A new toxicity screening test, based on the inhibition of bacterial growth and luciferase activity by toxicants was developed. In the ATP-TOX System, chemical toxicity was found to be time-dependent and increased with increasing exposure time up to 5 hours. Three organisms were evaluated in this study: E. coli K-12 PQ37, Pseudomoms fluorescens and Salmonella typhimurium. E. coli K-12 PQ37 was found to be the most sensitive organism. It was also shown that P. fluorescens was more sensitive to toxicants when grown in minimal medium than in nutrient broth, suggesting that nutrients may have a protective effect on the bacterium. In comparative studies using selected toxic chemicals the ATP-TOX System was found to be more sensitive than the Spirillum uolutans test and comparable to the Microtox test. Toxicant activity in sediment samples was found to be time dependent and increased with increasing exposure time in both ATP-TOX (E. coli) System and Microtox. The ATP-TOX System is complementary to the Microtox test as it also provides indications of low grade toxicant activity which is only manifested in actively growing cells over several life cycles. Thus, the ATP-TOX System appears to be an ideal screening test for sediment toxicity. The data indicate that the ATP-TOX System is sensitive, rapid, reproducible, economical and has great potential in applied studies. ATP-MX SYSTEM1 5 1 can be obtained by establishing the ECSo levels from graphed data, ECm being, in this case, the concentration of toxicant (or ddution of unknown) causing a 50% reduction in light output from the base level.(2) ATP-TOX System Reagents :The ATP-TOX System test was performed using the following bacteria: Pseudomonas fluorescens,'an environmental isolate; Escerichia coli K-12 PQ37 obtained from the SOS Chromotest procedure; and Salmonella typhirnuriurn TA-98 used in Ames' mubgen screening test. Media and reagents used in this procedure are: Nutrient Broth (Bacto-beef extract 3 g, Bacto-peptone 5 g, and 1000 mL distilled water); Minimal Medium, prepared from: KnHPOl 10.5 g, KH2P04 4.5 g, (NH&SO4 1 g, sodium citrate
This paper analyzed the applicable conditions of the Green-Wave traffic theory, used two-phase signal control concept to optimize the Green-Wave traffic theory, put forward specific program for cross intersections and T-intersections. The analysis concluded that the optimized Green-Wave traffic theory is favorable to improve road safety and reduce vehicle fuel consumption and reduce vehicle emissions and other aspects.
Urban open data is the key to the construction of smart city. Through the research on evaluation of urban open data, the concept, types, characteristics and other basic problems of urban open data are systematically summarized. From perspective of "quality", "opening" and "acquisition", a complete urban open data evaluation framework and index system is built. And the corresponding weights of evaluation indexes and score and overall rating methods are determined, so as to objectively evaluate the conditions of urban open data, and describe, monitor, guide and promote the construction and development of urban open data.
In the era of a knowledge economy, lots of requirements, such as innovative talents cultivation, lifelong education, are put forward for the higher education, with the object of endowing the students the ability of succeeding, integrating, and disseminating knowledge, which depends on the establishment of a sustainable ecological environment and a practical platform provided for the students. The paper finds out the concept and connotation of educational ecology, analyzes the rules or principles of high-education ecosystem, discusses the creation of a balanced ecological environment and innovation platform, and summarizes the working and experience of our educational project.
This paper involves an investigation of the relationship between Chinese college students' international posture and their intercultural willingness to communicate (IWTC) by means of questionnaires obtained from 167 Chinese college students. The results of the Pearson correlation show that there is a significant positive relationship between international posture and IWTC. In addition, the results of the multiple linear regressions indicate that Intercultural Friendship Orientation in English learning that is one factor of the international posture can significantly predict students' IWTC.
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