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Summary: Biological invasions are determined by interactions between resident plant communities and exotic plants. Time of invasion and species diversity of resident plant communities may greatly affect exotic plant invasions. We assembled low‐ and high‐diversity resident plant communities by sowing seeds of four and eight grassland species, respectively, and at each of three time periods (1, 4 and 7 weeks after sowing), the resident communities were invaded by Hydrocotyle vulgaris or not. We also constructed a plant community with H. vulgaris alone. Presence of H. vulgaris had no effect on biomass of the resident communities or biomass of each component species. Community age significantly affected biomass and evenness of the resident communities, and their competition with H. vulgaris, but the priority effect of the resident communities was slight. Increasing species richness did not change the interaction between H. vulgaris and the resident plant communities. These findings suggest a weaker competitive exclusionary effect of H. vulgaris on the resident communities with early germination, and H. vulgaris tended to have no significant impact on intact resident terrestrial plant communities. Thus, the potential risk of H. vulgaris invasion is low, especially in the communities with young age. [ABSTRACT FROM AUTHOR]

Abstract: With the development of science and technology, more and more large moving components have been used in industry, and their service lives have become an important issue. After analysis of the previous results, considering the scale factor, a prediction method for fatigue life of large moving components based on the Basquin relation was proposed at first, and then the magnet pole part of motor‐generator rotor was chosen to make simulation parts with different scale factors mainly in terms of their S‐N curves and fractographies. It was found that with the change of specimen scale factor, the stress concentration factor at transition arc is almost unchanged as well as the fatigue strength exponent, and the fatigue strength coefficient changes linearly. Based on those results, a life prediction method was validated, and the results show that this method is a simple but more precise relation. After fatigue fracture surface and crack growth angle observations and quantitative analyses, the fatigue damage mechanisms associated with the relation among fatigue strength exponent and coefficient and scale factors were explained well. Those studies will provide a new clue to the prediction of the service life for those large moving components. [ABSTRACT FROM AUTHOR]

The hot deformation behavior of AISI 316LN austenitic stainless steel was studied through isothermal hot deformation tests conducted on Gleeble 1500 thermo-simulation machine. By using Taguchi method with an L16 (43) orthogonal array, the hot deformation conditions including deformation temperature, strain rate and strain were optimized for obtaining minimum mean grain size of the steel. Analysis of variance was used for determining the effect of the hot deformation parameters on the mean grain size. The results suggested that the strain had the most significant effect on the mean grain size among the three factors. The percent contributions of deformation temperature, strain rate and strain to the mean grain size were 0.80 %, 2.45 % and 93.32 %, respectively. Finally, the confirmation experiment under the optimum conditions, i.e., 1050 °C temperature, 0.01 s-1 strain rate and 0.7 strain was carried out. The observational mean grain size (11.4 μm) is approximately twelve times smaller than that of the initial microstructure. [ABSTRACT FROM AUTHOR]

By using the Taguchi method with an L16 (45) orthogonal array, the conditions of the double loop electrochemical potentiokinetic reactivation (DL-EPR) technique have been optimized to evaluate the different degrees of the precipitates among the sensitized AISI 316LN austenitic stainless steels. The optimum conditions under the highest resolution of DL-EPR were approved to be 1.2 M sulfuric acid, 0.05 M potassium thiocyanate, 0.8 M sodium chloride, 40 mV/min scan rate, and 40 °C. Analysis of variance (ANOVA) was used to determine the effect of the control parameters on the degree of sensitization (DOS) difference. As a result of ANOVA, the sulfuric acid concentration had the most significant effect on the DOS difference among the five factors. The percent contributions of sulfuric acid (H2SO4), potassium thiocyanate (KSCN), sodium chloride (NaCl), scan rate, and temperature to the DOS difference were 53.22, 5.33, 21.74, 4.92, and 14.79%, respectively. Finally, the maximum DOS difference (6.7908) obtained from the confirmation experiment showed an approximate 11 times improvement. [ABSTRACT FROM AUTHOR]

In the field, the growth of the aquatic weed Eichhornia crassipes and the alga Microcystis aeruginosa may be inhibited by fallen leaves of Lantana camara. This study showed that extracts of L. camara leaves and their fractions reduced the biomass of E. crassipes and M. aeruginosa within 7 days under laboratory conditions. Two fractions with highly inhibitory activity from the extract were isolated and subsequently identified as the pentacyclic triterpenoids, lantadene A and lantadene B. Both compounds significantly inhibited E. crassipes and M. aeruginosa growth, even at a low concentration. At all concentrations tested, their inhibitory activities were much higher than that of salicylic acid, a putative allelochemical from L. camara. The results indicated that the predominant allelochemicals involved in L. camara against either E. crassipes or M. aeruginosa are not phenolic acids, but lantadene A and lantadene B. Field trials showed that released levels of lantadene A and lantadene B were significantly correlated with amounts and decomposition periods of L. camara leaves floated in water. The amount released from 5 kg L. camara leaves was over the inhibition threshold of both E. crassipes and M. aeruginosa and reached a maximum at days 15–20. This study suggested that allelochemicals of L. camara could potentially be used to improve the management of weeds and algae in aquatic systems. [ABSTRACT FROM AUTHOR]