Inactivation of the antibacterial and cytotoxic properties of silver ions by biologically relevant compounds

There has been a recent surge in the use of silver as an antimicrobial agent in a wide range of domestic and clinical products, intended to prevent or treat bacterial infections and reduce bacterial colonization of surfaces. It has been reported that the antibacterial and cytotoxic properties of silver are affected by the assay conditions, particularly the type of growth media used in vitro. The toxicity of Ag+ to bacterial cells is comparable to that of human cells. We demonstrate that biologically relevant compounds such as glutathione, cysteine and human blood components significantly reduce the toxicity of silver ions to clinically relevant pathogenic bacteria and primary human dermal fibroblasts (skin cells). Bacteria are able to grow normally in the presence of silver nitrate at >20-fold the minimum inhibitory concentration (MIC) if Ag+ and thiols are added in a 1:1 ratio because the reaction of Ag+ with extracellular thiols prevents silver ions from interacting with cells. Extracellular thiols and human serum also significantly reduce the antimicrobial activity of silver wound dressings Aquacel-Ag (Convatec) and Acticoat (Smith & Nephew) to Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli in vitro. These results have important implications for the deployment of silver as an antimicrobial agent in environments exposed to biological tissue or secretions. Significant amounts of money and effort have been directed at the development of silver-coated medical devices (e.g. dressings, catheters, implants). We believe our findings are essential for the effective design and testing of antimicrobial silver coatings

The Determinants of Gasoline and Diesel Fuel Excise Tax Rates

As Goel and Nelson (1999) show, fluctuations in fuel prices prompt politicians to alter fuel taxation policies. The goal of this paper was to examine the determinants of both gasoline and diesel fuel excise taxes. The diesel model builds on the work of Decker and Wohar (2006) and is extended to construct a model for gasoline fuel excise taxes. In addition to replicating results of prior research, the results suggest that states with colder weather have higher fuel tax rates. Additionally, findings demonstrated that increased funding from the Highway Trust Fund is associated with lower fuel tax rates

A vortex pair near a density-gradient interface

The dynamics of a vortex pair in a stratified atmosphere near a density gradient interface is considered here using direct numerical simulations. The vortex pair is released below the interface and allowed to propagate vertically toward the interface. The results show that strong vortices propagate through the interface without much change in dynamics. Weaker vortices will dissipate energy when they reach the interface and although a remnant of the vortex pair transits the interface, it does not achieve the same altitude that it would have without the interface. Overall, the interface is not a barrier to vortex pairs, but would be expected to change the distribution of energy in more complicated flows

The Quantum Computing Business Ecosystem and Firm Strategies

Quantum computing is an emerging technology that promises to revolutionize business and society. Although it is still in its early stages, firms have begun to invest heavily in the technology. In this article, we review some key themes of quantum computing from a business-oriented perspective, and construct a framework of the quantum computing business ecosystem. We also conduct an analysis of the contemporary discourse to identify four general strategies that firms are following as they invest in quantum computing. We refer to these as conventional, options, discovery, and adversarial strategies and describe and offer examples of each