An experimental study of cathodic protection for chloride contaminated reinforced concrete

Cathodic protection (CP) is being increasingly used on reinforced concrete structures to protect steel reinforcing bars from corrosion in aggressive conditions. Due to the complexity of environmental conditions, the design specifications in national and international standards are still open to discussion to achieve both sufficient and efficient protection for reinforced concrete structures in engineering practices. This paper reports an experimental research to investigate the influence of chloride content on concrete resistivity, rebar corrosion rate and the performance of CP operation using different current densities. It aims to understand the correlation between the chloride content and concrete resistivity together with the CP current requirement, and to investigate the precision of the CP design criteria in standards

Topological representations of crystal structures: generation, analysis and implementation in the TopCryst system

Main modern approaches to the topological representation of crystal structures of different chemical classes are overviewed. The problem of automated generation and analysis of such representations is discussed, and a new free web service is presented, which enables the user to describe topological features of crystal structures of any complexity and chemical composition in a fully automated mode. The service requires only an input file with crystallographic information in the standard CIF format and generates all reasonable representations of the structure by selecting structural units with rigorous algorithms. Then the representations are assigned to known topological types and relations to other crystal structures, which have to same architectures, are established. The service is interfaced to a set of topological databases, which in turn have gateways to world-wide crystallographic databases. A number of examples of topological analysis of different classes of chemical structures are presented, and an outlook is given for further development and applications of the service for big data analysis and data mining in crystal chemistry and materials science

Purification, characterization, gene cloning and preliminary X-ray data of the exo-inulinase from Aspergillus awamori.

Extracellular exo-inulinase has been isolated from a solid-phase culture of the filamentous fungus Aspergillus awamori var. 2250. The apparent molecular mass of the monomer enzyme was 69 +/- kDa, with a pI of 4.4 and a pH optimum of 4.5. The enzyme hydrolysed the beta-(2-->1)-fructan (inulin) and beta-(2-->6)-fructan (levan) via exo-cleavage, releasing fructose. The values for the Michaelis constants K(m) and V(max) in the hydrolysis of inulin were 0.003 +/- 0.0001 mM and 175 +/- 5 micromol.min(-1).mg(-1). The same parameters in the hydrolysis of levan were 2.08 +/- 0.04 mg/ml and 1.2 +/- 0.02 micromol/min per mg, respectively. The gene and cDNA encoding the A. awamori exo-inulinase were cloned and sequenced. The amino acid sequence indicated that the protein belongs to glycoside hydrolase family 32. A surprisingly high similarity was found to fructosyltransferase from Aspergillus foetidus (90.7% on the level of the amino acid sequence), despite the fact that the latter enzyme is unable to hydrolyse inulin and levan. Crystals of the native exo-inulinase were obtained and found to belong to the orthorhombic space group P2(1)2(1)2(1) with cell parameters a=64.726 A (1A=0.1 nm), b=82.041 A and c=136.075 A. Crystals diffracted beyond 1.54 A, and useful X-ray data were collected to a resolution of 1.73 A