Characterisation of urban aerosol size distribution by radiocarbon and PIXE analyses in a middle-European urban environment for source identification: a pilot study.

This study, conducted in Debrecen, Hungary, aimed to analyse atmospheric particulate matter (APM or PM) through radiocarbon and PIXE analyses during the winter smog (23-25 January) and spring (15-18 May) seasons. The information presented in this pilot study aims to provide insight into the importance of utilising detailed characteristics of the mass size distributions of fossil carbon (ff) and contemporary carbon (fC) content. Additionally, it seeks to compare these characteristics with the size distributions of various elements to enable even more accurate PM source identification. In winter, APM concentrations were 86.27 µg/m3 (total), 17.07 µg/m3 (fC) and 10.4 µg/m3 (ff). In spring, these values changed to 29.5 µg/m3, 2.64 µg/m3 and 7.01 µg/m3, respectively. Notably, differences in mass size distribution patterns were observed between the two seasons, suggesting varied sources for contemporary carbon. Biomass burning emerged as a crucial source during the smog period, supported by similar MMAD (Mass Median Aerodynamic Diameter) values and a strong correlation (r = 0.95, p < 0.01) between potassium and fC. In spring, a significant change in the concentration and distribution of fC occurred, with a broad, coarse mode and a less prominent accumulation mode. Ff was found to have similar distributions as PM, with nearly the same MMADs, during both periods. Finally, a comprehensive comparison of modal characteristics identified specific sources for the various components, including biomass burning, vehicle exhaust, coal and oil combustion, vehicle non-exhaust, road dust, tyre abrasion, mineral dust and biogenic emission. This study showcases how using radiocarbon and PIXE analysis in size distribution data can enhance our understanding of the sources of PM and their effects on different size fractions of PM.

Acid-Catalyzed 1,3-Dipolar Cycloaddition of 2H-Azirines with Nitrones: An Unexpected Access to 1,2,4,5-Tetrasubstituted Imidazoles.

The first 1,3-dipolar cycloaddition of 2H-azirines with nitrones, a straightforward approach toward the regioselective synthesis of 1,2,4,5-tetrasubstituted imidazoles, is reported. This trifluoroacetic acid-catalyzed protocol tolerates a broad range of aliphatic and aromatic substrates, offering an efficient access to highly diverse, multisubstituted imidazoles in isolated yields up to 83% under mild conditions.

1,3-Dipolar Cycloaddition of Isatin-Derived Azomethine Ylides with 2 H-Azirines: Stereoselective Synthesis of 1,3-Diazaspiro[bicyclo[3.1.0]hexane]oxindoles.

A regio- and diastereoselective 1,3-dipolar cycloaddition of 2 H-azirines with azomethine ylides generated in situ from isatins and α-amino acids has been elaborated, affording an unprecedented aziridine-fused spiro[imidazolidine-4,3'-oxindole] framework. This one-pot three-component reaction tolerates a wide range of substrates and enables the construction of highly diverse 1,3-diazaspiro[bicyclo[3.1.0]hexane]oxindoles in isolated yields up to 81% under mild conditions.

Synthesis, cytotoxic characterization, and SAR study of imidazo[1,2-b]pyrazole-7-carboxamides.

The synthesis and in vitro cytotoxic characteristics of new imidazo[1,2-b]pyrazole-7-carboxamides were investigated. Following a hit-to-lead optimization exploiting 2D and 3D cultures of MCF-7 human breast, 4T1 mammary gland, and HL-60 human promyelocytic leukemia cancer cell lines, a 67-membered library was constructed and the structure-activity relationship (SAR) was determined. Seven synthesized analogues exhibited sub-micromolar activities, from which compound 63 exerted the most significant potency with a remarkable HL-60 sensitivity (IC50 = 0.183 µM).

Lewis Acid-Catalyzed Diastereoselective Synthesis of Multisubstituted N-Acylaziridine-2-carboxamides from 2 H-Azirines via Joullié-Ugi Three-Component Reaction.

A ZnCl2-catalyzed diastereoselective Joullié-Ugi three-component reaction from 2 H-azirines, isocyanides, and carboxylic acids was established. The protocol allows the preparation of highly and diversely functionalized N-acylaziridine-2-carboxamide derivatives in up to 82% isolated yields. Moreover, the applicability of N-acylaziridines is demonstrated through a variety of transformations.

One-pot synthesis of diverse N,N'-disubstituted guanidines from N-chlorophthalimide, isocyanides and amines via N-phthaloyl-guanidines.

A sequential one-pot approach towards N,N'-disubstituted guanidines from N-chlorophthalimide, isocyanides and amines is reported. This strategy provides straightforward and efficient access to diverse guanidines in yields up to 81% through previously unprecedented N-phthaloylguanidines. This protocol also features wide substrate scope and mild conditions.