Chiral ionic liquids (CILs) containing imidazolium cations and L-Proline (L-Pro) anions were applied as chiral selector to separate tryptophan (Trp) enantiomers on a C18 column by ligand exchange chromatography. Sever...Chiral ionic liquids (CILs) containing imidazolium cations and L-Proline (L-Pro) anions were applied as chiral selector to separate tryptophan (Trp) enantiomers on a C18 column by ligand exchange chromatography. Several factors influencing Trp enantiomers separation, such as alkyl chain length of CILs, concentrations of Cu2+ and CILs, pH of the mobile phase, flow rate, organic solvent and temperature, were studied. Under the optimal conditions, the Trp enantiomers could be successfully separated within 21 min with the resolution of 2.30. At the same time, some thermodynamical parameters were obtained. The experimental results show that the enthalpy values of the Trp enantiomers are negative, indicating that the separation process is exothermic. And the enthalpy values of D-Trp are larger than those of L-Trp, which indicates that L-Trp could form more stable ternary complexes with tryptophan enantiomers.展开更多
The condition and physical sense of actual dynamic user optimum are explained by analyzing a simple road network route choice. To match the practical application requirements, assignment network and simulation network...The condition and physical sense of actual dynamic user optimum are explained by analyzing a simple road network route choice. To match the practical application requirements, assignment network and simulation network are classified account for varying flowing loading. Instantaneous dynamic user optimum model should be applied to the former and actual dynamic user optimum model the latter respectively. The two model’s feasibility is studied as well. Considering the application in ATMS, the model is mainly used to analyze the altering OD problem. Moreover, it adds the method of route adapting into the object function selection to appraise elastic trip strategy and set up real means of route inducement.展开更多
Because of the anonymity and openness of E-commerce, the on-line transaction and the selection of network resources meet new challenges. For this reason, a trust domain-based multi-agent model for network resource sel...Because of the anonymity and openness of E-commerce, the on-line transaction and the selection of network resources meet new challenges. For this reason, a trust domain-based multi-agent model for network resource selection is presented. The model divides the network into numbers of trust domains and prevents the inconsistency of information maintained by different agents through the periodical communication among the agents. The model enables consumers to receive the response from the agents much quicker because the trust values of participators are evalUated and updated dynamically and timely after the completion of each transaction. In order to make users choose the best matching services and give users with trusted services, the model takes into account the similarity between services and the service providers＇ recognition to the services. Finally, the model illustrates the effectiveness and feasibility according to the experiment.展开更多
Although the majority of studies on mate choice focus on female mate choice, there is growing recognition of the role of male mate choice too. Male mate choice is tightly linked to 2 other phenomena： female competiti...Although the majority of studies on mate choice focus on female mate choice, there is growing recognition of the role of male mate choice too. Male mate choice is tightly linked to 2 other phenomena： female competition for males and ornamentation in females. In the current article, I review the existing literature on this in a group of fishes, Poeciliidae. In this group, male mate choice appears to be based on differences in female quality, especially female size, which is a proxy for fecundity. Some males also have to choose between heterospecific and conspecific females in the unusual mating system of the Amazon molly. In this case, they typically show a preference for conspecific females. Whereas male mate choice is relatively well documented for this family, female ornamentation and female competition are not.展开更多
The term ＇assortative mating＇ has been applied to describe two very different phenomena： （1） the tendency for indi- viduals to choose phenotypically similar mates from among conspecifics; or （2） the tendency to...The term ＇assortative mating＇ has been applied to describe two very different phenomena： （1） the tendency for indi- viduals to choose phenotypically similar mates from among conspecifics; or （2） the tendency to prefer conspecific over hete- rospecific mates （behavioral reproductive isolation）. Both forms of assortative mating are widespread in nature, but the relation- ship between these behaviors remains unclear. Namely, it is plausible that a preference for phenotypically similar conspecifics in cidentally reduces the probability of mating with phenotypically divergent heterospecifics. We present a model to calculate how the level of reproductive isolation depends on intraspecific assortative mating and the phenotypic divergence between species. For empirically reasonable levels of intraspecific assortment on a single trait axis, we show that strong reproductive isolation requires very substantial phenotypic divergence. We illustrate this point by applying our model to empirical data from threespine stickleback Gasterosteus aculeatus and Darwin＇s Finches （Geospiza spp）. We conclude that typical levels of intraspecific assortment cannot generally be extrapolated to explain levels of interspecific reproductive isolation. Instead, reproductive isolation between species likely arises from different mate choice behaviors, or multivariate assortative mating [Current Zoology 58 （3）： 484-492, 2012].展开更多
Mating decisions can be affected by intrasexual competition and sensitive to operational sex-ratio （OSR） changes in the population. Conceptually, it is assumed that both male and female matecompetition may interfere...Mating decisions can be affected by intrasexual competition and sensitive to operational sex-ratio （OSR） changes in the population. Conceptually, it is assumed that both male and female matecompetition may interfere with female reproductive decisions. Experimentally, however, the focus has been on the effect of male competition on mate choice. In many species with paternal care as in the common goby Pomatoschistus microps, the OSR is often female-biased and female matecompetition for access to available nesting males occurs. Using the same protocol for 3 experi- ments testing the effect of a perceived risk of female mate-competition, I studied female preferences for nest-holding males differing in its nest size （large/small）, body size （large/small）, and nest status （with/without eggs already in nest） and measured mating decisions, spawning latencies, and clutch size. Regardless of the social context, females preferred males with larger nests. A preference for large males was only expressed in presence of additional females. For nest status, there was a tendency for females to prefer mating with males with an empty nest. Here, female-female competition increased the propensity to mate. The results of this study show that females are sensitive to a female competitive social environment and suggest that in choice situations, females respond to the social context mainly by mating decisions per se rather than by adjusting the clutch size or spawning latency. Females base their mating decisions not only on a male＇s nest size but also on male size as an additional cue of mate quality in the presence of additional females.展开更多
基金Project(21176262) supported by the National Natural Science Foundation of ChinaProject(2010WK3029) supported by Science and Technology Program of Hunan Province,China
文摘Chiral ionic liquids (CILs) containing imidazolium cations and L-Proline (L-Pro) anions were applied as chiral selector to separate tryptophan (Trp) enantiomers on a C18 column by ligand exchange chromatography. Several factors influencing Trp enantiomers separation, such as alkyl chain length of CILs, concentrations of Cu2+ and CILs, pH of the mobile phase, flow rate, organic solvent and temperature, were studied. Under the optimal conditions, the Trp enantiomers could be successfully separated within 21 min with the resolution of 2.30. At the same time, some thermodynamical parameters were obtained. The experimental results show that the enthalpy values of the Trp enantiomers are negative, indicating that the separation process is exothermic. And the enthalpy values of D-Trp are larger than those of L-Trp, which indicates that L-Trp could form more stable ternary complexes with tryptophan enantiomers.
文摘The condition and physical sense of actual dynamic user optimum are explained by analyzing a simple road network route choice. To match the practical application requirements, assignment network and simulation network are classified account for varying flowing loading. Instantaneous dynamic user optimum model should be applied to the former and actual dynamic user optimum model the latter respectively. The two model’s feasibility is studied as well. Considering the application in ATMS, the model is mainly used to analyze the altering OD problem. Moreover, it adds the method of route adapting into the object function selection to appraise elastic trip strategy and set up real means of route inducement.
基金Supported by the National Natural Science Foundation of China （No. 60873203 ）, the Natural Science Foundation of Hebei Province （No F2008000646） and the Guidance Program of the Department of Science and Technology in Hebei Province （No. 72135192）.
文摘Because of the anonymity and openness of E-commerce, the on-line transaction and the selection of network resources meet new challenges. For this reason, a trust domain-based multi-agent model for network resource selection is presented. The model divides the network into numbers of trust domains and prevents the inconsistency of information maintained by different agents through the periodical communication among the agents. The model enables consumers to receive the response from the agents much quicker because the trust values of participators are evalUated and updated dynamically and timely after the completion of each transaction. In order to make users choose the best matching services and give users with trusted services, the model takes into account the similarity between services and the service providers＇ recognition to the services. Finally, the model illustrates the effectiveness and feasibility according to the experiment.
文摘Although the majority of studies on mate choice focus on female mate choice, there is growing recognition of the role of male mate choice too. Male mate choice is tightly linked to 2 other phenomena： female competition for males and ornamentation in females. In the current article, I review the existing literature on this in a group of fishes, Poeciliidae. In this group, male mate choice appears to be based on differences in female quality, especially female size, which is a proxy for fecundity. Some males also have to choose between heterospecific and conspecific females in the unusual mating system of the Amazon molly. In this case, they typically show a preference for conspecific females. Whereas male mate choice is relatively well documented for this family, female ornamentation and female competition are not.
文摘The term ＇assortative mating＇ has been applied to describe two very different phenomena： （1） the tendency for indi- viduals to choose phenotypically similar mates from among conspecifics; or （2） the tendency to prefer conspecific over hete- rospecific mates （behavioral reproductive isolation）. Both forms of assortative mating are widespread in nature, but the relation- ship between these behaviors remains unclear. Namely, it is plausible that a preference for phenotypically similar conspecifics in cidentally reduces the probability of mating with phenotypically divergent heterospecifics. We present a model to calculate how the level of reproductive isolation depends on intraspecific assortative mating and the phenotypic divergence between species. For empirically reasonable levels of intraspecific assortment on a single trait axis, we show that strong reproductive isolation requires very substantial phenotypic divergence. We illustrate this point by applying our model to empirical data from threespine stickleback Gasterosteus aculeatus and Darwin＇s Finches （Geospiza spp）. We conclude that typical levels of intraspecific assortment cannot generally be extrapolated to explain levels of interspecific reproductive isolation. Instead, reproductive isolation between species likely arises from different mate choice behaviors, or multivariate assortative mating [Current Zoology 58 （3）： 484-492, 2012].
文摘Mating decisions can be affected by intrasexual competition and sensitive to operational sex-ratio （OSR） changes in the population. Conceptually, it is assumed that both male and female matecompetition may interfere with female reproductive decisions. Experimentally, however, the focus has been on the effect of male competition on mate choice. In many species with paternal care as in the common goby Pomatoschistus microps, the OSR is often female-biased and female matecompetition for access to available nesting males occurs. Using the same protocol for 3 experi- ments testing the effect of a perceived risk of female mate-competition, I studied female preferences for nest-holding males differing in its nest size （large/small）, body size （large/small）, and nest status （with/without eggs already in nest） and measured mating decisions, spawning latencies, and clutch size. Regardless of the social context, females preferred males with larger nests. A preference for large males was only expressed in presence of additional females. For nest status, there was a tendency for females to prefer mating with males with an empty nest. Here, female-female competition increased the propensity to mate. The results of this study show that females are sensitive to a female competitive social environment and suggest that in choice situations, females respond to the social context mainly by mating decisions per se rather than by adjusting the clutch size or spawning latency. Females base their mating decisions not only on a male＇s nest size but also on male size as an additional cue of mate quality in the presence of additional females.
