar la accesibilidad a las oficinas de empleo, a fin de poder asegurar a cada demandante de empleo la ayuda apropiada para que logre encontrar un empleo adecuado.      

Variability in the intercomparison of food carotenoid content data: A user's point of view

The availability of reliable information on food composition is essential both for the evaluation of diet and for nutritional research to relate diet to health or disease. In this article, we compare the total and individual carotenoid contents and the retinol equivalents in fruits and vegetables reported in several food composition tables and HPLC studies. The impact of the variability in carotenoid intake was evaluated on the basis of Spanish National Consumption Statistics and on the values for a standard diet. We identify, from a user's point of view, errors concerning identification of the items and the terms used to refer to the compounds. Food composition tables overestimate (by 2 to 48%) the retinol equivalent intake, whereas they underestimate (by 30 to 50%) the total carotenoid intake according to HPLC data. We study the effect of these main sources of error, their impact on dietary assessment and on the classification of relevant contributors, and the possible consequences with respect to proper diet in terms of nutritional assessment and epidemiological studies. Given the different dietary habits among populations and the fact that certain items may be over‐ or underestimated in databases, the use of a single database may be misleading as to the rate of carotenoid consumption and the “true” nutrient intake in a given population, thus weakening the reliability of the study and resulting in erroneous conclusions.     

Insights into the metabolism and microbial biotransformation of dietary flavan-3-ols and the bioactivity of their metabolites

Flavan-3-ols, occurring in monomeric, as well as in oligomeric and polymeric forms (also known as condensed tannins or proanthocyanidins), are among the most abundant and bioactive dietary polyphenols, but their in vivo health effects in humans may be limited because of their recognition as xenobiotics. Bioavailability of flavan-3-ols is largely influenced by their degree of polymerization; while monomers are readily absorbed in the small intestine, oligomers and polymers need to be biotransformed by the colonic microbiota before absorption. Therefore, phenolic metabolites, rather than the original high molecular weight compounds found in foods, may be responsible for the health effects derived from flavan-3-ol consumption. Flavan-3-ol phenolic metabolites differ in structure, amount and excretion site. Phase II or tissular metabolites derived from the small intestine and hepatic metabolism are presented as conjugated derivatives (glucuronic acid or sulfate esters, methyl ether, or their combined forms) of monomeric flavan-3-ols and are preferentially eliminated in the bile, whereas microbial metabolites are rather simple conjugated lactones and phenolic acids that are largely excreted in urine. Although the colon is seen as an important organ for the metabolism of flavan-3-ols, the microbial catabolic pathways of these compounds are still under consideration, partly due to the lack of identification of bacteria with such capacity. Studies performed with synthesized or isolated phase II conjugated metabolites have revealed that they could have an effect beyond their antioxidant properties, by interacting with signalling pathways implicated in important processes involved in the development of diseases, among other bioactivities. However, the biological properties of microbe-derived metabolites in their actual conjugated forms remain largely unknown. Currently, there is an increasing interest in their effects on intestinal infections, inflammatory intestinal diseases and overall gut health. The present review will give an insight into the metabolism and microbial biotransformation of flavan-3-ols, including tentative catabolic pathways and aspects related to the identification of bacteria with the ability to catabolize these kinds of polyphenols. Also, the in vitro bioactivities of phase II and microbial phenolic metabolites will be covered in detail.