When droplets coalesce on a superhydrophobic nanostructured surface, the resulting droplet can jump from the surface due to the release of excess surface energy. If designed properly, these superhydrophobic nanostructured surfaces can not only allow for easy droplet removal at micrometric length scales during condensation but also promise to enhance heat transfer performance. However, the rationale for the design of an ideal nanostructured surface as well as heat transfer experiments demonstrating the advantage of this jumping behavior are lacking. Here, we show that silanized copper oxide surfaces created via a simple fabrication method can achieve highly efficient jumping-droplet condensation heat transfer. We experimentally demonstrated a 25% higher overall heat flux and 30% higher condensation heat transfer coefficient compared to state-of-the-art hydrophobic condensing surfaces at low supersaturations (<1.12). This work not only shows significant condensation heat transfer enhancement but also promises a low cost and scalable approach to increase efficiency for applications such as atmospheric water harvesting and dehumidification. Furthermore, the results offer insights and an avenue to achieve high flux superhydrophobic condensation.

Vapor condensation is routinely used as an effective means of transferring heat, with dropwise condensation exhibiting a 5 -7x heat transfer improvement compared to filmwise condensation.However, state-of-the-art techniques to promote dropwise condensation rely on functional hydrophobic coatings, which are often not robust and therefore undesirable for industrial implementation. Natural surface contamination due to hydrocarbon adsorption, particularly on noble metals, has been explored as an alternative approach to realize stable dropwise condensing surfaces. While noble metals are prohibitively expensive, the recent discovery of robust rare earth oxide (REO) hydrophobicity has generated interest for dropwise condensation applications due to material costs approaching 1% of gold; however, the underlying mechanism of REO hydrophobicity remains under debate. In this work, we show through careful experiments and modeling that REO hydrophobicity occurs due to the same hydrocarbon adsorption mechanism seen previously on noble metals. To investigate adsorption dynamics, we studied holmia and ceria REOs, along with control samples of gold and silica, via X-Ray photoelectron spectroscopy (XPS) and dynamic time-resolved contact angle measurements. The contact angle and surface 2 carbon percent started at ≈ 0 on in-situ argon-plasma-cleaned samples and increased asymptotically over time after exposure to laboratory air, with the rare earth oxides displaying hydrophobic (> 90 degrees) advancing contact angle behavior at long times (> 4 days). The results indicate that REOs are in fact hydrophilic when clean, and become hydrophobic due to hydrocarbon adsorption. Furthermore, this study provides insight into how REOs can be used to promote stable dropwise condensation, which is important for the development of enhanced phase change surfaces. However, the longevity of these ultra-thin coatings remains a question due to the lack of extended or accelerated testing to assess mechanical durability and long-term stability. KEYWORDS:An alternative to the direct application of low-surface-energy coatings relies on surface contamination due to energetically favorable hydrocarbon adsorption, particularly on high thermal conductivity noble metals (i.e., gold and silver). 7 These metals are wetting when clean, but reduce their surface energy by adsorbing hydrocarbons from air, enabling dropwise condensation when used as condenser surfaces. The robustness of this approach is welldocumented, with one paper demonstrating continuous dropwise condensation on gold for over five years in a closed system. 8 Unfortunately, the high price of noble metals prohibits this approach in practice.Researchers have recently demonstrated rare earth oxides (REOs) as potential candidates for condenser surface coatings due the their apparent intrinsic hydrophobicity 9 and costs approaching 1% of gold. 10 However, reported contact angles on REOs are inconsistent. 4Advancing contact angles ranging from 17 -134° have been observed, with a study reporting...

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This paper analyses the impact of the use of electronic resources and Health InterNetwork Access to Research Initiative (HINARI) services for medical research libraries in Bangladesh, emphasising the International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b). Purposeful use of e-resources, time and cost-saving benefits, research impact, and challenges of using HINARI are discussed. The basic study was conducted at icddr,b in January–February 2014, using a mixed methodology, combining qualitative and quantitative approaches, including a background literature review, usage data shared from the HINARI secretariat at the World Health Organization (WHO), questionnaires, personal observations, and interviews with staff members of icddr,b. Findings revealed that icddr,b is the heaviest user of HINARI (a major source of public health and medical e-resources) in Bangladesh, with demonstrable increases of health research journal articles after introducing HINARI in 2003.

Abstract.We provide an overview of the impact of using nanostructured surfaces to improve the performance of solar thermophotovoltaic (STPV) energy conversion and condensation systems. We demonstrated STPV system efficiencies of up to 3.2%, compared to ≤1% reported in the literature, made possible by nanophotonic engineering of the absorber and emitter. For condensation systems, we showed enhanced performance by using scalable superhydrophobic nanostructures via jumping-droplet condensation. Furthermore, we observed that these jumping droplets carry a residual charge which causes the droplets to repel each other mid-flight. Based on this finding of droplet residual charge, we demonstrated electric-field-enhanced condensation and jumping-droplet electrostatic energy harvesting.