Mine safety assessment is a precondition for ensuring orderly and safety in production. The main purpose of this study was to prevent mine accidents more effectively by proposing a composite risk analysis model. First, the weights of the assessment indicators were determined by the revised integrated weight method, in which the objective weights were determined by a variation coefficient method and the subjective weights determined by the Delphi method. A new formula was then adopted to calculate the integrated weights based on the subjective and objective weights. Second, after the assessment indicator weights were determined, gray relational analysis was used to evaluate the safety of mine enterprises. Mine enterprise safety was ranked according to the gray relational degree, and weak links of mine safety practices identified based on gray relational analysis. Third, to validate the revised integrated weight method adopted in the process of gray relational analysis, the fuzzy evaluation method was used to the safety assessment of mine enterprises. Fourth, for first time, bow tie model was adopted to identify the causes and consequences of weak links and allow corresponding safety measures to be taken to guarantee the mine’s safe production. A case study of mine safety assessment was presented to demonstrate the effectiveness and rationality of the proposed composite risk analysis model, which can be applied to other related industries for safety evaluation.

The toxicity of two natural product antifoulants, capsaicin and zosteric acid, was evaluated using the Microtox assay and a static toxicity test. The EC50 values obtained from the Microtox assay for capsaicin and zosteric acid were 11.75 +/- 1.02 and 442 +/- 100 mg/L, respectively. The static toxicity test, conducted with freshwater organisms, yielded capsaicin EC50 values of 5.5 +/- 0.5 and 23 +/- 2.0 mg/L for P. putida and Lake Erie bacteria, respectively. Zosteric acid EC50 values were 167 +/- 3.9 and 375 +/- 10 mg/L for P. putida and Lake Erie bacteria, respectively. Tests with marine organisms resulted in capsaicin EC50 values of 6.9 +/- 0.2 and 15.6 +/- 0.4 mg/L for V. natriegens and V. parahaemolyticus, respectively; whereas zosteric acid EC50 values were 7.4 +/- 0.1 and 18 +/- 0.6 mg/L for V. natriegens and V. parahaemolyticus, respectively. These results indicate that zosteric acid is much less toxic than capsaicin and that both are substantially less toxic than the currently used antifoulants, such as TBT (EC50< 0.01 ppb). Their effectiveness as natural antifoulants was demonstrated by preliminary attachments studies. As the aqueous antifoulant concentration increased, significant inhibition of bacteria attachment or prevention of biofilm formation was achieved. Hence, both capsaicin and zosteric acid could be attractive alternatives as new antifouling compounds.

No abstract

No abstract

From the attachment study, zosteric acid appeared to be more effective in preventing bacterial attachment when the NPAs were dispersed in the aqueous environment. For practical applications, the antifoulant needs to be incorporated into a coating and have a slow release rate. Thus the ability to successfully incorporate zosteric acid into a coating, without deterring bacterial attachment, needs to be investigated.

No abstract

No abstract

Zosteric acid, a natural product present in eelgrass, has been found to prevent the attachment of some bacteria and barnacles. The results indicate that it may also be effective at reducing the early stages of biofouling, such as the attachment of bacteria that lead to a biofilm. In this study, the ability of zosteric acid in reducing the early stages of fouling was evaluated using attachment studies of fresh water bacteria via two approaches. First, plain coatings were submersed in water containing zosteric acid and either enriched Lake Erie bacteria or Pseudomonas putida, a model fresh water bacteria. It was found that zosteric acid with a concentration one-tenth of its EC 50 (the concentration eliminates 50% of the bacteria) was able to reduce bacterial attachment by more than 90%. The second approach incorporated zosteric acid into silicone coatings in the presence of a common solvent to achieve the slow release of zosteric acid; such coatings were then subjected to the bacterial attachment. A ~75% reduction in bacterial attachment was found for 1 wt% zosteric acid entrapped Sylgard ® 184, a model silicone coating, but the reduction only achieved ~55% for 1 wt% zosteric acid entrapped in a commercial silicone coating, RTV11.