The rapid growth of the biodiesel industry has led to a large surplus of its major byproduct, i.e. glycerol, for which new applications need to be found. Research efforts in this area have focused ...mainly on the development of processes for converting glycerol into value-added chemicals and its reforming for hydrogen production, but recently, in line with the increasing interest in the use of alternative greener solvents, an innovative way to revalorize glycerol and some of its derivatives has seen the light, i.e. their use as environmentally friendly reaction media for synthetic organic chemistry. The aim of the present Feature Article is to provide a comprehensive overview on the developments reached in this field.
The main objective of this work is to determine which kind of acidic sites, Brønsted (BAS) or Lewis (LAS), are more active and stable in the glycerol acetalization to solketal by means of ...Raman-monitoring. For this purpose, the mesoporous cellular foams (MCFs) were modified to obtain materials containing exclusively BAS occurring in different number and strength (samples MP-MCF (MP = (3-mercaptopropyl)trimethoxysilane) and CS-MCF (CS = 2-(4-chlorosulfonylphenyl)ethyltrimethoxysilane)) or the material containing exclusively LAS (NbMCF). Moreover, the materials containing both types of centers in different ratios (MoMCF and TaMCF) were also studied. Real-time Raman monitoring of the catalytic reaction allowed us to observe not only changes in substrates concentration and product yield but also the transformation of acetone–glycerol adduct (O···CO vibrations) formed in the presence of a catalyst. The activity of the catalysts containing BAS depends on the number and strength of these centers, and the best performance was observed for CS-MCF. The maximum of solketal yield and the equilibrium state were achieved after 2 min from the start of the Raman monitoring. NbMCF containing exclusively LAS exhibited both the lowest conversion of glycerol and stability. The role of different recycling treatments was probed.
This paper studies static and dynamic decentralized versions of the search model known as cellular genetic algorithm (cGA), in which individuals are located in a specific topology and interact only ...with their neighbors. Making changes in the shape of such topology or in the neighborhood may give birth to a high number of algorithmic variants. We perform these changes in a methodological way by tuning the concept of ratio. Since the relationship (ratio) between the topology and the neighborhood shape defines the search selection pressure, we propose to analyze in depth the influence of this ratio on the exploration/exploitation tradeoff. As we will see, it is difficult to decide which ratio is best suited for a given problem. Therefore, we introduce a preprogrammed change of this ratio during the evolution as a possible additional improvement that removes the need of specifying a single ratio. A later refinement will lead us to the first adaptive dynamic kind of cellular models to our knowledge. We conclude that these dynamic cGAs have the most desirable behavior among all the evaluated ones in terms of efficiency and accuracy; we validate our results on a set of seven different problems of considerable complexity in order to better sustain our conclusions.
•Motion magnification enhances DIC results in high frequency mode shapes.•No shape aberration occurs during magnification.•Extreme excitation level is not required to characterise high mode shapes ...with DIC.•The combination provides graphical and quantitative information of mode shapes.•Full-field measurements from magnified images improve comparison with FEM models.
High speed video cameras provide valuable information in dynamic events. Mechanical characterisation has been improved by the interpretation of the behaviour in slow-motion visualisations. In modal analysis, videos contribute to the evaluation of mode shapes but, generally, the motion is too subtle to be interpreted. In latest years, image treatment algorithms have been developed to generate a magnified version of the motion that could be interpreted by naked eye. Nevertheless, optical techniques such as Digital Image Correlation (DIC) are able to provide quantitative information of the motion with higher sensitivity than naked eye. For vibration analysis, mode shapes characterisation is one of the most interesting DIC performances. Full-field measurements provide higher spatial density than classical instrumentations or Scanning Laser Doppler Vibrometry. However, the accurateness of DIC is reduced at high frequencies asa consequence of the low displacements and hence it is habitually employed in low frequency spectra. In the current work, the combination of DIC and motion magnification is explored in order to provide numerical information in magnified videos and perform DIC mode shapes characterisation at unprecedented high frequencies through increasing the amplitude of displacements.
•We considered not only real data: population, geographic, and use.•We have used five different metaheuristic algorithms: GA, ILS, PSO, SA, and VNS.•We have configured all these algorithms ...automatically using irace.•We analyze the algorithm performances and the best model approach.•We can improve the current system of Malaga by adding more stations.
In this work, we solve the problem of finding the best locations to place stations for depositing/collecting shared bicycles. To do this, we model the problem as the p-median problem, that is a major existing localization problem in optimization. The p-median problem seeks to place a set of facilities (bicycle stations) in a way that minimizes the distance between a set of clients (citizens) and their closest facility (bike station).
We have used a genetic algorithm, iterated local search, particle swarm optimization, simulated annealing, and variable neighbourhood search, to find the best locations for the bicycle stations and study their comparative advantages. We use irace to parameterize each algorithm automatically, to contribute with a methodology to fine-tune algorithms automatically. We have also studied different real data (distance and weights) from diverse open data sources from a real city, Malaga (Spain), hopefully leading to a final smart city application. We have compared our results with the implemented solution in Malaga. Finally, we have analyzed how we can use our proposal to improve the existing system in the city by adding more stations.
In this Letter, we provide a general methodology to directly measure topological order in cold atom systems. As an application, we propose the realization of a characteristic topological model, ...introduced by Haldane, using optical lattices loaded with fermionic atoms in two internal states. We demonstrate that time-of-flight measurements directly reveal the topological order of the system in the form of momentum-space Skyrmions.
Glycerol is a non-toxic, non-hazardous, non-volatile, biodegradable, and recyclable liquid that is generated as a byproduct in the manufacture of biodiesel fuel from vegetable oils. Due to its easy ...availability, along with its unique combination of physical and chemical properties, glycerol has recently emerged as an economically appealing and safe solvent for organic synthesis. Recent works have also demonstrated that glycerol can be used as a hydrogen source in metal-catalyzed transfer hydrogenation of organic compounds, such as aldehydes, ketones, olefins and nitroarenes. Herein, the advances reached in this emerging field are reviewed. The utility of glycerol as solvent and reducing agent for the generation of metal nanoparticles is also briefly discussed.
•Motion magnification was applied for first time to perform 3D DIC.•Mode shapes of simple and complex shape elements were determined.•FEM models validates the employment of motion magnification in ...stereoscopic systems.•No aberration or incompatibility between sets of magnified images were observed.•Magnification solves the measurement of small periodic displacements with 3D-DIC.
Phase-based motion magnification has been proposed as an effective methodology to visualise Operational Deflection Shapes (ODSs) using a single camera. In recent work, magnification allowed the observation of these ODSs by naked eye or more advanced measurements on magnified images by using 2D Digital Image Correlation (DIC). The combination of a full-field optical technique and motion magnification shows a high potential improving DIC measurement and providing qualitative and quantitative information for the interpretation of ODSs. However, both motion magnification and the combination with 2D-DIC is limited to a few cases where plane elements experiences in-plane motion, mainly beam-like structures. In order to provide a more general application, in this study measurements on couples of magnified images using stereoscopic 3D-DIC were performed. A cantilever beam was employed for validation purposes, comparing the results with numerical models. Afterwards, a measurement application on a large curved panel was carried out to show full capabilities of the proposed methodology for 3D characterisation. Visualisation in slow-motion video format enables an intuitive understanding of the deformation. The adopted methodology demonstrates to be highly useful in low amplitude tests, involving the use of little exciters or high frequency applications.
Abstract
A theoretical analysis of binary collisions of quantum droplets under feasible experimental conditions is reported. Droplets formed from degenerate dilute Bose gases made up from binary ...mixtures of ultracold atoms are considered. Reliable expressions for the surface tension of the droplets are introduced based on a study of low energy excitations of their ground state within the random phase approximation. Their relevance is evaluated considering an estimation of the expected excitation energy having in mind the Thouless variational theorem. The surface tension expressions allow calculating the Weber number of the droplets involved in the collisions. Several regimes on the outcomes of the binary frontal collisions that range from the coalescence of the quantum droplets to their disintegration into smaller droplets are identified. Atoms losses of the droplets derived from self-evaporation and three-body scattering are quantified for both homo- and hetero-nuclear mixtures. Their control is mandatory for the observation of some interesting effects arising from droplets collisions.
Airway pathologies including cancer, trauma, and stenosis lack effective treatments, meanwhile airway transplantation and available tissue engineering approaches fail due to epithelial dysfunction. ...Autologous progenitors do not meet the clinical need for regeneration due to their insufficient expansion and differentiation, for which human induced pluripotent stem cells (hiPSCs) are promising alternatives. Airway epithelial patches are engineered by differentiating hiPSC‐derived airway progenitors into physiological proportions of ciliated (73.9 ± 5.5%) and goblet (2.1 ± 1.4%) cells on a silk fibroin–collagen vitrigel membrane (SF‐CVM) composite biomaterial for transplantation in porcine tracheal defects ex vivo and in vivo. Evaluation of ex vivo tracheal repair using hiPSC‐derived SF‐CVM patches demonstrate native‐like tracheal epithelial metabolism and maintenance of mucociliary epithelium to day 3. In vivo studies demonstrate SF‐CVM integration and maintenance of airway patency, showing 80.8 ± 3.6% graft coverage with an hiPSC‐derived pseudostratified epithelium and 70.7 ± 2.3% coverage with viable cells, 3 days postoperatively. The utility of bioengineered, hiPSC‐derived epithelial patches for airway repair is demonstrated in a short‐term preclinical survival model, providing a significant leap for airway reconstruction approaches.
Airway patches derived from human induced pluripotent stem cells (hiPSCs) and silk fibroin–collagen vitrigel membrane (SF‐CVM) composite biomaterials are engineered and their ability to repair airway defects is demonstrated in a short‐term porcine model. The patches successfully induce physiological proportions of mature epithelia. Importantly, hiPSC‐derived SF‐CVM patches integrate with surrounding tissue, preserve airway patency, and maintain a viable, pseudostratified epithelium.
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