Intersection of Data Science and Smart Destinations: A Systematic Review.

This systematic review adopts a formal and structured approach to review the intersection of data science and smart tourism destinations in terms of components found in previous research. The study period corresponds to 1995-2021 focusing the analysis mainly on the last years (2015-2021), identifying and characterizing the current trends on this research topic. The review comprises documentary research based on bibliometric and conceptual analysis, using the VOSviewer and SciMAT software to analyze articles from the Web of Science database. There is growing interest in this research topic, with more than 300 articles published annually. Data science technologies on which current smart destinations research is based include big data, smart data, data analytics, social media, cloud computing, the internet of things (IoT), smart card data, geographic information system (GIS) technologies, open data, artificial intelligence, and machine learning. Critical research areas for data science techniques and technologies in smart destinations are public tourism marketing, mobility-accessibility, and sustainability. Data analysis techniques and technologies face unprecedented challenges and opportunities post-coronavirus disease-2019 (COVID-19) to build on the huge amount of data and a new tourism model that is more sustainable, smarter, and safer than those previously implemented.

Confinement Situation of the Spanish Population during the Health Crisis of COVID-19: Resilience Mediation Process in the Relationship of Dispositional Optimism and Psychological Well-Being.

The pandemic generated by COVID-19 is one of the most complex challenges humanity has faced in recent years. This study aims to explore the levels of dispositional optimism, resilience and psychological well-being in the sociodemographic and economic situation produced during the state of alarm and to investigate the resilience mediation between optimism and psychological well-being. The sample included 566 volunteers from Spain (73.5% women; M = 40.2 years, SD = 12.8). An ad hoc questionnaire was applied to request socioeconomic data and dispositional optimism (LOT-R). Resilience and psychological well-being were, respectively, evaluated by the Ryff scale and the Wagnild and Young scale. The results show that older and people with higher educational levels are more optimistic and have better psychological well-being. Well-being is also greater in married, divorced and widowed people and in those who have lived in outdoor spaces. However, those with spaced housing were more optimistic. Finally, it was found that the most optimistic people have better psychological well-being and that this is increased by the mediation process exercised by the ability to overcome adversity, provided age and educational level are controlled. It can be concluded that the design of preventive programs focused on improving strengths, positive emotions and skills in the population would be convenient to protect mental health.

Synthesis and Characterization of Renewable Polyester Coil Coatings from Biomass-Derived Isosorbide, FDCA, 1,5-Pentanediol, Succinic Acid, and 1,3-Propanediol.

Biomass-derived polyester coatings for coil applications have been successfully developed and characterized. The coatings were constituted by carbohydrate-derived monomers, namely 2,5-furan dicarboxylic acid, isosorbide, succinic acid, 1,3-propanediol, and 1,5-pentanediol, the latter having previously been used as a plasticizer rather than a structural building unit. The effect of isosorbide on the coatings is widely studied. The inclusion of these monomers diversified the mechanical properties of the coatings, and showed an improved performance against common petrochemical derived coatings. This research study provides a range of fully bio-derived polyester coil coatings with tunable properties of industrial interest, highlighting the importance of renewable polymers towards a successful bioeconomy.

A versatile sonication-assisted deposition-reduction method for preparing supported metal catalysts for catalytic applications.

This work aims to develop a rapid and efficient strategy for preparing supported metal catalysts for catalytic applications. The sonication-assisted reduction-precipitation method was employed to prepare the heterogeneous mono- and bi-metallic catalysts for photocatalytic degradation of methyl orange (MO) and preferential oxidation (PROX) of CO in H2-rich gas. In general, there are three advantages for the sonication-assisted method as compared with the conventional methods, including high dispersion of metal nanoparticles on the catalyst support, the much higher deposition efficiency (DE) than those of the deposition-precipitation (DP) and co-precipitation (CP) methods, and the very fast preparation, which only lasts 10-20s for the deposition. In the AuPd/TiO2 catalysts series, the AuPd(3:1)/TiO2 catalyst is the most active for MO photocatalytic degradation; while for PROX reaction, Ru/TiO2, Au-Cu/SBA-15 and Pt/γ-Al2O3 catalysts are very active, and the last one showed high stability in the lifetime test. The structural characterization revealed that in the AuPd(3:1)/TiO2 catalyst, Au-Pd alloy particles were formed and a high percentage of Au atoms was located at the surface. Therefore, this sonication-assisted method is efficient and rapid in the preparation of supported metal catalysts with obvious structural characteristics for various catalytic applications.

High activity redox catalysts synthesized by chemical vapor impregnation.

The use of precious metals in heterogeneous catalysis relies on the preparation of small nanoparticles that are stable under reaction conditions. To date, most conventional routes used to prepare noble metal nanoparticles have drawbacks related to surface contamination, particle agglomeration, and reproducibility restraints. We have prepared titania-supported palladium (Pd) and platinum (Pt) catalysts using a simplified vapor deposition technique termed chemical vapor impregnation (CVI) that can be performed in any standard chemical laboratory. These materials, composed of nanoparticles typically below 3 nm in size, show remarkable activity under mild conditions for oxidation and hydrogenation reactions of industrial importance. We demonstrate the preparation of bimetallic Pd-Pt homogeneous alloy nanoparticles by this new CVI method, which show synergistic effects in toluene oxidation. The versatility of our CVI methodology to be able to tailor the composition and morphology of supported nanoparticles in an easily accessible and scalable manner is further demonstrated by the synthesis of Pdshell-Aucore nanoparticles using CVI deposition of Pd onto preformed Au nanoparticles supported on titania (prepared by sol immobilization) in addition to the presence of monometallic Au and Pd nanoparticles.

Switching-off toluene formation in the solvent-free oxidation of benzyl alcohol using supported trimetallic Au-Pd-Pt nanoparticles.

Trimetallic Au-Pd-Pt nanoparticles have been supported on activated carbon by the sol-immobilisation method. They are found to be highly active and selective catalysts for the solvent-free aerobic oxidation of benzyl alcohol. The addition of Pt promotes the selectivity to the desired product benzaldehyde at the expense of toluene formation. Detailed aberration corrected STEM-XEDS analysis confirmed that the supported particles are indeed Au-Pd-Pt ternary alloys, but also identified composition fluctuations from particle-to-particle which vary systematically with nanoparticle size.

Partial oxidation of ethane to oxygenates using Fe- and Cu-containing ZSM-5.

Iron and copper containing ZSM-5 catalysts are effective for the partial oxidation of ethane with hydrogen peroxide giving combined oxygenate selectivities and productivities of up to 95.2% and 65 mol kgcat(-1) h(-1), respectively. High conversion of ethane (ca. 56%) to acetic acid (ca. 70% selectivity) can be observed. Detailed studies of this catalytic system reveal a complex reaction network in which the oxidation of ethane gives a range of C2 oxygenates, with sequential C-C bond cleavage generating C1 products. We demonstrate that ethene is also formed and can be subsequently oxidized. Ethanol can be directly produced from ethane, and does not originate from the decomposition of its corresponding alkylperoxy species, ethyl hydroperoxide. In contrast to our previously proposed mechanism for methane oxidation over similar zeolite catalysts, the mechanism of ethane oxidation involves carbon-based radicals, which lead to the high conversions we observe.

Catalytic and mechanistic insights of the low-temperature selective oxidation of methane over Cu-promoted Fe-ZSM-5.

The partial oxidation of methane to methanol presents one of the most challenging targets in catalysis. Although this is the focus of much research, until recently, approaches had proceeded at low catalytic rates (<10 h(-1)), not resulted in a closed catalytic cycle, or were unable to produce methanol with a reasonable selectivity. Recent research has demonstrated, however, that a system composed of an iron- and copper-containing zeolite is able to catalytically convert methane to methanol with turnover frequencies (TOFs) of over 14,000 h(-1) by using H(2)O(2) as terminal oxidant. However, the precise roles of the catalyst and the full mechanistic cycle remain unclear. We hereby report a systematic study of the kinetic parameters and mechanistic features of the process, and present a reaction network consisting of the activation of methane, the formation of an activated hydroperoxy species, and the by-production of hydroxyl radicals. The catalytic system in question results in a low-energy methane activation route, and allows selective C(1)-oxidation to proceed under intrinsically mild reaction conditions.

Promotion of phenol photodecomposition over TiO2 using Au, Pd, and Au-Pd nanoparticles.

Noble metal nanoparticles (Au, Pd, Au-Pd alloys) with a narrow size distribution supported on nanocrystalline TiO(2) (M/TiO(2)) have been synthesized via a sol-immobilization route. The effect of metal identity and size on the photocatalytic performance of M/TiO(2) has been systematically investigated using phenol as a probe molecule. A different phenol degradation pathway was observed when using M/TiO(2) catalysts as compared to pristine TiO(2). We propose a mechanism to illustrate how the noble metal nanoparticles enhance the efficiency of phenol decomposition based on photoreduction of p-benzoquinone under anaerobic conditions. Our results suggest that the metal nanoparticles not only play a role in capturing photogenerated electrons, but are strongly involved in the photocatalytic reaction mechanism. The analysis of the reaction intermediates allows us to conclude that on M/TiO(2) undesired redox reactions that consume photogenerated radicals are effectively suppressed. The analysis of the final products shows that the reusability performance of the catalyst is largely dependent on the pretreatment of the catalyst and the identity of the metal nanoparticle. Interestingly, the as-prepared Pd and Au-Pd decorated TiO(2) materials exhibit excellent long-term photoactivity, in which ~90% of the phenol can be fully decomposed to CO(2) in each cycle.

Oxidation of glycerol using gold-palladium alloy-supported nanocrystals.

The use of bio-renewable resources for the generation of materials and chemicals continues to attract significant research attention. Glycerol, a by-product from biodiesel manufacture, is a highly functionalised renewable raw material, and in this paper the oxidation of glycerol in the presence of base using supported gold, palladium and gold-palladium alloys is described and discussed. Two supports, TiO(2) and carbon, and two preparation methods, wet impregnation and sol-immobilisation, are compared and contrasted. For the monometallic catalysts prepared by impregnation similar activities are observed for Au and Pd, but the carbon-supported monometallic catalysts are more active than those on TiO(2). Glycerate is the major product and lesser amounts of tartronate, glycolate, oxalate and formate are observed, suggesting a sequential oxidation pathway. Combining the gold and palladium as supported alloy nanocrystals leads to a significant enhancement in catalyst activity and the TiO(2)-supported catalysts are significantly more active for the impregnated catalysts. The use of a sol-immobilisation preparation method as compared to impregnation leads to the highest activity alloy catalysts and the origins of these activity trends are discussed.

Solvent-free oxidation of benzyl alcohol using Au-Pd catalysts prepared by sol immobilisation.

We report the preparation of Au-Pd nanocrystalline catalysts supported on TiO(2) and carbon prepared via a sol-immobilisation technique using three different preparation strategies; namely, simultaneous formation of the sols for both metals or initial formation of a seed sol of one of the metals followed by a separate step in which a coating sol of the second metal is added. The catalysts have been structurally characterised using a combination of transmission electron microscopy and X-ray photoelectron spectroscopy. The catalysts have been evaluated for the oxidation of benzyl alcohol under solvent-free conditions. The catalysts prepared using the sol immobilisation technique show higher activity when compared with catalysts prepared by impregnation, particularly as lower metal concentrations can be used. The Au-Pd catalysts were all more active than the corresponding monometallic supported Au or Pd catalysts. For 1 wt% Au-Pd/TiO(2) the order of metal addition in the preparation was not observed to be significant with respect to selectivity or activity. However, the 1 wt% Au-Pd/carbon catalysts are more active but less selective to benzaldehyde than the TiO(2)-supported catalysts when compared at iso-conversion. Furthermore, for the carbon-supported catalyst the order of metal addition has a very marked affect on activity. The carbon-supported catalysts are also more significantly affected by heat treatment, e.g. calcination at 400 degrees C leads to the activity being decreased by an order of magnitude, whereas the TiO(2)-supported catalysts show a 50% decrease in activity. Toluene is observed as a by-product of the reaction and conditions have been identified that minimise its formation. It is proposed that toluene and benzaldehyde are formed by competing parallel reactions of the initial benzyl intermediate via an adsorbed benzylidene species that can either be hydrogenated or oxidised. Hence, conditions that maximise the availability of oxygen on the catalyst surface favour the synthesis of benzaldehyde.

Au-Pd supported nanocrystals prepared by a sol immobilisation technique as catalysts for selective chemical synthesis.

Catalysis by gold and gold-palladium nanoparticles has attracted significant research attention in recent years. These nanocrystalline materials have been found to be highly effective for selective and total oxidation, but in most cases the catalysts are prepared using precipitation or impregnation. We report the preparation of Au-Pd nanocrystalline catalysts supported on carbon prepared via a sol-immobilisation technique and these have been compared with Au-Pd catalysts prepared via impregnation. The catalysts have been evaluated for two selective chemical syntheses, namely, oxidation of benzyl alcohol and the direct synthesis of hydrogen peroxide. The catalysts have been structurally characterised using a combination of scanning transmission electron microscopy and X-ray photoelectron spectroscopy. The catalysts prepared using the sol immobilisation technique show higher activity when compared with catalysts prepared by impregnation as they are more active for both hydrogen peroxide synthesis and hydrogenation, and also for benzyl alcohol oxidation. The method facilitates the use of much lower metal concentrations which is a key feature in catalyst design, particularly for the synthesis of hydrogen peroxide.