Activation of polymer blend carbon nanofibres by alkaline hydroxides and their hydrogen storage performances

In the present work we study the hydroxide activation (NaOH and KOH) of phenol-formaldehyde resin derived CNFs prepared by a polymer blend technique to prepare highly porous activated carbon nanofibres (ACNFs). Morphology and textural characteristics of these ACNFs were studied and their hydrogen storage capacities at 77 K (at 0.1 MPa and at high pressures up to 4 MPa) were assessed, and compared, with reported capacities of other porous carbon materials. Phenol-formaldehyde resin derived carbon fibres were successfully activated with these two alkaline hydroxides rendering highly microporous ACNFs with reasonable good activation process yields up to 47 wt.% compared to 7 wt.% yields from steam activation for similar surface areas of 1500 m2/g or higher. These nano-sized activated carbons present interesting H2 storage capacities at 77 K which are comparable, or even higher, to other high quality microporous carbon materials. This observation is due, in part, to their nano-sized diameters allowing to enhance their packing densities to 0.71 g/cm3 and hence their resulting hydrogen storage capacities.

Environmental and Occupational Optometry. Lesson 6 (Course 2013-2014)

Tema 6: Diseño del entorno visual. Actividad propuesta no. 3.

Study of dopamine reactivity on platinum single crystal electrode surfaces

Dopamine is the biological molecule responsible, among other functions, of the heart beat and blood pressure regulation. Its loss, in the human body, can result in serious diseases such as Parkinson's, schizophrenia or depression. Structurally, this molecule belongs to the group of catecholamines, together with epinephrine (adrenaline) and norepinephrine (noradrenaline). The hydroquinone moiety of the molecule can be easily oxidized to quinone, rendering the electrochemical methods a convenient approach for the development of dopamine biosensors. The reactivity of similar aromatic molecules, such as catechol and hydroquinone, at well-ordered platinum surfaces, has recently been investigated in our group. In this paper, we extend these studies to the structurally related molecule dopamine. The study has been performed in neutral pH, since this is closer to the natural conditions for these molecules in biological media. Cyclic voltammetry and in situ infra-red spectroscopy have been combined to extract information about the behavior of this molecule on well-defined platinum surfaces. Dopamine appears to be electrochemically active and reveals interesting adsorption phenomena at low potentials (0.15–0.25 V vs RHE), sensitive to the single crystal orientation. The adsorption of dopamine on these surfaces is very strong, taking place at much lower potentials than the electron transfer from solution species. Specifically, the voltammetry of Pt(1 1 1) and Pt(1 0 0) in dopamine solutions shows an oxidation peak at potentials close to the onset of hydrogen evolution, which is related to the desorption of hydrogen and the adsorption of dopamine. On the other hand, adsorption on Pt(1 1 0) is irreversible and the surface appears totally blocked. Spectroscopic results indicate that dopamine is adsorbed flat on the surface. At potentials higher than 0.6 V vs RHE the three basal planes show a common redox process. The initial formation of the quinone moiety is followed by a chemical step resulting in the formation of 5,6-dihydroxyindoline quinone as final product. This oxidation process has also been investigated by vibrational spectroscopy.

Global color estimation of special-effect coatings from measurements by commercially available portable multiangle spectrophotometers

Colors of special-effect coatings have strong dependence on illumination/viewing geometry and an appealing appearance. An open question is to ask about the minimum number of measurement geometries required to completely characterize their observed color shift. A recently published principal components analysis (PCA)-based procedure to estimate the color of special-effect coatings at any geometry from measurements at a reduced set of geometries was tested in this work by using the measurement geometries of commercial portable multiangle spectrophotometers X-Rite MA98, Datacolor FX10, and BYK-mac as reduced sets. The performance of the proposed PCA procedure for the color-shift estimation for these commercial geometries has been examined for 15 special-effect coatings. Our results suggest that for rendering the color appearance of 3D objects covered with special-effect coatings, the color accuracy obtained with this procedure may be sufficient. This is the case especially if geometries of X-Rite MA98 or Datacolor FX10 are used.

3D teaching: the ideal complement for professionals in design and construction

Today, the requirement of professional skills to university students is constantly increasing in our society. In our opinion, the content offered in official degrees need to be nourished with different variables, enriching their global professional knowledge in a parallel way; that is why, in recent years, there is a great multiplicity of complementary courses at university. One of the most socially demanded technical requirements within the architectural, design or engineering field is the management of 3D drawing software, becoming an indispensable reality in these sectors. Thus, this specific training becomes essential over two-dimension traditional design, because the inclusion of great possibilities of spatial development that go beyond conventional orthographic projections (plans, sections or elevations), allowing modelling and rotation of the selected items from multiple angles and perspectives. Therefore, this paper analyzes the teaching methodology of a complementary course for those technicians in the construction industry interested in computer-aided design, using modelling (SketchupMake) and rendering programs (Kerkythea). The course is developed from the technician point of view, by learning computer management and its application to professional development from a more general to a more specific view through practical examples. The proposed methodology is based on the development of real examples in different professional environments such as rehabilitation, new constructions, opening projects or architectural design. This multidisciplinary contribution improves criticism of students in different areas, encouraging new learning strategies and the independent development of three-dimensional solutions. Thus, the practical implementation of new situations, even suggested by the students themselves, ensures active participation, saving time during the design process and the increase of effectiveness when generating elements which may be represented, moved or virtually tested. In conclusion, this teaching-learning methodology improves the skills and competencies of students to face the growing professional demands of society. After finishing the course, technicians not only improved their expertise in the field of drawing but they also enhanced their capacity for spatial vision; both essential qualities in these sectors that can be applied to their professional development with great success.

Design of Activated Carbon/Activated Carbon Asymmetric Capacitors

Supercapacitors are energy storage devices that offer a high power density and a low energy density in comparison with batteries. Their limited energy density can be overcome by using asymmetric configuration in mass electrodes, where each electrode works within their maximum available potential window, rendering the maximum voltage output of the system. Such asymmetric capacitors are optimized using the capacitance and the potential stability limits of the electrodes, with the reliability of the design largely depending on the accuracy and the approach taken for the electrochemical characterization. Therefore, the performance could be lower than expected and even the system could break down, if a well thought out procedure is not followed. In this work, a procedure for the development of asymmetric supercapacitors based on activated carbons is detailed. Three activated carbon materials with different textural properties and surface chemistry have been systematically characterized in neutral aqueous electrolyte. The asymmetric configuration of the masses of both electrodes in the supercapacitor has allowed to cover a higher potential window, resulting in an increase of the energy density of the three devices studied when compared with the symmetric systems, and an improved cycle life.

Synthesis of Ordered Mesoporous Carbon Materials by Dry Etching

A novel synthesis method for ordered mesoporous carbons is presented. The inverse replication of a silica template was achieved using the carbonization of sucrose within mesoporous KIT-6. Instead of liquid acid etching, as in classical nanocasting, a novel dry chlorine etching procedure for template removal is presented for the first time. The resultant ordered mesostructured carbon material outperforms carbons obtained by conventional hard templating with respect to high specific micro- and mesopore volumes (0.6 and 1.6 cm3 g−1, respectively), due to the presence of a hierarchical pore system. A high specific surface area of 1671 m2 g−1 was achieved, rendering this synthesis route a highly convenient method to produce ordered mesoporous carbons.