An Intramolecular Schmidt Reaction of δ-Azido N-Acylbenzotriazoles.

A Lewis acid promoted intramolecular Schmidt reaction of N-acylbenzotriazoles with alkyl azides was designed and realized. The benzotriazole was not only employed as an efficient activator for initiating the Schmidt rearrangement but also used as a powerful terminator for the subsequent nucleophilic trapping of the isocyanate ion and/or N-acyliminium ion from the rearrangement. Thirteen δ-azido N-acylbenzotriazoles were investigated, and the conversion afforded the desired benzotriazole-1-carboxamides and lactams with good to excellent yields.

[Mechanisms and Efficiencies of Removal of PPCPs by Pilot River Water Bypass Treatment Process].

The pharmaceuticals and personal care products (PPCPs) released into urban rivers are triggering certain ecological risks. The current study investigated the removal efficiencies of 30 frequently detected PPCPs by two river water bypass treatment processes (CS-BAF-UF-Ozone and CS-MBR-Ozone), and investigated the removal mechanism and eco-toxicological risk variation of target compounds via section-removal investigation and risk quotient model, respectively. Results indicated that both processes could efficiently remove the target PPCPs; the removal rates of tetracyclines and caffeine were>90% in the biological sections, while sulfonamides, fluoroquinolones, and other pharmaceuticals could only be efficiently removed when the COD of the influent and the water temperature were comparatively higher; the ozone process had particular effect on removing these compounds. The cumulative removal rate of all PPCPs during the whole process was higher than 92.5%. The total risk quotient (RQtot) of target PPCPs could be efficiently reduced by the bypass treatment processes; the RQtot decreased from 12.6 in the influent river water to 0.2 in the ozone effluent, with a removal rate of 98.4%.

A simple method to detect the heterogeneity of nucleotide substitution processes by measuring asymmetry in paired comparison.

A simple method is presented, which uses a chi2 statistic to measure asymmetry of the substitution matrix between two DNA sequences in order to test a homogeneity hypothesis of the substitution processes. In theory, this chi2 test holds irrespective of whether there is among-site (i) heterogeneity in substitution rates, (ii) correlation in evolutionary rates/models, and (iii) variation in substitution models. Computer simulations showed that the chi2 test is powerful under a variety of models of sequence evolution. Comparison of the eleven sequenced arthropod mtDNAs by using this test revealed that most of the observed evolutionary models were homogeneous between the two mosquitoes but not between Daphnia pulex or Artemia franciscan and the other arthropods, probably due to shifts to a high AT content. A comparison to Kumar and Gadagkar's test by computer simulation as well as empirical data analysis is also given.