Sulfonated Graphene-Based Materials as Heterogeneous Acid Catalysts for Solketal Synthesis by Acetalization of Glycerol

Acid catalysis plays a pivotal role in the industrial landscape due to its multifaceted contributions to various chemical processes in numerous sectors, including petrochemicals, polymers, food processing, and biodiesel production, among others. Sulfonated graphenes hold notable relevance as heterogeneous acid catalysts due to their unique combination of graphene’s structural properties and the introduction of sulfonic groups as catalytic acid sites. Herein, we report the preparation of three sulfonated graphene based materials – sulfonated reduced graphene oxide (rGO-SO3H), chlorosulfonated reduced graphene oxide (rGO-HSO3Cl) and sulfonated graphene oxide (GO-SO3H) – by different synthetic approaches. Physicochemical, textural, morphological, and acidic properties of all materials were characterized in detail by different instrumental techniques. Innovatively, these materials have been evaluated as heterogeneous acid catalysts in the solketal synthesis by acetalization of glycerol, which is considered an interesting building block to produce added-value products. The density of acidic active sites and hydrophobicity were found to be conditioning parameters of the resulting catalytic activity in terms of conversion and selectivity. The best catalytic performance was obtained by rGO-SO3H, reaching the maximum conversion towards solketal in 15 minutes under mild reaction conditions. The reusability and stability of all materials were also examined after three consecutive acetalization reactions with only a slight loss of catalytic activity

Visible-light-driven photocatalytic H2 production using composites of Co-Al layered double hydroxides and graphene derivatives

The direct conversion of solar energy into chemical energy represents an enormous challenge for current science. One of the commonly proposed photocatalytic systems is composed of a photosensitizer (PS) and a catalyst, together with a sacrificial electron donor (ED) when only the reduction of protons to H2 is addressed. Layered double hydroxides (LDH) have emerged as effective catalysts. Herein, two Co-Al LDH and their composites with graphene oxide (GO) or graphene quantum dots (GQD) have been prepared by co-precipitation and urea hydrolysis, which determined their structure and so their catalytic performance, giving H2 productions between 1409 and 8643 μmol g−1 using a ruthenium complex as PS and triethanolamine as ED at 450 nm. The influence of different factors, including the integration of both components, on their catalytic behavior, has been studied. The proper arrangement between the particles of both components seems to be the determining factor for achieving a synergistic interaction between LDH and GO or GQD. The novel Co-Al LDH composite with intercalated GQD achieved an outstanding catalytic efficiency (8643 μmol H2 g−1) and exhibited excellent reusability after 3 reaction cycles, thus representing an optimal integration between graphene materials and Co-Al LDH for visible light driven H2 photocatalytic production.

Visible-light-harvesting basolite-A520 metal organic framework for photocatalytic hydrogen evolution

A heterogeneous photosensitizer Ru@dpdhpzBASF-A520 has been successfully synthesized following an unprecedented strategy based on the incorporation of surface dipyridyl-dihydropyridazine adducts by Diels–Alder reaction on the aluminum fumarate units of the highly porous metal-organic framework (MOF) BASF-A520 and their further coordination to ruthenium metal centers. The characterization of the resulting metal-organic framework, including the ruthenium bipyridine-like photosensitizer moieties attached to its linkers, has been carried out by a wide variety of techniques, such as X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption-desorption isotherms, solid-state cross-polarization magic angle spinning carbon-13 nuclear magnetic resonance (13C CP/MAS NMR), X-ray photoelectron spectroscopy (XPS) and ultraviolet–visible (UV–vis) spectroscopy. The light absorption in the visible region shown by the resulting material, Ru@dpdhpzBASF-A520, has allowed its application as a single-site solid photosensitizer for photochemical reactions of hydrogen evolution in conjunction with Pt nanoparticles as catalyst, EDTA as sacrificial electron donor and MV as electron carrier. A remarkable photocatalytic activity after 72 h was achieved, with a TON of 1157 based on the heterogeneous ruthenium photosensitizer, in aqueous solution at pH 5.0, which confirmed the effective stabilization of the ruthenium dipyridyl -dihydropyridazine adducts on the MOF surface and the efficient electron injection from the photoexcited Ru@dpdhpzBASF-A520 to Pt nanoparticles mediated by MV electron carrier for hydrogen generation from water

Integral field spectroscopy of nitrogen overabundant blue compact dwarf galaxies

We study the spatial distribution of the physical properties and of oxygen and nitrogen abundances in three Blue Compact Dwarf Galaxiess (HS 0128+2832, HS 0837+4717 and Mrk 930) with a reported excess of N/O in order to investigate the nature of this excess and, particularly, if it is associated with Wolf-Rayet (WR) stars We have observed these BCDs by using PMAS integral field spectroscopy in the optical spectral range (3700 - 6900 {\AA}), mapping their physical-chemical properties, using both the direct method and appropriate strong-line methods. We make a statistical analysis of the resulting distributions and we compare them with the integrated properties of the galaxies. Our results indicate that outer parts of the three galaxies are placed on the "AGN-zone" of the [NII]/H{\alpha} vs. [OIII]/H{\beta} diagnostic diagram most likely due to a high N/O combined with the excitation structure in these regions. From the statistical analysis, it is assumed that a certain property can be considered as spatially homogeneous (or uniform) if a normal gaussian function fits its distribution in several regions of the galaxy. Moreover, a disagreement between the integrated properties and the mean values of the distribution usually appears when a gaussian does not fit the corresponding distribution. We find that for Mrk 930, the uniformity is found for all parameters, except for electron density and reddening. The rotation curve together with the H{\alpha} map and UV images, reveal a perturbed morphology and possible interacting processes. The N/O is found to be constant in the three studied objects at spatial scales of the order of several kpc so we conclude that the number of WR stars estimated from spectroscopy is not sufficient to pollute the ISM and to produce the observed N/O excess in these objectsComment: 17 pages, 14 figures, accepted for publication in Astronomy & Astrophysic

Physical and psychological paths toward less severe fibromyalgia: A structural equation model

The authors gratefully acknowledge all the participants for their collaboration and enthusiasm. We thank the assistant researchers involved in this study and all the members of the Physical Activity for HEaLth Promotion (PA-HELP; CTS-1018) research group.Supplementary data associated with this article can be found, in the online version, at https://doi.org/10.1016/j.rehab.2019.06.017.Objectives: Previous research suggested isolated associations of physical and psychological factors with fibromyalgia severity. Integration of physical and psychological, experienced and observed, modifiable factors associated with fibromyalgia severity in a single model will reveal therapeutic paths toward less severity of disease. We aimed to examine an encompassing model of determinants of fibromyalgia severity. Methods: This observational, population-based cross-sectional study included 569 people with fibromyalgia. An integrative model of fibromyalgia severity was tested by using structural equation modelling. This model included 8 factors: resilience, catastrophizing, active lifestyle, declarative memory, subjective fitness, objective fitness, psychological distress, and physical fatigue. Results: Two core paths were associated with reduced fibromyalgia severity: 1) a psychological path connecting high resilience and low catastrophizing with low distress and 2) a physical path, connecting a more active lifestyle (directly and via high objective and subjective physical fitness) with low fatigue. Additional interconnecting paths especially suggested a connection from the psychological to physical path. Our model explained 83% of the fibromyalgia severity. Conclusions: The present model integrated the complexity of mutually influencing factors of fibromyalgia severity, which may help to better understand the disease. It emphasised the importance of: 1) physical factors and psychological factors and their interconnections, 2) patients’ experiences and clinical measurements, and 3) positive and negative signs such as physical fitness and distress. Future longitudinal and experimental research should aim at testing the causal direction of the associations in the model as well as the clinical implications suggested by the model. For instance, to reduce fatigue, exercise should enhance not only objective fitness but also fitness-related perceptions. Reducing distress and fatigue seems crucial for lowering fibromyalgia severity.This work was supported by the Spanish Ministry of Economy and Competitiveness [I+D+i DEP2010-15639, I+D+I DEP2013-40908, I+D+I PSI2015-65241-R, and BES-2014-067612] and the Spanish Ministry of Education [FPU15/00002]. This study was funded in part by the University of Granada, Plan Propio de Investigación 2016, Excellence actions: Units of Excellence; Unit of Excellence on Exercise and Health (UCEES), and the Junta de Andalucía, Consejería de Conocimiento, Investigación y Universidades and European Regional Development Fund (ref. SOMM17/6107/UGR) and University of Jaén, Plan de Apoyo a la Investigación 2017-2019 [EI_SEJ07_2017]. The funders did not have any role in the study design, data collection and analyses, decision to publish, or preparation of the manuscript

Composites of Co-Al hydrotalcites and carbon nanomaterials for photocatalytic H2 production

Hydrogen is considered one of the main energy sources for the near future. Numerous efforts are currently underway for the direct transformation of solar energy into H2. Hydrotalcites are two-dimensional materials whose composition can be tuned relatively easily and, by themselves or in combination with other materials, are proving to be useful for the H2 evolution reaction. In this work, composites of a Co-Al hydrotalcite with carbon microspheres or nanotubes have been prepared. It has been shown that, in general, such composites improve H2 production. The influence of the nature, structure, and characteristics of the different materials on the reaction has been studied, as well as the role of each component and its mechanism. In particular, proper integration of both components and improved textural properties, as is the case of the composite with carbon microspheres, leads to a yield of 3820 µmol H2 g-1 at 5 h, more than twice that obtained with hydrotalcite alone, in the presence of Ru(bpy)3Cl2 as a photosensitizer and triethanolamine as an electron donor at 450 nm. The present methodology opens the door to the preparation of other composites for the improvement of the performance of photocatalytic systems for H2 production

Sociodemographic Factors Associated with the Satisfaction Level of Peruvian Dental Students with Virtual Classes During the Covid-19 Pandemic: A Prospective Bicentric Study

Ericka Albornoz-Palacios,1 Marysela Ladera-Castañeda,2 Gissela Briceño-Vergel,1 Nancy Córdova-Limaylla,1 Rosa Aroste-Andía,3 Emily Hernández-Huamaní,3 Percy Gavilán-Chávez,3 Miriam Castro-Rojas,2 Luis Cervantes-Ganoza,4 César Cayo-Rojas1 1School of Stomatology, Universidad Privada San Juan Bautista, Lima, Peru; 2Faculty of Dentistry and Postgraduate School, Universidad Nacional Federico Villarreal, Lima, Peru; 3School of Stomatology, Universidad Privada San Juan Bautista, Ica, Peru; 4Faculty of Stomatology, Universidad Inca Garcilaso de la Vega, Lima, PeruCorrespondence: César Cayo-Rojas, Av. Jose Antonio Lavalle Avenue 302-304, (Ex Hacienda Villa), Chorrillos, Lima, Peru, Email [email protected]: The pandemic caused by Covid-19 impacted all areas of social, economic and educational activity. When there is a high risk of spreading highly infectious diseases, education is usually the first service to be suspended. The objective was to evaluate the sociodemographic factors associated with the satisfaction level of Peruvian dental students with virtual classes during the Covid-19 pandemic.Methods: This observational, cross-sectional, analytical study evaluated 237 dental students from the capital city and one Peruvian province using a validated 13-item questionnaire to measure the level of satisfaction with virtual classes. Pearson’s chi-square test and a logit model were used to evaluate the associated factors such as age group, sex, marital status, monthly family income, area of residence, place of origin, occupation and computer use, considering a significance level of p< 0.05.Results: Of all students, 50.6%, 40.1% and 9.3% presented a good, average and poor level of satisfaction, respectively, with the virtual classes received. In addition, those with a monthly family income of less than 500 US dollars were 3.15 times more likely to have poor satisfaction compared to those with a monthly family income of more than 1000 US dollars (AOR = 3.15; 95% CI: 1.23– 8.05). The rest of the variables evaluated were not considered influential factors in the levels of satisfaction with the virtual classes received.Conclusión: Of all students, 50.6% and 9.3% reported good and poor satisfaction with virtual classes during the COVID-19 pandemic, respectively. Monthly family income of less than 500 US dollars was an influential factor. In addition, the variables age group, sex, marital status, area of residence, place of origin, occupation and computer use were not found to be influential factors.Keywords: e-learning, online learning, sociodemographic factors, satisfaction level, virtual classrooms, dentistry, Covid − 1

Augmented Reality in a Hiking Tour of the Miocene Geoheritage of the Central Algarve Cliffs (Portugal)

Acceso electrónico sólo desde el IGMEEight sites with geological (including palaeontological and geomorphological) interest (geosites) representative of the Lower and Middle Miocene carbonate deposits near Albufeira in central Algarve (southern Portugal) have been selected based on our extended working experience. The sites can be visited by hiking in a 1-day field trip. A virtual 3D tour of the georeferenced sites was produced using augmented reality technique and geoinformatic tools which integrate thematic digital layers such as geological maps and orthophotos. Every stop in the tour includes descriptive and graphic elements that can be viewed in free virtual globes (e.g. Google Earth) combined with diagrams, photographs and information sheets that quantitatively assess the cultural-touristic, educational and scientific value of the geosites. A virtual flight itinerary compatible with video formats in the new free technologies (smartphones, tablets and iPads) is also presented.Departamento de Geología, Universidad de Salamanca, EspañaGeoBioTec, Departamento de Ciências da Terra, Universidade Nova de Lisboa, PortugalDepartamento de Estratigrafía, Universidad Complutense de Madrid, EspañaMuseo Nacional de Ciencias Naturales, Consejo Superior de Investigaciones Científicas, EspañaLaboratório Nacional de Geologia e Energia, Portuga

Resistant starch can improve insulin sensitivity independently of the gut microbiota

Background: Obesity-related diseases, including type 2 diabetes and cardiovascular disease, have reached epidemic proportions in industrialized nations, and dietary interventions for their prevention are therefore important. Resistant starches (RS) improve insulin sensitivity in clinical trials, but the mechanisms underlying this health benefit remain poorly understood. Because RS fermentation by the gut microbiota results in the formation of physiologically active metabolites, we chose to specifically determine the role of the gut microbiota in mediating the metabolic benefits of RS. To achieve this goal, we determined the effects of RS when added to a Western diet on host metabolism in mice with and without a microbiota. Results: RS feeding of conventionalized mice improved insulin sensitivity and redressed some of the Western diet-induced changes in microbiome composition. However, parallel experiments in germ-free littermates revealed that RS-mediated improvements in insulin levels also occurred in the absence of a microbiota. RS reduced gene expression of adipose tissue macrophage markers and altered cecal concentrations of several bile acids in both germ-free and conventionalized mice; these effects were strongly correlated with the metabolic benefits, providing a potential microbiota-independent mechanism to explain the physiological effects of RS. Conclusions: This study demonstrated that some metabolic benefits exerted by dietary RS, especially improvements in insulin levels, occur independently of the microbiota and could involve alterations in the bile acid cycle and adipose tissue immune modulation. This work also sets a precedent for future mechanistic studies aimed at establishing the causative role of the gut microbiota in mediating the benefits of bioactive compounds and functional foods