Over-limiting Current and Control of Dendritic Growth by Surface Conduction in Nanopores

Understanding over-limiting current (faster than diffusion) is a long-standing challenge in electrochemistry with applications in desalination and energy storage. Known mechanisms involve either chemical or hydrodynamic instabilities in unconfined electrolytes. Here, it is shown that over-limiting current can be sustained by surface conduction in nano pores, without any such instabilities, and used to control dendritic growth during electrodeposition. Copper electrode posits are grown in anodized aluminum oxide membranes with polyelectrolyte coatings to modify the surface charge. At low currents, uniform electroplating occurs, unaffected by surface modification due to thin electric double layers, but the morphology changes dramatically above the limiting current. With negative surface charge, growth is enhanced along the nanopore surfaces, forming surface dendrites and nanotubes behind a deionization shock. With positive surface charge, dendrites avoid the surfaces and are either guided along the nanopore centers or blocked from penetrating the membrane

Overlimiting Current and Shock Electrodialysis in Porous Media

Most electrochemical processes, such as electrodialysis, are limited by diffusion, but in porous media, surface conduction and electro-osmotic flow also contribute to ionic fluxes. In this paper, we report experimental evidence for surface-driven over-limiting current (faster than diffusion) and deionization shocks (propagating salt removal) in a porous medium. The apparatus consists of a silica glass frit (1 mm thick with 500 nm mean pore size) in an aqueous electrolyte (CuSO$_4$ or AgNO$_3$) passing ionic current from a reservoir to a cation-selective membrane (Nafion). The current-voltage relation of the whole system is consistent with a proposed theory based on the electro-osmotic flow mechanism over a broad range of reservoir salt concentrations (0.1 mM - 1.0 M), after accounting for (Cu) electrode polarization and pH-regulated silica charge. Above the limiting current, deionized water ($\approx 10 \mu$ $M$) can be continuously extracted from the frit, which implies the existence of a stable shock propagating against the flow, bordering a depleted region that extends more than 0.5mm across the outlet. The results suggest the feasibility of "shock electrodialysis" as a new approach to water desalination and other electrochemical separations.Comment: 39 pages, 9 fig

Eco-Innovation Indices as Tools for Measuring Eco-Innovation

Measuring eco-innovation helps us understand the overall trends and raises awareness in society. Measuring eco-innovation at the national level and making comparisons across countries may allow us to benchmark performance and foster policy learning. This paper assesses two indices developed in two different regions: The ASEM Eco-Innovation Index (ASEI) by the ASEM SMEs Eco-Innovation Center, based in Republic of Korea; and the Eco-Innovation Scoreboard (Eco-IS) developed by the Eco-Innovation Observatory, based in the European Union. This paper aims to examine and compare the features of both and attempts to obtain insights on their strengths and weaknesses. Towards this aim, our paper assesses those scoreboards against four criteria stemming from innovation analysis: (1) relevance of areas and stakeholders covered; (2) ability to indicate changes; (3) directions towards common goals; and (4) ability to facilitate further changes. We conclude both are promising, despite data shortages, and have great potential to contribute towards the sustainable development goals (SDGs), particularly with regard to the SDGs on sustainable industrialization and sustainable consumption and production. In comparison, the ASEI covers more countries than the Eco-IS. However, the ASEI has limitations on measuring indicators due to limited data availability in Asian countries. The Eco-IS is closely linked with the regional and national policies for eco-innovation in Europe, while the ASEI’s impact appears more limited, as of now. In conclusion, the research results give insights into key areas, goals and applications of eco-innovation indices, and can help upgrading eco-innovation indices. This research helps interpret the scores of two indices better and facilitate application of the scores in the multiple ways. It is expected that this research contributes to developing and modifying a global eco-innovation index and enhancing the ability of these indices to facilitate eco-innovation strategies at national levels and across relevant actors

Heterologous gene expression using self-assembled supra-molecules with high affinity for HSP70 chaperone

Contrary to the results of direct expression, various human proteins (ferritin light-chain, epithermal growth factor, interleukin-2, prepro-ghrelin, deletion mutants of glutamate decarboxylase and arginine deiminase, and mini-proinsulin) were all soluble in Escherichia coli cytoplasm when expressed with the N-terminus fusion of ferritin heavy-chain (FTN-H). Through systematic investigations, we have found that a specific peptide motif within FTN-H has a high affinity to HSP70 chaperone DnaK, and that the peptide motif was composed of a hydrophobic core of three residues (Ile, Phe and Leu) and two flanking regions enriched with polar residues (Gly, Gln and Arg). It was also observed that all the recombinant proteins expressed with the fusion of FTN-H formed spherical nanoparticles with diameters of 10–15 nm, as confirmed by the transmission electron microscopy image. The protein nanoparticles are non-covalently cross-linked supra-molecules formed by the self-assembly function of FTN-H. Upon the formation of the supra-molecule, its size is likely to be limited by the assembly properties of FTN-H, thereby keeping the self-assembled particles soluble. This study reports on the dual function of FTN-H for fusion expression and solubility enhancement of heterologous proteins: (i) high-affinity interaction with DnaK and (ii) formation of self-assembled supra-molecules with limited and constant sizes, thereby avoiding the undesirable formation of insoluble macro-aggregates of heterologous proteins

Body extract of tail amputated zebrafish promotes culturing of primary fin cells from glass catfish

The most spectacular regenerative events in vertebrates are epimorphic regeneration. In this study, interestingly, a whole-body extract 24 h after tail amputation enhanced primary cell growth and viability compared to that of a non-tail amputated body. Additionally, these effects of extract treatment in vitro were dose-dependent occurring at concentrations of 0.02, 0.05 and 0.1 mg/ml. This is the first in vitro study on the interaction between primary fin cells from glass catfish and tail amputated body extracts of zebrafish. These results provide an essential knowledge base for rational approaches to tissue and organ regeneration.Keywords: Cell growth, cell viability, extract, glass catfish, regeneration, zebrafishAfrican Journal of Biotechnology Vol. 12(12), pp. 1449-145

Cell density-dependent differential proliferation of neural stem cells on omnidirectional nanopore-arrayed surface

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Molecular characterization of tetracycline- and quinolone-resistant Aeromonas salmonicida isolated in Korea

The antibiotic resistance of 16 Aeromonas (A.) salmonicida strains isolated from diseased fish and environmental samples in Korea from 2006 to 2009 were investigated in this study. Tetracycline or quinolone resistance was observed in eight and 16 of the isolates, respectively, based on the measured minimal inhibitory concentrations. Among the tetracycline-resistant strains, seven of the isolates harbored tetA gene and one isolate harbored tetE gene. Additionally, quinolone-resistance determining regions (QRDRs) consisting of the gyrA and parC genes were amplified and sequenced. Among the quinolone-resistant A. salmonicida strains, 15 harbored point mutations in the gyrA codon 83 which were responsible for the corresponding amino acid substitutions of Ser83→Arg83 or Ser83→Asn83. We detected no point mutations in other QRDRs, such as gyrA codons 87 and 92, and parC codons 80 and 84. Genetic similarity was assessed via pulsed-field gel electrophoresis, and the results indicated high clonality among the Korean antibiotic-resistant strains of A. salmonicida