Role of proteoglycans on skin ageing: a review

This work analyses the role of proteoglycans on skin ageing, influenced by the presence of glycosylated proteins, which exercise diverse functions on the skin. They are essential components that restore the cells, providing hydration, maintaining hydration of the extracellular matrix, preventing the formation of wrinkles thanks to their ability to combine to other molecules such as collagen or hyaluronic acid and favouring the smoothness of the skin texture. The use of these proteins is a very recent and promising topic, since their application may revolutionize skin ageing therapies. Of the existing proteoglycans, decorin, versican and perlecan are of special note, playing a fundamental role on skin.     

Nonwoven Ni–NiO/carbon fibers for electrochemical water oxidation

The development of technologically efficient anodes for water oxidation is crucial to improve hydrogen production via water splitting. Electrodes based on metallic active sites dispersed in carbon matrices have been shown to be an attractive way to attain this goal. However, challenges remain to prevent catalyst agglomeration that otherwise can result in a decrease of performance over time.In this work, we report an alternative and efficient method to produce nickel-nickel oxide nanoparticles-embedded in carbon nanofibers (Ni–NiO/C), by the solution blow spinning (SBS) process. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses show the carbon nanofibrillar matrix as a robust support, with well-dispersed nickel nanoparticles on the surface. The responses of the linear scanning voltammetry, cyclic voltammetry and electrochemical impedance spectroscopy demonstrate how a small fraction of nickel on the fiber surface (≈1.2–5.3%) is enough to promote substantial improvement in performance (η = 278 and 309 mV vs RHE for 10 mA cm^?2) and a significant turnover frequency (TOF) values of 1.38 (η = 278) and 1.30 s^?1 (η = 309). These promising results are correlated with a large amount of Ni³⁺ present on the fiber surfaces, as identified by X-ray Photoelectron Spectroscopy (XPS). This work provides a low-cost and rapid preparation technique that can be extended for the manufacture of a wide variety of electrodes based on metals supported on carbon nanofibers.     

Identification of a new oxidation/ dissolution mechanism for boria-accelerated SiC oxidation

Boria effects on accelerated SiC oxidation kinetics were investigated by conducting thermogravimetric analysis on SiC substrates coated with sol-gel derived borosilicate glass isothermally exposed to dry O₂ and argon at 800°C and 1200°C for 100 hours. Boria concentrations in the glass coatings were 0, 14-38, and 92-94 mol%, balance silica. Accelerated weight gain was observed for SiC exposures in dry O₂ at 800°C when boria concentrations were ≥ 92 mol%, corroborated by oxide thickness ranging from 3.5 to 10 µm. The oxide thickness predicted for pure SiC exposed to these conditions in the absence of boria is 0.15 µm. Microstructural analysis of SiC surfaces after oxide removal revealed that boria etched the underlying SiC substrate. Oxidation exposures at 1200°C in dry O₂ suppressed boria effects on accelerating SiC oxidation kinetics due to rapid boria volatilization coupled with the formation of a protective thermally grown silica scale. Accelerated weight gain or oxide growth did not occur with argon exposures at either temperature. A new mechanism for boria-accelerated SiC surface-reaction kinetics is presented based on evidence for boria etching of SiC.     

Progress in the design of zeolite catalysts for biomass conversion into biofuels and bio-based chemicals

This article reviews the recent advances in the development of zeolite catalysts for biomass valorization processes to produce both biofuels and/or bio-based chemicals, which is an emerging and fast expanding field. The work deals with different types of feedstocks, including vegetable oils, lignocellulose and sugars, as well as with a number of relevant intermediates and platform molecules. Transformation of biomass into valuable products is hindered by a number of factors, mainly related to its complex composition, as biomass typically consists of bulky molecules with high oxygen content. Accordingly, biomass processing usually requires the combination of multiple steps and severe conditions, hence concepts like atom efficiency, product selectivity, and catalyst deactivation become of special relevance. A great progress has been achieved in the past years engineering the properties of zeolites for being adapted to the challenges associated to biomass valorization. The possibility of tailoring the main physicochemical properties of zeolites has become now a reality, being the major reason that explains the success achieved by this class of materials in a growing variety of biomass conversion pathways, as those described in this work: catalytic cracking and pyrolysis, hydrotreatments, with special relevance for hydrodeoxygenation processes, as well as in a high number of condensation, isomerization, and dehydration reactions. Thus, the development of hierarchical zeolites, exhibiting enhanced accessibility, and the possibility of introducing and combining in a controlled way different types of active sites (Brønsted and Lewis acid centers, basic sites, and metal phases) are the main basis of the excellent performance of zeolites in numerous biomass conversion routes.     

Characterization of precipitates formed in X7R 0603 BME-MLCC during sintering

In the current study two different batches of X7R-0603 BME-MLCCs displayed dissimilar electrical performance, despite having the same chemical composition, tape casting, and sintering conditions; with the only difference between them being the ore deposits where the raw materials were extracted from to synthesize the BaTiO₃. Specifically, they presented different electrical response to highly accelerated life tests (HALT). Although the chemical analysis of each slip showed the same composition, the trace elements of the BaTiO₃ sources could have acted as dopants or produced different secondary phases. A search for precipitates in the two samples was conducted by means of Scanning (SEM) and Transmission Electron Microscopy (TEM) techniques. SEM observations confirmed the presence of precipitates formed within the structure of the MLCCs exhibiting the greatest decrement in their electrical resistance results during the HALT. In order to further characterize the observed precipitates, samples were prepared by Focused Ion Beam (FIB) lift-out method, to make TEM characterization of specific precipitates feasible. TEM studies were performed on the precipitates to obtain electron diffraction patterns and complementary Energy Dispersive X-Ray Spectroscopy (EDXS) chemical analysis. Based on the crystal and chemical data obtained, it can be concluded that the precipitates are a hexagonal anhydrous silicate oxyapatite phase with a stoichiometry of Ca₃Y₁₆Si₁₀O₁₃, and lattice parameters of a = 0.9353 nm and c = 0.6970 nm; this phase was not found in the JCPDS data base. Differences in raw materials coming from different ore deposits can produce undesired precipitates that affect the electrical performance of MLCCs.     

Spatial distribution and temporal variation of metals in the vicinity of a municipal solid waste incinerator after a modernization of the flue gas cleaning systems of the facility

In June 1994 and 1997, the concentrations of a number of elements were determined in soil and herbage samples collected in the vicinity of a municipal solid waste incinerator (MSWI) (Tarragona, Catalonia, Spain). In August 1997, an adaptation to the EU legislation on pollutant emissions from the stack was carried out to the incinerator. In June 1999, soil and herbage samples were collected again at the same sampling points and the levels of arsenic (As), cadmium (Cd), chromium (Cr), lead (Pb), manganese (Mn), mercury (Hg), nickel (Ni) and vanadium (V) were measured by ICP-MS or AAS with graphite furnace. The results are compared with those obtained in the 1994 and 1997 surveys. In the period 1997-1999, the only significant changes in soil levels corresponded to Cd and Pb, with decreases of 21.0% and 53.5%, respectively. In vegetation, only Mn levels showed a significant reduction, which contrasts with the notable increases found in the concentrations of As, Hg and Ni. According to the results of this survey, it seems evident that other metal emission sources in the same area of study are masking the environmental improvements carried out in the MSWI.