ISSN:0892-7014    

DOI:10.1080/08927018809378091

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Copper and zinc salts act synergistically and have inhibitory effects on the growth of the diatomsAmphora coffeaeformisandAmphiprora hyalina. The concentrations required to cause a significant reduction in growth yields indicate that the isolates of the two species used are copper and zinc tolerant. Some growth stimulation was found in lower concentrations of the two metals. Cellular levels generally increased with increasing concentrations in the external medium, resulting in increased growth inhibition. Growth yields and cellular copper concentrations were found to be related to calculated cupric ion activities in the medium. Relative inhibitory and cellular concentrations of copper and zinctor A. coffeaeformisandA. hyalinasuggest that the latter species may be more sensitive to CuC12‐2HjO and more tolerant to ZnCl2than the former. The results suggest that inclusion of ZnO as an additional biocide in self‐polishing copolymer antifouling paints would result in more effective antifouling action.

ISSN:0892-7014    

DOI:10.1080/08927018809378092

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

With the aim of establishing the role of interfacial free energy in pellicle formationin vivo, surface free energies of five polymers, dentine and enamel were determined after j, 2 and 48 hours exposure to the oral environment of beagle dogs. After exposure for j hour in the oral cavity of the dogs, the surface free energies of the substrata, originally ranging from 22 to 134 mJ‐m”;2. converged to values between 60 and 100 mJ‐m−2. Thermodynamically this is a very favourable situation, as the solid‐liquid interfacial free energy during exposure is minimal for this range of substratum surface free energies. Changes in the adsorbed protein film most likely occurring during the later stages of the adsorption process, have not been observed from changes in surface free energy. It is therefore concluded that only the initial stages of protein adsorption and pellicle formation are interfacial free energy influenced.

ISSN:0892-7014    

DOI:10.1080/08927018809378093

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

It is generally accepted that in the absence of oxygen corrosion of metals occurs largely due to microbial activity. Sulphate‐reducing bacteria are identified as the single most common causative microorganism responsible for the corrosion process under anaerobic conditions. They are believed to influence the overall process either directly, by consuming cathodic hydrogen (cathodic depolarisation), or indirectly, by producing sulphide as an end product of their metabolism, which then gives rise to cathodically active FeS. Several mechanisms have been proposed to explain the high corrosion rates observed in the field. It is not the author's intention to evaluate these hypotheses, but instead the main aim of this review is to assemble and analyse the literature concerning hydrogen metabolism in sulphate‐reducing bacteria and its role in the anaerobic corrosion process. In recent years evidence has been accumulating that quite clearly demonstrates the importance of hydrogen utilisation from metal surfaces via the hydrogenase enzyme in anaerobic corrosion. Thus, to bring this point to focus, the physiology of sulphate‐reducers is discussed with respect to their ability to consume and produce hydrogen. Also discussed is the recent evidence obtained by several investigators in favour of the cathodic depolarisation hypothesis. Finally, a foundation is laid down for future studies that may help to provide a unifying concept about the very complex process of anaerobic corrosion.

ISSN:0892-7014    

DOI:10.1080/08927018809378094

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The immediate environment of benthic algae is reconsidered in terms of the substratum and the effect this can have on algal distribution, with particular reference to two freshwater ecosystems. Individual species often exhibit marked preferences for particular substrata, such that their presence in the littoral zone of lake systems reflects the type of substratum at different sites, while in a stream system the dynamic interaction between sediment and current velocity determines the substratum distribution and hence, to a large extent, diatom occurrence. In addition to physical differences between sediments, due to grain size, surface features etc., variation in chemical properties also potentially increases the range of contrasting niches for algal colonisation. Thus, different associations can develop within a single water body when contrasting substrata are available, although modifications in methodology may be required to recognise the finer scale patterns. Furthermore, the existence of precise species‐substratum relationships must be taken into account when benthic communities are assessed, particularly in any monitoring or predictive context, e.g. assessment of water‐quality, palaeolimnology etc.

ISSN:0892-7014    

DOI:10.1080/08927018809378095

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Corrosion fatigue is considered to be one of the most important factors in determining the life of static offshore structures such as platforms for oil and gas production; the combination of corrosive environment and cyclic stress can produce failure of metals by the development and growth of cracks. Seawater provides both the chemical reagent and, through wave action, the source of cyclic fatigue loading. Marine fouling can enhance both factors, first by enhancing the corrosive reactions and secondly by increasing the diameter and surface roughness of platform legs and bracing members. In relation to corrosion fatigue this enhancement is mainly due to the production of hydrogen sulphide by sulphate‐reducing bacteria. Both the effects of loading and hydrogen embrittlement can be independent of anti‐corrosion measures and thus need to be quantified and incorporated into the determination of the design life of the structure. Data are presented on the level of hydrogen sulphide that could be found under marine fouling and on corrosion fatigue crack growth in seawater containing various levels of both biologically produced and abiotic hydrogen sulphide. Crack growth rates are found to be enhanced, even at low levels, by hydrogen sulphide, and there are differences between biological and abiological environments.

ISSN:0892-7014    

DOI:10.1080/08927018809378096

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A series of 90/10 cupronickel alloys containing iron at levels between 0% and 5% were immersed in the sea in Chichester Harbour. Samples were retrieved over a 14‐month period and subjected to scanning electron microscopy, energy dispersive X‐ray analysis and X‐ray photoelectron spectroscopy. The alloy with no iron corroded very rapidly and showed little, if any, colonisation. The 0·5% Fe and 1·5% Fe alloys developed microfouling communities dominated by the diatomAmphora, while the 2·5% and 5% Fe‐containing materials showed not only diatoms but also macro‐fouling in the form of barnacle settlement. However, the very loosely adherent nature of the iron and nickel‐rich corrosion products of these high iron alloys resulted in very poor tenacity of adhesion by the macrofouling. However, thick films of diatoms of lower copper tolerance became well established on the iron‐rich alloys. The alternative anti‐fouling mechanisms of the 90/10 copper‐nickels are discussed.

ISSN:0892-7014    

DOI:10.1080/08927018809378097

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Synthetic Adhesives and Sealants, edited by W C Wake. Volume 16 ofCritical Reports on Applied Chemistry, Society of Chemical Industry. John Wiley and Sons, Chichester. 139pp. (£29.25)

ISSN:0892-7014    

DOI:10.1080/08927018809378098

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0892-7014    

DOI:10.1080/08927018809378090

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor