Moisture Buffer Value of Building Materials

Building materials and furnishing used in contact with indoor air may have a positive effect to moderate the variations of indoor humidity seen in occupied buildings. Thus, very low humidity can be alleviated in winter, as well as can high indoor humidity in summer and during high occupancy loads. This way, materials can be used as a passive means of establishing indoor climatic conditions, which are comfortable for human occupancy, or for safe storing of artefacts which are sensible to humidity variation. But so far there has been a lack of a standardized figure to characterize the moisture buffering ability of materials. It has been the objective of a recent (ongoing until mid-2005) Nordic project to come up with such a definition, and to declare it in the form of a NORDTEST method. Apart from the definition of the term Moisture Buffer Value, there will also be a declaration of a test protocol which expresses how materials should be tested. Finally as a part of the project, some Round Robin Tests will be carried out on various typical building materials. The paper gives an account on the definition of the Moisture Buffer Value, it will outline the content of the test protocol, and it will give some examples of results from the Round Robin Tests

Expression of double Vitreoscilla hemoglobin enhances growth and alters ribosome and tRNA levels in Escherichia coli

In several organisms, expression of a gene encoding dimeric hemoglobin (VHb) from the obligate aerobic bacterium Vatreoscilla stercoraria has been shown to increase microaerobic cell growth and enhance oxygen-dependent cell metabolism. In an attempt to further improve these effects of VHb, a gene encoding two vhb genes connected by a short linker of six base pairs was constructed and expressed in Escherichia cola (double VHb). Escherichia cola cells expressing double VHb reached a cell density 19% higher than that of cells expressing native VHb. The protein production per cell remained constant since the increase in cell growth was accompanied by an increase in protein content by 16%. Investigation of ribosome and tRNA content revealed that cells expressing double VHb reached their maximal capacity of protein synthesis later during cultivation than cells expressing native VHb, and furthermore they reached considerably higher levels of ribosome and tRNA compared to that of the VHb-expressing cells