OPTIMIZATION OF THE TECHNOLOGICAL SCHEME FOR THE PRODUCTION OF PREPARATIONS FOR GENE DIAGNOSTICS OF PARTICULARLY DANGEROUS INFECTIOUS DISEASES USING POLYMERASE CHAIN REACTION WITH HYBRIDIZATION-FLUORESCENT REGISTRATION OF RESULTS

Objective of the study was to optimize technological scheme for the production of preparation for gene diagnostics of plague with hybridization-fluorescent registration (HFR) of results, which is associated with the assessment and selection of synthesis conditions and method of oligonucleotide probe purification included into the kit and carrying fluorophore (6-carboxyfluorescein) and quencher (Black Hole Quencher-1) tags, as well as to evaluate their properties and implement this new technological line into manufacturing.Materials and methods. The object of investigation was the reagent panel “Gene Yersinia pestis Identification-HFR” and its constituent elements, probes and primers, providing for hmsH gene amplification. Synthesis of the primers and probes was carried out in 8-well DNA synthesizer ASM-800 (Bioset, Russia), using solid phosphite amid method. For the experiments the probes obtained were purified either by means of electrophoresis in 20 % polyacrylamide gel (size 20×20) or (size 8×10) with further purification through RP-cartridges in semi-automated mode in OPS-201 system and manually, or on RP-cartridges only in manual mode; or applying highperformance liquid chromatography (HPLC). Specific activity of the produced probes was tested by polymerase chain reaction using the DNA isolated from bacterial suspensions of Yersinia pestis C-624 strain, in concentrations up to 1·103 – 1·106 mc/ml.Results and conclusions. Optimized has been synthesis technology; selected has been the method for oligonucleotide probe purification, carrying phluorophore-6-carboxyphluorescin and Black Hole Quencher-1. Demonstrated is viability of applying the stated oligonucleotides or HPLC, or electrophoresis in 20 % polyacrylamide gel with 7 M urea and further purification through RP-cartridges in manual mode for purification purposes. Introduction of the optimized technological scheme in manufacturing of preparations for gene indication and identification of particularly dangerous pathogens with hybridization-fluorescent detection will allow for the reduction of lead time by 50 % and original cost – by 66 %

Minimum Conductivity and Evidence for Phase Transitions in Ultra-clean Bilayer Graphene

Bilayer graphene (BLG) at the charge neutrality point (CNP) is strongly susceptible to electronic interactions, and expected to undergo a phase transition into a state with spontaneous broken symmetries. By systematically investigating a large number of singly- and doubly-gated bilayer graphene (BLG) devices, we show that an insulating state appears only in devices with high mobility and low extrinsic doping. This insulating state has an associated transition temperature Tc~5K and an energy gap of ~3 meV, thus strongly suggesting a gapped broken symmetry state that is destroyed by very weak disorder. The transition to the intrinsic broken symmetry state can be tuned by disorder, out-of-plane electric field, or carrier density

Spatially Resolved On-Chip Picosecond Pulse Detection Using Graphene

We present an on-chip time domain terahertz (TD-THz) system in which picosecond pulses are generated in low-temperature-grown gallium arsenide (LT-GaAs) and detected in graphene. The detected pulses were found to vary in amplitude, full width at half maximum (FWHM), and DC offset when sampled optically at different locations along a 50-μm-long graphene photoconductive (PC) detector. The results demonstrate the importance of detection location and switch design in graphene-based on-chip PC detectors

Approaches to Optimization of Oligonucleotide Synthesis during Manufacturing of Preparations for Gene Diagnostics of Particularly Dangerous Infectious Diseases

Objective of the study is to investigate the impact of activator, oxidize, and unblocking solution on the quantitative yield of oligonucleotides during manufacturing of the test-system for Vibrio cholerae (ctxA+) DNA detection “GenChol”, using polymerase chain reaction.Materials and methods. The subject of the study is ctx2 and ctx3 primers, incorporated in the test-system “GenChol”. Utilized have been experimental formulations of solutions for unblocking, activator, and oxidizer and “standard” solutions, recommended by the manufacturer “BioSet” Ltd. Specific activity of the synthesized primers ctx2 and ctx3 has been evaluated on three different strains: V. cholerae 569B, M-1298, 158 and E. coli 12226 O-55. Bacterial suspension from the pathogen with final concentration of 1·103 – 1·101 m.c./ml has been produced. The DNA has been isolated applying nucleo-sorption in presence of guanidinium isothiocyanate.Results and conclusions. Demonstrated is the possibility of optimization of diagnostic preparation production via increment of oligonucleotide yield in the process of phosphoramide synthesis, due to application of 3% dichloroacetic acid in dichloromethane as unblocking solution and oxidizer – 0.1 M iodine in athetic acid and pyridine in the ratio of 1:9. Utilization of such reagents increases the yield of the end product (primers) by 6 and 95 %, respectively. Enhanced technology for oligonucleotide synthesis will provide for the reduction of costs, associated with expensive imported reagents and the raise in the numbers of gene-diagnostic preparations for the detection of particularly dangerous pathogens

Atomically thin boron nitride: a tunnelling barrier for graphene devices

We investigate the electronic properties of heterostructures based on ultrathin hexagonal boron nitride (h-BN) crystalline layers sandwiched between two layers of graphene as well as other conducting materials (graphite, gold). The tunnel conductance depends exponentially on the number of h-BN atomic layers, down to a monolayer thickness. Exponential behaviour of I-V characteristics for graphene/BN/graphene and graphite/BN/graphite devices is determined mainly by the changes in the density of states with bias voltage in the electrodes. Conductive atomic force microscopy scans across h-BN terraces of different thickness reveal a high level of uniformity in the tunnel current. Our results demonstrate that atomically thin h-BN acts as a defect-free dielectric with a high breakdown field; it offers great potential for applications in tunnel devices and in field-effect transistors with a high carrier density in the conducting channel.Comment: 7 pages, 5 figure

How close can one approach the Dirac point in graphene experimentally?

The above question is frequently asked by theorists who are interested in graphene as a model system, especially in context of relativistic quantum physics. We offer an experimental answer by describing electron transport in suspended devices with carrier mobilities of several 10^6 cm^2V^-1s^-1 and with the onset of Landau quantization occurring in fields below 5 mT. The observed charge inhomogeneity is as low as \approx10^8 cm^-2, allowing a neutral state with a few charge carriers per entire micron-scale device. Above liquid helium temperatures, the electronic properties of such devices are intrinsic, being governed by thermal excitations only. This yields that the Dirac point can be approached within 1 meV, a limit currently set by the remaining charge inhomogeneity. No sign of an insulating state is observed down to 1 K, which establishes the upper limit on a possible bandgap

THREATS TO INDUSTRIAL POLICY, TRADE AND KNOWLEDGE SHARING IN A GLOBAL EMERGENCY

The coronavirus epidemic 2019-nCoV in China has already led to a slowdown in the country’s economic growth and the fall of the yuan exchange rate on the stock exchanges. The Russian government has banned visa-free tourist trips between Russia and China and the issuance of work visas to Russia for Chinese citizens; Australia, New Zealand, Japan, Pakistan, and Italy have imposed similar bans. Great Britain, South Korea, Singapore and New Zealand have imposed quarantine for arrivals from China. Military aircrafts of Russia, India and Thailand take their citizens out of China. The US authorities have declared public health emergency and ban on the entry of all foreign citizens who have visited China over the past two weeks. This article gives forecast, how these measures of the governments will affect on global academic mobility and economic growth

MECHANISMS FOR ENSURING SUSTAINABLE DEVELOPMENT AND FOOD SECURITY OF A SOVEREIGN COUNTRY

The social and climatic factors that affect the global and regional food systems of states and regions have been highlighted in the article. The importance of ensuring food security and balanced nutrition of the population at a time of economic hardship to reduce the vulnerability of the economy and strengthen the political stability of the Russian Federation, to build capacity to withstand the crisis and rapid recovery from it has been noted. The problems of food security and tasks aimed at preventing internal and external threats, sustainable development of domestic production sufficient to ensure food independence and state sovereignty have been considered