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Free-standing, composite hydrogels containing the visible-light responsive metal-free semiconductor graphitic carbon nitride (g-C3N4) as an integral component have been fabricated by direct casting...

In this manuscript, we describe the fabrication of photoactive biocidal or sporicidal films from urea-derived graphitic carbon nitride (u-g-C3N4). Co-deposited films of u-g-C3N4 and Escherichia coli O157:H7 (IC50 = 14.1 ± 0.2 mJ) or Staphylococcus aureus (methicillin resistant IC50 = 33.5 ± 0.2 mJ, methicillin sensitive IC50 = 42.7 ± 0.5 mJ) demonstrated significantly enhanced bactericidal behavior upon administration of visible radiation (400 nm ≤ λ ≤ 426 nm). In all cases, complete eradication of the microbial sample was realized upon administration of 100 mJ of visible radiation, while no antimicrobial activity was observed for non-irradiated samples. In contrast, Bacillus anthracis endospores were more resistant to u-g-C3N4 mediated killing with only a ca. 25% reduction in spore viability when treated with a 200 mJ dose of visible radiation. Characterization of u-g-C3N4 reveals that the improved activity results from enhancements of both the surface area and reduction potential of the material’s conduction band edge, coupled with fast injection of charge carriers into localized states and a decline in radiative recombination events. The results of this study demonstrate that g-C3N4-based materials offer a viable scaffold for the development of new, visible light driven technologies for controlling potentially pathogenic microorganisms.

Photoactive films derived from nanostructured samples of metal-free, intermediate band gap semiconductor graphitic carbon nitride (ns-g-C3N4) have been synthesized and characterized for their particle properties and antimicrobial activity. Physical characterization reveals that these materials are composed of discrete nanoparticles whose dimensions range from 200 nm to 700 nm. Investigation of the photochemical reactivity of ns-g-C3N4 using coumarin-3-carboxylic acid (3-CCA) indicates that this material produces reactive oxygen species (ROS) under visible radiation. When irradiated with 0.31 J visible light, ns-g-C3N4-based materials reduced the viability of both Gram-negative Escherichia coli O157:H7 and Gram-positive Staphylococcus aureus by approximately 50%. Nearly complete inactivation of both strains of microorganisms was achieved upon administration of a 0.62 J dose of visible radiation. Importantly, no biocidal activity was observed for non-irradiated samples, indicating that the g-C3N4-derived films are not inherently toxic in the absence of visible light. The results of this study suggest that materials and, by extention, films and coatings derived from g-C3N4 may present a novel route for controlling pathogenic microorganisms on surfaces in the environment, and could be useful in reducing incidents of hospital-acquired infections.

The Faculty of Accident and Emergency Medicine was inaugurated on 2 November 1993. The new council decided that it would like a logo or badge to signify its identity and to adorn such items as headed notepaper and the president's badge of office. As registrar I was instructed to approach the College of Arms for letters-patent granting the faculty its own coat of arms. Because of the multidisciplinary nature of accident and emergency medicine, the faculty is an intercollegiate one based on six royal colleges. The faculty has flourished, it has a steadily increasing membership, and the faculty board's examination committee holds regular examinations for fellowship of the faculty twice a year. The first step was to approach the College of Arms in London and the duty herald, who in our case was William Hunt, Portcullis Pursuivant of Arms. He led me through the detailed process of acquiring our armorial bearings. We submitted the articles of constitution of the faculty to Portcullis, who submitted them to the Kings of Arms. The faculty was then given permission to petition the Earl Marshal for armorial bearings. Portcullis had made it clear that the smaller the committee designing the coat of arms the better. He favoured a committee of one. In the event we formed a small subcommittee of three. Figure 1 shows the principal elements of an achievement of arms, in this case those of the Worshipful …

The gap between industry and education should be a cause of concern to both sides. Employers too often see the gap as the failure of the education system to meet the needs of employment. This narrow view, however, is both arrogant and lacking in an appreciation of the full extent of the problem. It takes two sides to create a gap and in this case industry must accept its share of blame for the poor co‐operation and understanding which exists between education and the world of work.

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The Working Mathematics Group, a voluntary body which works on a shoestring budget mostly raised its own efforts, has a proud record of achievement. Yet it looks like moving into a crisis condition towards the end of this year for lack of financial support. While this is happening the MSC is proposing to invade the field of preparing open learning materials by some sort of bureaucratic system to be paid for out of public funds. In this journal, in our Phoenix Series, we argue that what is required is the reverse of this situation: we need to harness local effort, and voluntary effort, especially when it happens also to be expert effort, in the service of the community — a feature which WMG illustrates to perfection — and move away from organising everything from the centre by highly‐paid career bureaucrats in the manner of the MSC and the Ministries. Now read the inside story from the point of view of the WMG. One lesson is that the disbursement of funds from the public purse to the various agents working to restore the country's prosperity is not really co‐ordinated by any part of the system: one Ministry seems not to know what the others are doing in areas of mutual interest and responsibility. Another lesson is that surely voluntary bodies, with their economical way of working, their ability to address themselves to real problems and their capacity to draw on a corps of dedicated workers giving their services free, should be protected from being driven out of business by the civil service empire builders. (Editor)