The limit of mass determination with an AFM cantilever-based system

This study was performed in the framework of the Program for Basic Research of State Academies of Sciences for 2013-2020. Shumov I.D. is a recipient of Russian Federation President scholarship for young scientists for 2016-2018 (project identificator SP-4280.2016.4)

One-step synthesis of N-doped graphene in a plasma jet reactor

© Published under licence by IOP Publishing Ltd. The possibility of doping graphene during its synthesis in a plasma jet of nitrogen has been studied. Direct current plasma torch with power of up to 40 kW was used as plasma jet generator. The source of carbon was propane-butane mixture, acetylene or methane. Synthesized materials are characterized by scanning electron microscopy, X-ray photoelectron spectroscopy and thermogravimetric analysis. It has been shown that XPS spectra of graphene flakes produced in nitrogen plasma differ in atomic nitrogen content. The maximum degree of nitrogen doping of graphene was obtained at decomposition of acetylene at 77 Torr

One-step synthesis of N-doped graphene in a plasma jet reactor

© Published under licence by IOP Publishing Ltd. The possibility of doping graphene during its synthesis in a plasma jet of nitrogen has been studied. Direct current plasma torch with power of up to 40 kW was used as plasma jet generator. The source of carbon was propane-butane mixture, acetylene or methane. Synthesized materials are characterized by scanning electron microscopy, X-ray photoelectron spectroscopy and thermogravimetric analysis. It has been shown that XPS spectra of graphene flakes produced in nitrogen plasma differ in atomic nitrogen content. The maximum degree of nitrogen doping of graphene was obtained at decomposition of acetylene at 77 Torr

The Use of Excess Electric Charge for Highly Sensitive Protein Detection: Proof of Concept

In highly sensitive bioanalytical systems intended for the detection of protein biomarkers at low and ultra-low concentrations, the efficiency of capturing target biomolecules from the volume of the analyzed sample onto the sensitive surface of the detection system is a crucial factor. Herein, the application of excess electric charge for the enhancement of transport of target biomolecules towards the sensitive surface of a detection system is considered. In our experiments, we demonstrate that an uncompensated electric charge is induced in droplets of protein-free water owing to the separation of charge in a part of the Kelvin dropper either with or without the use of an external electric field. The distribution of an excess electric charge within a protein-free water droplet is calculated. It is proposed that the efficiency of protein capturing onto the sensitive surface correlates with the sign and the amount of charge induced per every single protein biomolecule. The effect described herein can allow one to make the protein capturing controllable, enhancing the protein capturing in the desired (though small) sensitive area of a detector. This can be very useful in novel systems intended for highly sensitive detection of proteins at ultra-low (≤10−15 M) concentrations

Genomic Analysis of a Hybrid Enteroaggregative Hemorrhagic Escherichia coli O181:H4 Strain Causing Colitis with Hemolytic-Uremic Syndrome

Hybrid diarrheagenic E. coli strains combining genetic markers belonging to different pathotypes have emerged worldwide and have been reported as a public health concern. The most well-known hybrid strain of enteroaggregative hemorrhagic E. coli is E. coli O104:H4 strain, which was an agent of a serious outbreak of acute gastroenteritis and hemolytic uremic syndrome (HUS) in Germany in 2011. A case of intestinal infection with HUS in St. Petersburg (Russian Federation) occurred in July 2018. E. coli strain SCPM-O-B-9427 was obtained from the rectal swab of the patient with HUS. It was determined as O181:H4-, stx2-, and aggR-positive and belonged to the phylogenetic group B2. The complete genome assembly of the strain SCPM-O-B-9427 contained one chromosome and five plasmids, including the plasmid coding an aggregative adherence fimbriae I. MLST analysis showed that the strain SCPM-O-B-9427 belonged to ST678, and like E. coli O104:H4 strains, 2011C-3493 caused the German outbreak in 2011, and 2009EL-2050 was isolated in the Republic of Georgia in 2009. Comparison of three strains showed almost the same structure of their chromosomes: the plasmids pAA and the stx2a phages are very similar, but they have distinct sets of the plasmids and some unique regions in the chromosomes