Polymerization-induced emission and selective detection to Fe3+/ Fe2+ of triazine-containing polyureas.

In this study, four polyureas with triazine moiety (PUAs) were successfully synthesized through the polymerization of triazine-containing diamine and diisocyanate. The intramolecular aggregation of triazine rings and urea groups along the macromolecular backbone gives PUAs a significant polymerization-induced emission (PIE). Among the four PUAs, PUA-LP shows a significant fluorescent emission at 450 nm, compared to non/weak fluorescent 2,4-diamino-6-phenyl-1,3,5-triazine and L-Lysine diisocyanate ethyl ester monomers. Additionally, the external factors such as solution concentration, excitation wavelength, and precipitants also play a crucial role in the fluorescence of PUAs. As expected, PUA-LP can selectively recognize and detect Fe3+/Fe2+ ions even in the presence of 12 other metal ions and 10 anions. The limit of detection of PUA-LP to Fe3+/Fe2+ is as low as 1.02 µM (0.06 mg/L) and 0.86 µM (0.05 mg/L), respectively, and far below 0.3 mg/L of the allowable national standard for drinking water by WHO. Furthermore, the quenching mechanism of Fe3+/Fe2+ to PUA-LP is attributed to static quenching caused by the coordination of Fe3+/Fe2+ ions with a coordination ratio of 2:1. Based on PIE, the fluorescent PUA-LP was made into an observable and portable testing paper for detecting Fe3+/Fe2+ ions. Finally, we measured the recovery rate of the actual tap water samples and compared the performance of PIE-active PUA-LP with the other reported fluorescent probes to Fe3+/Fe2+ ions.

Common Language Development in Multilingual Contexts: A Study of Russian Language Policy in the Early Years of the Soviet Union.

In the field of Russian linguistics, history, and jurisprudence, the Russian language is widely regarded as a political instrument and, to some extent, reflects the development and influence of contemporary language policy of the Russian language in the Soviet Union. This study aims to examine the process, characteristics, influencing psychological and sociological factors, and consequences of Russian language policy in the early Soviet Union (1917-1930s). Thematic analysis and discourse strategy analysis methods were employed to achieve this goal. The results indicate that a well-thought-out language policy necessitates the establishment of language legislation and a precise legal definition of the status and use of different languages. The absence of language legislation can be a major drawback of language policy. While the Soviet Constitution and other relevant political documents broadly define the status and use of Russian and other languages, there is no specific language legislation regulating the use of each language. Analysis of word frequency statistics demonstrates that the key concepts of Stalinist policy differed compared to the time of Lenin's rule, resulting in a lack of effective legal force and strong mechanisms for controlling language policy practices. As the functional advantages of the Russian language become increasingly evident, some ethnic minorities tend to lean towards studying and using it, leading to the emergence of many bilingual and even trilingual individuals. Other minorities with small or underdeveloped populations turn to the Russian language, which is the most widely spoken language. These findings contribute to the theoretical and practical knowledge base for research in the fields of linguistics, linguistic culturology, history, psycholinguistics, and political science. Subsequent research can focus on current aspects of the country's language policy.

Morpholine-modified polyacrylamides with Polymerization-Induced emission and its specific detection to Cu2+ ions.

In this work, three morpholine-modified polyacrylamide derivatives (MMPAm) were successfully prepared by free radical polymerization of monomers with morpholine moiety. The intramolecular aggregation of morpholine rings on macromolecular backbone gives MMPAm a significant polymerization-induced emission (PIE). Particularly, poly(N-morpholine acrylamide) (PNMPA) has the characteristics of strong fluorescence at 450 nm, and its fluorescence quantum yield reaches 2.87 %. The introduction of morpholine moiety, the length of CH2 spacer between morpholine ring and the backbone and the molecular weight play the important roles in PIE properties of PNMPA. Interestingly, PNMPA can recognize and detect Cu2+ specifically even in the presence of 12 other metal ions by thorough fluorescence quenching, and the detection limit of PNMPA is 17.3 µM. Furthermore, the dynamic quenching of PNMPA by Cu2+ ions and the complexation ratio of 1:2 according to JOB's working diagram were confirmed by fluorescence titration. Under the assistance of EDTA, a reversible detection system for Cu2+ is achieved, and a portable test paper from PNMPA for the detection of Cu2+ was also made. In conclusion, PNMPA is endowed with a significant PIE effect by the intramolecular aggregation of morpholine rings along the backbone in the polymerization of non-fluorescent monomer, and is expected to be a promising material for specific detection to Cu2+ ions.