Investigation of the cytotoxicity of silver nitrate and silver-cysteine nanocomplexes

Currently, a large number of studies are devoted to the investigation of the antitumor activity of silver nanoparticles and compounds, one of which is silver nitrate. However, silver nitrate has systemic and local toxic effects. In this work, a method was proposed for the synthesis of non-metallic complexes that do not contain toxic nitrate ions, and the cytotoxicity of silver nitrate and silver-amino acid nanocomplexes was investigated.

[1,2-Bis(diphenylphosphanyl)ethane-κ2 P,P]chlorido(isonicotinamide-κN)palladium(II) nitrate acetonitrile monosolvate

The PdII central atom in the title complex, [PdCl(C26H24P2)(C6H6N2O)]NO3·CH3CN or [PdCl(dppe)(INAM)]NO3·CH3CN, where dppe is 1,2-bis(diphenylphosphanyl)ethane and INAM is isonicotinamide, exists in a slightly distorted square-planar environment defined by the two P atoms of the dppe ligand, a chloride ligand and the N atom of the isonicotinamide pyridyl ring. The crystal packing in the structure is held together by hydrogen bonds between the amide of the INAM ligand and the nitrate ions that complete the outer coordination sphere. A molecule of acetonitrile is also found in the asymmetric unit of the title complex.

Biota communities influence on nutrients circulation in hyporheic zone—a case study in urban spring niches in Bialystok (NE Poland)

Hyporheic zone (HZ) is an interstitial part of groundwater. Complex physical, chemical and biological processes in HZ impact water quality. We hypothesized that groundwater upwelling improves surface water with biogenic compounds in lowland spring niches, and it depends on among others biota communities. The research was conducted in two spring niches in suburbs of Białystok. Interstitial samples were collected with mini-piezometers. In the field, the physical parameters of water were examined, and the micro and macro elements were determined in the laboratory. The analysis of biota included: vascular plants and bryophytes, diatoms, macroinvertebrates and bacteria. The springs studied differed in their richness of organisms, which is associated with varying degrees of abiotic conditions and human transformation. In spring niche with high degree of naturalness were twice less nitrate ions in the surface water than in interstitial water, which indicates the assimilation of nitrate ions by plants growing on the bottom of the niche. Hydrophilic vegetation performs a stabilizing function by assimilating nitrogen compounds and contributing to a variation in nutrients concentration. Groundwater upwelling enrich surface water with DOC and TON. In spring niche No.1 with patches of vegetation, the largest number of macrozoobenthos was recorded. While, the heterogeneous bottom of spring niche No.2 affected the diversity of habitats, and greater biodiversity of benthic fauna. In interstitial waters, there were about twice as few bacteria as in spring waters. Psychrophilic bacteria were present in interstitial waters that influence natural hyporheic processes including circulation of organic matter in the microbiological loop and self-purification of water.

Removal of Nitrate Ions Using Thermally and Chemically Modified Bioadsorbents

Nitrate ions are one of the causes of surface water eutrophication. In the present research, the effective adsorption of nitrate ions (NO3) on bioadsorbents prepared from yam skins (Dioscorea alata) was evaluated. The yam skin was chemically modified with ammonium chloride (NH4Cl), and biochar was prepared from the thermally modified biomass. The results were compared with commercial coal (CC). The bioadsorbents were characterized by SEM-EDS analysis, which showed that the synthesized adsorbents have a heterogeneous surface with pores. The batch adsorption tests showed that the pH has the most significant effect on the NO3 adsorption capacity when using the modified yam skin (MYP), obtaining as best conditions pH 12 and a 0.5 mm particle size with an adsorption capacity of 25.75 mg/g; the best adsorption capacity when using the carbon synthesized from yam skin (CYP) and CC was obtained at pH 2, reaching values of 36 and 33.34 mg/g, respectively. The following performance in terms of adsorption capacity was found: CYP > CC > MYP, according to Langmuir’s model. The equilibrium isotherm of NO3 adsorption on MYP and CYP was adjusted by the Freundlich model, while the Langmuir model described adsorption on CC. The kinetics of all the systems studied showed a good fit to the pseudo-first-order, pseudo-second-order and Elovich models with R2 > 0.95, suggesting a mechanism of chemical adsorption by means of species exchange between the aqueous phase and the surface of the material, with the intervention of an intraparticle diffusion stage; based on these findings, the studied biomasses reached promising adsorption capacities in the removal of nitrate anions, showing that the carbon synthesized from yam skins and modified with ammonium chloride had a remarkable behavior in comparison with commercial carbon and NH4Cl-modified yam skins.

Dynamics of mineral nitrogen compounds in the waters of the Dniester River

This article presents the results of studying the content of mineral (ammonium ions, nitrites and nitrates) and organic nitrogen compounds in water samples collected from the Dniester river in 2020. In the study are examines the seasonal dynamics of the forms of mineral nitrogen, total nitrogen and the correlation between organic and mineral nitrogen. Limits of ammonium ion concentration in the Dniester river varied between 0.002 mg N/l and 0.93 mg N/l, nitrite ions 0.002 mg N/l and 0.05 mg N/l, nitrate ions 0.002 mg N/l - 1.36 mg N/l.