The steel–concrete interface

Although the steel–concrete interface (SCI) is widely recognized to influence the durability of reinforced concrete, a systematic overview and detailed documentation of the various aspects of the SCI are lacking. In this paper, we compiled a comprehensive list of possible local characteristics at the SCI and reviewed available information regarding their properties as well as their occurrence in engineering structures and in the laboratory. Given the complexity of the SCI, we suggested a systematic approach to describe it in terms of local characteristics and their physical and chemical properties. It was found that the SCI exhibits significant spatial inhomogeneity along and around as well as perpendicular to the reinforcing steel. The SCI can differ strongly between different engineering structures and also between different members within a structure; particular differences are expected between structures built before and after the 1970/1980s. A single SCI representing all on-site conditions does not exist. Additionally, SCIs in common laboratory-made specimens exhibit significant differences compared to engineering structures. Thus, results from laboratory studies and from practical experience should be applied to engineering structures with caution. Finally, recommendations for further research are made

Proteins and Nucleotide Sequences Involved in DNA Replication of Filamentous Bacteriophage

Filamentous bacteriophages (fd, M13, f1) contain single-stranded circular DNA of about 6400 bases (1). They penetrate the host cell via pili induced by the F-episome of an Escherichia coli cell. During the penetration process their single-stranded genome is converted into double-stranded DNA which is the main viral component in the first minutes after infection. Later in the life cycle, viral single strands are formed and complexed with gene 5 protein. They are assembled in the host membrane into phage particles, which penetrate the cell wall without severe damage of the host. Filamentous phages are quite flexible on the size of the DNA to be packaged. They spontaneously generate miniphages of about 1 kb (2, 3), but they can also comprise artificial DNA sequences up to a length of 15 kb, if the phage packaging signal is provided (4)