Wet-chemical synthesis of enhanced-thermopower Bi1-xSbx nanowire composites for solid-state active cooling of electronics

In 1993, Hicks and Dresselhaus [Thermoelectric figure of merit of a one-dimensional conductor, Phys. Rev. B 47, 16631 (1993).] suggested that Bi nanowires could result in values of the thermoelectric figure of merit zT > 1. The Dresselhaus group also calculated a ternary phase diagram for Bi1-xSbx nanowires as a function of x and wire diameter. This manuscript reports a wet-chemical method to synthesize Bi1-xSbx-silica nanowire composites. Resistivity, Hall electron concentration, electron mobility, Seebeck and Nernst coefficients, and thermal conductivity of composites are measured and compared to bulk polycrystalline Bi1-xSbx samples prepared either by ingot casting or by the same wet chemistry but without nanostructuring. A clear increase of the thermopower in 20-nm Bi94Sb6-silica is reported when compared to bulk samples, and the values are among the highest found in the literature from 300 to 380 K, even though the electron concentration is higher than in the bulk. This suggests that consistent with theory, size quantization is responsible for the thermopower increase

Embracing context: Lessons from designing a dialogue-based intervention to address vaccine hesitancy.

Dialogue with people who are vaccine hesitant has been recommended as a method to increase vaccination uptake. The process of cultivating dialogue is shaped by the context in which it occurs, yet the development of interventions addressing vaccine hesitancy with dialogue often overlooks the role of context and favors relatively fixed solutions. This reflexive paper shares three key lessons related to context for dialogue-based interventions. These lessons emerged during a participatory research project to develop a pilot intervention to create open dialogue among healthcare workers in Belgium about COVID-19 vaccination concerns. Through a mixed methods study consisting of in-depth interviews, focus group discussions, and surveys, we engaged healthcare workers in the design, testing, and evaluation of a digital platform featuring text-based and video-based (face-to-face) interactions. The lessons are: (1) what dialogue means, entails, and requires can vary for a population and context, (2) inherent tension exists between helping participants voice (and overcome) their concerns and exposing them to others' ideas that may exacerbate those concerns, and (3) interactional exchanges (e.g., with peers or experts) that matter to participants may shape the dialogue in terms of its content and form. We suggest that having a discovery-orientation-meaning to work not only inductively and iteratively but also reflexively-is a necessary part of the development of dialogue-based interventions. Our case also sheds light on the influences between: dialogue topic/content, socio-political landscape, population, intervention aim, dialogue form, ethics, researcher position, and types of interactional exchanges

Doubt at the core: Unspoken vaccine hesitancy among healthcare workers.

Funding Information: CG, KP, SD, TK, TN, CVR, LWH report a grant from Fonds Wetenschappelijk Onderzoek (FWO- Research Foundation – Flanders), to conduct social listening of vaccine concerns in Belgium.publishersversionpublishe

Controlled impregnation of multi metal complexes in mesoporous silica

Mesoporous materials are very attractive materials because of their high surface area and therefore used for various applications such as catalyst supports, absorbents, photocatalysts, electrode materials, etc. So far applications of mesoporous materials have mainly been restricted to silica, alumina, titania and carbon, but recently a range of new mesoporous metal oxides have been synthesized. They often possess very interesting properties that differ completely from their bulk counterparts. Although many interesting applications utilizing mesoporous metal oxides may emerge, the synthesis is mostly limited to monometalic oxides. In this research we developed and optimized a synthesis route that can be applied to synthesize various multimetalic oxides. With the aim to synthesize mesoporous SrTiO3 for energy conversion applications, several precursor solutions were synthesized and impregnated into a mesoporous silica template. The influence of the chelating agents, pH and solvent nature on the impregnation efficiency and the quality of the final mesoporous ceramics were investigated. An optimized synthesis route was based on the impregnation of a SrTiO3 percursor solution containing iminodiacetic acid, H2O2 and ethanolamine in a H2O - EtOH mixture. A Sr/Ti ratio of about 1 could be obtained which yielded crystalline mesoporous SrTiO3 after calcination and template removal