Emissivity of spinel and titanate structures aiming at the development of industrial high-temperature ceramic coatings

High-emissivity coatings have been pointed out as a promising energy-saving solution for industrial furnaces since their development in the aerospace area. However, due to a lack of in-depth knowledge of radiation heat transfer and thermal-optical interactions, as well as the struggle to obtain proper emissivity values, commercial versions of such coatings have not yet been widely established. In this work, the evaluation of some fundamentals on thermal-optical properties, and their potential applications, led to the development of engineered structures of usual inexpensive oxides, such as the titanate and spinel ones, which presented improved emissivity values, even at high temperatures (1500 °C), when compared to commercial references. The findings of these compounds indicated a considerable cost-effective saving potential for large industrial furnaces.     

Sweet Potato Bioethanol Upgrade Using Organic and Inorganic Dehydrating Agents

Glycerol, ethylene glycol, and quicklime were used as alternative dehydrating agents to obtain anhydrous bioethanol from sweet potato. The assay conditions were standardized using high bioethanol grades. For organic reagents, three volumetric ratios were studied whereas for quicklime, five concentrations were evaluated. Quicklime led to the highest bioethanol purity of 99.4 °GL, followed by glycerol and ethylene glycol, reaching 96.9 and 96.6 °GL, respectively. Glycerol and ethylene glycol were reused for 4 cycles with negligible loss of efficiency; however, the yield decreased by up to 8 %.     

Topical emulsions containing ceramides: Effects on the skin barrier function and anti‐inflammatory properties

The barrier properties of the stratum corneum (SC) are largely dependent on the intactness of the lipid lamellae that surround the corneocytes. Ceramides, fatty acids, and cholesterol together with hydrocortisone (HC) have thus been proposed as protective or therapeutic agents against xerosis and atopic dermatitis (AD). However, topical delivery of these substances is still a challenge because of the excellent barrier function of the skin. The aim of the present study was to develop a formulation with combined anti‐inflammatory/barrier repair properties. In order to achieve this goal, a new non‐ionic O/W emulsion (CerEmulsion) containing skin barrier lipids and HC was prepared. Its physicochemical and microbiological stability and skin permeation performance were compared to a blank emulsion (NoCerEmulsion). Placebos described as PlaceboCerEmulsion and PlaceboNoCerEmulsion of CerEmulsion and NoCerEmulsion, respectively, were also prepared in order to study the transepidermal water loss (TEWL) profiles. The emulsions presented white glossy and pourable characteristics with an acidic pH. CerEmulsion showed smaller droplet sizes and higher viscosity values (5000 mPas) while NoCerEmulsion presented viscosity values of 2000 mPas. Crystalline structures were prominent in both emulsions. The microbiological analysis showed that the results were within the established specification limits. CerEmulsion and NoCerEmulsion have shown similar release profiles and CerEmulsion presented a similar anti‐inflammatory activity in vivo when compared with a commercially available 1% HC emulsion. Both emulsions were chemically, physically, and microbiologically stable. TEWL was significantly lower for the group treated with PlaceboCerEmulsion, suggesting that skin hydration was higher with this ceramide‐containing formulation. Practical applications: In this work, the authors develop and characterize a new non‐ionic HC/ceramide‐dominant O/W emulsion as a topical therapy for the improvement of skin barrier abnormalities in atopic dermatitis (AD). This unique formulation includes high concentrations of three lipids (ceramides, cholesterol, and free fatty acids) and paraffin. Its use is recommended for AD patients ≥6 months of age. It is also indicated for the management and relief of burning and itching associated with various dermatoses, including AD, irritant contact dermatitis, and radiation dermatitis.     

Optimized route for the production of zirconia structures with controlled surface porosity for biomedical applications

Zirconia structures with controlled surface porosity may be used in several biomedical and engineering applications. This work aimed at developing a processing route for the production of zirconia structures with porous surfaces, using the dip coating method and without pore forming additives. Zirconia powders (~ 40?µm diameter) were used in the dip coating suspensions in three different forms: agglomerates (as received), pre-sintered (1150?°C, 1?h) and sintered (1500?°C, 2?h). The addition of fine particles (< 10?µm diameter) to the suspensions, in different contents, were tested to act as binder for the larger particles. Zirconia disk-shape compacts were dipped in the different suspensions and sintered. Pre-sintered powders were found to be the most adequate for producing the porous surface. The optimized binder content was determined as a function of the porous layer strength. A feasible route could be successfully established for the production of zirconia structures with porous surface.     

Writing Centers and Students with Disabilities: The User-centered Approach,Participatory Design,and Empirical Research as Collaborative Methodologies

This article discusses issues of accessibility and how user-centered and participatory approaches can inform empirical research to guide the Universal Design of virtual spaces and influence writing center efforts for students with disabilities. Because this article describes how to integrate usability/accessibility testing for online and in-person services, it can work as a model for writing centers struggling with the challenges of serving students with disabilities. Toward this end, the article discusses two generations of usability testing on a large, well-established online writing lab (the Purdue OWL), as well as the collaborative projects that emerged between the usability team and campus disabilities services as a result of this testing. The article concludes with heuristics and generative questions that may assist readers in developing similar projects tailored to their own contexts.     

Shape memory polymers as actuators: Characterization of the relevant parameters under constrained recovery

In this work, a shape memory polyurethane is characterized through constrained recovery experiments performed in a tensile testing equipment. The most relevant results obtained are those concerned with the stress released over time during the recovery stage, since they provide quantitative information that can be used in the design of actuators. For this sake, design guidelines are proposed based on the effect of: (i) the programming temperature; (ii) the deformation imposed during the programming stage; (iii) the recovery temperature; and (iv) the manufacturing process used to produce the samples tested (compression molding and Fused Filament Fabrication). The set of experiments performed with compression-molded samples put in evidence a considerable variety of material responses: (i) the maximum released stress varied from 0.74 to 1.68 MPa; (ii) the time required to attain this stress varied from 47 to 600 s; and (iii) the stress was released as a peak value that relaxed rapidly, or, contrarily, had a lasting effect. Another relevant conclusion is that the 3D printing technique does not affect the shape memory behavior of the material. Having this in mind, the conclusions provided by the compression-molded samples study can be extended to printed ones.     

A dynamic model for high temperature polymer electrolyte membrane fuel cells

A dynamic one-dimensional isothermal phenomenological model was developed in order to describe the steady-state and transient behavior of high temperature polymer electrolyte membrane fuel cells (PEMFC). The model accounts for transient species mass transport at the bipolar plates and gas diffusion layers and the electric double layers charge/discharge. To record the impedance spectra, a small sinusoidal voltage perturbation was imposed to the simulator over a wide range of frequencies, and the resultant current density amplitude and phase were recorded.The steady-state behavior of the fuel cell, as well as the impedance spectra were obtained and compared to experimental data of two different fuel cells equipped with different MEAs based on phosphoric acid polybenzimidazole membrane. This approach is new and allows a deeper analysis of the controlling phenomena. The model fitted quite well the I-V curves for both systems, but fairly well the Nyquist plots. The differences observed in the Nyquist plots were attributed to proton resistance in the catalyst layer and the gas diffusion limitations to cross the phosphoric acid layer that coats the catalyst, phenomena not included in the proposed phenomenological model.