Precision Quantum Hall Resistance Measurement on Epitaxial Graphene Device in Low Magnetic Field

Precision quantum Hall resistance (QHR) measurements were performed on large-area epitaxial graphene device at low magnetic fields (B = 2 T - 8 T) at temperature T = 1.5 K. Hall resistance was measured using Cryogenic Current Comparator resistance bridge with high biasing current Isd = 40 micro ampere. The results showed that at B = 8 T the relative deviation of Hall resistance from the expected quantized value h/2e2 is within experimental uncertainty of 3.5 parts in 108 and remained below 0.35 parts per million (ppm) down to B = 3 T

Role of Toll-like receptors in development of postpartum endometritis

The aim of the study was to establish the association between expression of TLR1 (ligands - triacyl lipopeptides), TLR2 (ligands - lipopeptides, lipoteichoic acid, zymosan), and TLR 5 (ligand - flagellin) of cervical epithelial cells in vivo and development of postpartum endometritis in women with high infection riskyesBelgorod State Universit

Spin disorder scattering in a ferromagnetic insulator-on-graphene structure

We theoretically study the transport properties of a single graphene layer between two insulating materials, i.e., a ferromagnetic EuO thin film and a nonmagnetic SiC substrate. An exchange interaction between the charge carrier spins in graphene and the localized magnetic moments in the ferromagnetic insulator is assumed. This proximity effect and the large spin fluctuations at temperatures close to the ferromagnetic transition temperature TC lead to spin disorder scattering, which is calculated using a Green's function technique. Numerical results indicate that at temperatures close to TC the contribution of the spin disorder scattering to the total electron mobility is clearly observable even in the case of a weak exchange interaction and a low background mobility of the graphene layer. This enables the experimental determination of the exchange interaction parameter using the present model and a simple resistivity measurement.Peer reviewe

Towards a Graphene-Based Quantum Impedance Standard

Precision measurements of the quantum Hall resistance with alternating current (ac) in the kHz range were performed on epitaxial graphene in order to assess its suitability as a quantum standard of impedance. The quantum Hall plateaus measured with alternating current were found to be flat within one part in 10^7. This is much better than for plain GaAs quantum Hall devices and shows that the magnetic-flux-dependent capacitive ac losses of the graphene device are less critical. The observed frequency dependence of about -8x10^-8/kHz is comparable in absolute value to the positive frequency dependence of plain GaAs devices, but the negative sign is attributed to stray capacitances which we believe can be minimized by a careful design of the graphene device. Further improvements thus may lead to a simpler and more user-friendly quantum standard for both resistance and impedance

Some features of the bioelectric activity of the muscles with prolonged hypokinesia

The effects of prolonged hypokinesia, brought on by confinement to bed and the attendant lack of motor activity, on the bioelectric activity of muscles are studied. Electromyographic measurements of amplitude and frequency indicators of muscular bioelectric activity were analyzed

Expression of TLR1-10 and caspase-3 alfa at women with early miscarriages

Toll-like receptors (TLR) are the first signal receptors of innate immunity, recognizing bacteria and viruses and promoting development of inflammation through the activation of proinflammatory cytokines secretion (1). In animal models it was shown, that TLRs play role in pathogenesis of miscarriages (2, 3) and can influence to trophoblast apoptosis. The aim of research was to investigate study specialty of mRNA expression of TLR1-10 and caspase-3a in endometrium at patients with early miscarriagesyesBelgorod State Universit

Hydrolysate of ovalbumin: production and evaluation of the functional properties of peptides

Chicken eggs proteins and their derivatives, like protein hydrolysates, peptides and amino acids, possess high nutritional value and provide a wide range of biological activity. They serve as sources for development of functional ingredients that draw the attention of specialists in the food production and biomedical industries, as well as the livestock feed industry. Enzymatic hydrolysis of proteins is a popular process for obtaining bioactive peptides with multifunctional properties. The purpose of this study is to obtain a hydrolysate of ovalbumin with a high degree of hydrolysis and to determine its functional and technological parameters. The research presents a two-stage scheme of ovalbumin hydrolysis with the help of pepsin and trypsin which provide high degree of hydrolysis (82–83%). The fractional composition of the hydrolysate is determined. The fractional composition is represented by three main fractions (high, medium and low molecular weight). The summarized antioxidant activity (SAA) of the hydrolysate is considered within the dynamics of the hydrolysis process. The highest SAA value was noted after 2 hours, and it amounted to 170.23 mg/l; at the end of hydrolysis the SAA value was equal to 114.31 mg/l. When analyzing the SAA, it was found that the main contribution to the summarized antioxidant activity of the ovalbumin hydrolysate is made by peptides of the medium molecular fraction. The microfiltration process, used in the research, made it possible to separate high-molecular compounds, which led to an increase in the SAA of the hydrolysate to 189.9 mg/l. The main functional and technological parameters of the hydrolysate are determined in this research. The comprehensive study of the biological activity and functional characteristics of egg protein hydrolysates and their peptides provides a theoretical basis for expanding the range of functional ingredients obtained from food proteins and for replenishing the range of functional foods.Chicken eggs proteins and their derivatives, like protein hydrolysates, peptides and amino acids, possess high nutritional value and provide a wide range of biological activity. They serve as sources for development of functional ingredients that draw the attention of specialists in the food production and biomedical industries, as well as the livestock feed industry. Enzymatic hydrolysis of proteins is a popular process for obtaining bioactive peptides with multifunctional properties. The purpose of this study is to obtain a hydrolysate of ovalbumin with a high degree of hydrolysis and to determine its functional and technological parameters. The research presents a two-stage scheme of ovalbumin hydrolysis with the help of pepsin and trypsin which provide high degree of hydrolysis (82–83%). The fractional composition of the hydrolysate is determined. The fractional composition is represented by three main fractions (high, medium and low molecular weight). The summarized antioxidant activity (SAA) of the hydrolysate is considered within the dynamics of the hydrolysis process. The highest SAA value was noted after 2 hours, and it amounted to 170.23 mg/l; at the end of hydrolysis the SAA value was equal to 114.31 mg/l. When analyzing the SAA, it was found that the main contribution to the summarized antioxidant activity of the ovalbumin hydrolysate is made by peptides of the medium molecular fraction. The microfiltration process, used in the research, made it possible to separate high-molecular compounds, which led to an increase in the SAA of the hydrolysate to 189.9 mg/l. The main functional and technological parameters of the hydrolysate are determined in this research. The comprehensive study of the biological activity and functional characteristics of egg protein hydrolysates and their peptides provides a theoretical basis for expanding the range of functional ingredients obtained from food proteins and for replenishing the range of functional foods

Magnetically operated nanorelay based on two single-walled carbon nanotubes filled with endofullerenes Fe@C20

Structural and energy characteristics of the smallest magnetic endofullerene Fe@C20 have been calculated using the density functional theory approach. The ground state of Fe@C20 is found to be a septet state, and the magnetic moment of Fe@C20 is estimated to be 8 Bohr magnetons. Characteristics of an (8,8) carbon nanotube with a single Fe@C20 inside are studied in the framework of the semiempirical approach. The scheme of a magnetic nanorelay based on cantilevered nanotubes filled with magnetic endofullerenes is elaborated. The proposed nanorelay is turned on as a result of bending of nanotubes by a magnetic force. Operational characteristics of such a nanorelay based on (8,8) and (21,21) nanotubes fully filled with Fe@C20 are estimated and compared to the ones of a nanorelay made of a (21,21) nanotube fully filled with experimentally observed (Ho3N)@C80 with the magnetic moment of 21 Bohr magnetons. Room temperature operation of (21,21) nanotube based nanorelays is shown.Comment: 18 pages, 9 figure

Impact monitoring of mining enterprises of Kursk magnetic anomaly on hydro ecological river situation of the Belgorod region

The results of contrastive analysis of hydrochemical state of surface water bodies exposed to the impact of mining enterprises, by way of example of small rivers of the Belgorod region, according to the results of exploration carried out in the years 2009-201