Disinfection of surfaces by photocatalytic oxidation with titanium dioxide and UVA light

Particularly in microbiological laboratories and areas in intensive medical use, regular and thorough disinfection of surfaces is required in order to reduce the numbers of bacteria and to prevent bacterial transmission. The conventional methods of disinfection with wiping are not effective in the longer term, cannot be standardized, are time- and staff-intensive and use aggressive chemicals. Disinfection with hard ultraviolet C (UVC) light is usually not satisfactory, as the depth of penetration is inadequate and there are occupational medicine risks. Photocatalytic oxidation on surfaces coated with titanium dioxide (TiO2) might offer a possible alternative. In the presence of water and oxygen, highly reactive OH-radicals are generated by TiO2 and mild ultraviolet A (UVA). These radicals are able to destroy bacteria, and may therefore be effective in reducing bacterial contamination. Direct irradiation with UVC however can produce areas of shadow in which bacteria are not inactivated. Using targeted light guidance and a light-guiding sheet (out of a UVA-transmittant, Plexiglas, for example), as in the method described in the present study, bacterial inactivation over the entire area is possible. The effectiveness of the method was demonstrated using bacteria relevant to hygiene such as Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Enterococcus faecium. For these bacteria, a reduction efficiency (RE) more than 6log10 steps in 60 min was observed. Using Candida albicans, a RE of 2log10 steps in 60 min was seen. Light and scanning electron microscopic examinations suggest that the germ destruction achieved takes place through direct damage to cell walls caused by OH-radicals.     

Klimafolgenforschung

Climate Impact Research combines a number of scientific disciplines from natural as well as from economic and social sciences. Integrating methods are developed and used in addition to the various disciplinary ones. New results are produced about climate relevant interactions within an Earth system, which includes human societies. These results point out how to cope with possible negative impacts on societies. That’s not a question of prediction but of perception. It is a question of indicators to perceive critical issues, i.e. vulnerabilities, and to perceive the adaptive capacities of societies to reduce the burdens and hence vulnerabilities in respect to critical impacts of climate change. Examples of how to cope with negative impacts on societies concern the necessity of the conversion of energy systems as well as the improvement of the global water supply.     

Life cycle engineering im Automobilbau

Ecobalance represents the basic principle for an environmental analysis and the starting point for the possibility of achieving improvements. Using the criteria related to both technology and ecology, this method has been expanded upon by IKP/PE and, over the course of many years, has proven to be a satisfactory method for those fields associated with industry and research. Data banks and software systems have been designed and are today applied in industry. An expansion of the holistic balancing to include the ‘social’ dimension is currently being developed by the IKP. Today, ecological decisions in technically and economically-associated areas are continuously being developed which place more emphasis on the preliminary developments than on a purely retrospective analysis. Aside from the continuous, further developments of these types of analysis with regard to never technical questions as well as the integration of newer aspects of optimization based on life cycle information (e.g. production balancing), the goal of further work includes the preparation of process-chain information in the respective in preliminary developments related to the design. The automobile industry consequently plays a significant role here, as was also the case in the initial transformation of methodology which was carried out in the 1990s. Finally, these developments are additionally motivated through the new ordinances presented to be employed throughout the entire EU. The responsibility attributed to a product over the course of its entire lifetime therefore plays a more prominent role. This is also reflected in ordinances like those related to the redemption of old automobiles or in the WEEE of the electronics industry (Directive on Waste Electrical and Electronic Equipment).