Invisible but Insidious Effects of Microplastics.

Increasing evidence on the adverse health impacts of microplastics (MPs) is available, but their associated risks to the well-being of humans and long-term impacts are poorly understood. An indicator of the remote effects of MPs may be their influence on the rate of aging. To assess the effects of MPs on the aging process, we used accelerated senescence OXYS rats that develop a complex of geriatric diseases.

The development of an analytical procedure for the determination of microplastics in freshwater ecosystems.

Microplastics raise growing concerns regarding their ubiquity and possible negative impact on human health; therefore, the need for comparable, standardized methods is urgent. Modern instrumental analytical techniques, such as IR and Raman spectroscopy, pyrolysis-gas chromatography-mass spectrometry and electron microscopy, are fundamental for the analysis of microplastics in environmental and biological objects. The quality of the samples prepared is a determining factor in the validity of the results obtained.

Pollution of Beach Sands of the Ob River (Western Siberia) with Microplastics and Persistent Organic Pollutants.

Microplastics (MPs) in aquatic environments can be associated with various substances, including persistent organic pollutants, which add to the problem of plastic ecotoxicity. The abundance of 1-5 mm microplastics and concentrations of particle-adsorbed organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in sandy sediments from three beaches in recreational areas along the upper Ob River in Western Siberia were assessed. MP pollution levels in the Ob River beach sands ranged from 24 ± 20.

One-Stage Pathway from Hollongdione to C17-Alkyne and Vinyl Chloride Following Mannich Bases and Carboxylic Acid.

Hollongdione is the first recorded example of the occurrence of a dammarane hexanor-triterpene in nature possessing antiviral and cytotoxic activity. Its simple one-stage transformation into compounds with terminal alkyne and vinyl chloride fragments via the interaction with phosphorus halides is reported. The copper(I)-catalyzed Mannich reaction of 3-oxo-22,23,24,25,26,27-hexanor-dammar-20(21)-in led to a series of aminomethylated products, while 17-carboxylic acid was obtained by ozone oxidation of 3-oxo-22,23,24,25,26,27-hexanor-dammar-20-chloro-20(21)-en ; the following direct amidation of the latter has been developed.

Acid-Catalyzed Condensation of Benzamide with Glyoxal, and Reaction Features.

Scholars from around the world have been attempting to simplify and cheapen the synthetic method for the promising high-energy compound CL-20 for decades. The lack of understanding of the formation mechanisms of hexaazaisowurtzitane derivatives-CL-20 precursors-is a barrier to solving the said problems. Here, we report the results from an in-depth study into the acid-catalyzed condensation between benzamide and glyoxal in a molar ratio of 2:1 in polar protic and aprotic solvents.

The Reactions of 6-(Hydroxymethyl)-2,2-dimethyl-1-azaspiro[4.4]nonanes with Methanesulfonyl Chloride or PPh-CBr.

Activation of a hydroxyl group towards nucleophilic substitution via reaction with methanesulfonyl chloride or PPh-CBr system is a commonly used pathway to various functional derivatives. The reactions of (5(),6())-1-X-6-(hydroxymethyl)-2,2-dimethyl- 1-azaspiro[4.4]nonanes 1- (X = O·; H; OBn, OBz) with MsCl/NR or PPh-CBr were studied.

Multifrequency EPR study of the mobility of nitroxides in solid-state calixarene nanocapsules.

Multifrequency continuous wave (cw) and echo-detected (ED) electron paramagnetic resonance (EPR) was employed to study the mobility of nitroxides confined in nanocapsules. The complexes p-hexanoyl calix[4]arene with 4-methoxy-2,2,6,6-tetramethylpiperidine-N-oxyl (MT) and N-(2-methylpropyl)-N-(1-diethylphosphono-2,2-dimethylpropyl)-aminoxyl (DEPN) were studied by X-, W-band and 360 GHz cw EPR at temperatures between 90 and 370 K. Thereby we were able to extract the canonical values of the hyperfine and g-tensors of the encapsulated radicals as well as information on restricted orientational dynamics of the caged spin probes.

Electron paramagnetic resonance spin trapping of glutathiyl radicals by PBN in the presence of cyclodextrins and by PBN attached to beta-cyclodextrin.

The reaction of the glutathiyl radical (GS*) with a widely used spin trap N- tert-butyl-alpha-phenylnitrone (PBN) has been studied in the presence of various methylated beta-cyclodextrins and with PBN covalently bound to dimethylated beta-cyclodextrin (PBN-DIMEB) and permethylated beta-cyclodextrin (PBN-TRIMEB). Scavenging rate constants for GS* by PBN were obtained in the presence of randomly methylated cyclodextrin (RAMEB) and PBN-TRIMEB and found to be close to the rate constant previously measured for PBN. RAMEB and 2,6-di- O-Me-beta-cyclodextrin (DIMEB) were found to be the most efficient in the increasing PBN/GS* lifetime, by a factor of 5.

Inclusion of 4-methoxy-2,2,6,6-tetramethylpiperidine-N-oxyl in a calixarene nanocapsule in the solid state.

We present an X-ray diffraction (XRD) and multi frequency electron spin resonance (ESR) study of the structure and dynamics of an inclusion complex of p-hexanoyl calix[4]arene (C6OH) with 4-methoxy-2,2,6,6-tetramethylpiperidine-N-oxyl (MT). The single crystal XRD experiments reveal that MT along with ethanol (solvent) molecules are entrapped in a capsular type crystalline lattice of the host C6OH material. ESR measurements were performed at 9.

Mechanistic studies of the reactions of nitrone spin trap PBN with glutathiyl radical.

We performed mechanistic studies of the reaction of PBN with the physiologically relevant glutathiyl radical, GS*, formed upon oxidation of the intracellular antioxidant, glutathione, GSH. The scavenging rate constant of GS* by PBN has been measured directly by laser flash photolysis and indirectly by competitive EPR of the spin adduct of PBN and another spin trap, DMPO (5,5-dimethyl-1-pyrroline N-oxide), and was found to be 6.7 x 107 M(-1) s(-1).

Crystalline inclusion complex of a calixarene with a nitroxide.

The first capsular crystalline inclusion complex of para-hexanoyl calix[4]arene with stable nitroxyl radical DEPN has been isolated and showed a low mobility of the radical in the capsule.