Применение метода диэлектрической спектроскопии для исследования свойств сыворотки крови мышей со злокачественным асцитом

The article presents the results of a study by the method of dielectric spectroscopy of high-frequency relaxation processes in the blood serum of intact mice and mice vaccinated with an oncological disease - Ehrlich's ascites carcinoma. Using the formalism of the electrical module, the relaxation parameters were calculated for the serum samples of the two studied systems.

How much entropy is contained in NMR relaxation parameters?

Solution-state NMR relaxation experiments are the cornerstone to study internalprotein dynamics at atomic resolution on time scales that are faster than the overallrotational tumbling time,τR. Since the motions described by NMR relaxation pa-rameters are connected to thermodynamic quantities like conformational entropies, thequestion arises how much of the total entropy is contained within this tumbling time.Using all-atom molecular dynamics (MD) simulations of T4 lysozyme, we found thatentropy build-up is rather fast for the backbone, such that the majority of the entropyis indeed contained in the short-time dynamics. In contrast, the contribution of slowdynamics of side chains on time scales beyondτRon the side chain conformationalentropy is significant and should be taken into account for the extraction of accuratethermodynamic properties.

The use of the formalism of the complex electrical module in the monitoring of oncological diseases

The article discusses the use of the formalism of a complex electrical module to determine the relaxation parameters α, β, τ of blood serum. Approximating formulas for the real and imaginary components of the electrical modulus, obtained from the Havrilyak-Negami equation, are given. The assumption is made that for healthy organisms the parameters α, β, τ are constant (or change insignificantly), and for cancer patients they change, and the more the disease develops, the more these parameters change. It is also assumed that the activation energies Ea of macromolecules in the composition of blood serum are different for healthy and diseased organisms. Thus, the study of the dynamics of changes in the parameters α, β, τ, Ea can be used in the monitoring of oncological diseases.

AC Susceptibility Studies of Magnetic Relaxation in Mn12-Stearate SMMs on the Spherical Silica Surface

The study of magnetic relaxations in Mn12-stearate single-molecule magnets deposited on the surface of spherical silica nanoparticles was performed. For such a purpose, the investigation of AC magnetic susceptibility dependence on the frequency and temperature was performed. Based on the Argand plots obtained for different temperatures and temperature dependencies of susceptibility, obtained for different frequencies of AC field, the corresponding relaxation times were derived. Fitting to the Arrhenius law revealed the values of an effective energy barrier and a mean relaxation time, which were consistent for both measuring techniques (Ueff/kB∼ 50 K and τ0∼ 10−7 s) and similar to the corresponding values for the analogous bulk compounds. Additionally, the obtained relaxation parameters for the Mn12-stearate molecules on the spherical silica surface were compared with corresponding values for the Mn12-based single-molecule magnets deposited upon other types of nanostructured silica surface.

How much entropy is contained in NMR relaxation parameters?

Solution-state NMR relaxation experiments are the cornerstone to study internalprotein dynamics at atomic resolution on time scales that are faster than the overallrotational tumbling time,τR. Since the motions described by NMR relaxation pa-rameters are connected to thermodynamic quantities like conformational entropies, thequestion arises how much of the total entropy is contained within this tumbling time.Using all-atom molecular dynamics (MD) simulations of T4 lysozyme, we found thatentropy build-up is rather fast for the backbone, such that the majority of the entropyis indeed contained in the short-time dynamics. In contrast, the contribution of slowdynamics of side chains on time scales beyondτRon the side chain conformationalentropy is significant and should be taken into account for the extraction of accuratethermodynamic properties.

Dual-phase-lag one-dimensional thermo-porous-elasticity with microtemperatures

This paper is devoted to studying the linear system of partial differential equations modelling a one-dimensional thermo-porous-elastic problem with microtemperatures in the context of the dual-phase-lag heat conduction. Existence, uniqueness, and exponential decay of solutions are proved. Polynomial stability is also obtained in the case that the relaxation parameters satisfy a certain equality. Our arguments are based on the theory of semigroups of linear operators.

Longitudinal and Transverse Relaxivity Analysis of Native Ferritin and Magnetoferritin at 7 T MRI

Magnetite mineralization in human tissue is associated with various pathological processes, especially neurodegenerative disorders. Ferritin’s mineral core is believed to be a precursor of magnetite mineralization. Magnetoferritin (MF) was prepared with different iron loading factors (LFs) as a model system for pathological ferritin to analyze its MRI relaxivity properties compared to those of native ferritin (NF). The results revealed that MF differs statistically significantly from NF, with the same LF, for all studied relaxation parameters at 7 T: r1, r2, r2*, r2/r1, r2*/r1. Distinguishability of MF from NF may be useful in non-invasive MRI diagnosis of pathological processes associated with iron accumulation and magnetite mineralization (e.g., neurodegenerative disorders, cancer, and diseases of the heart, lung and liver). In addition, it was found that MF samples possess very strong correlation and MF’s relaxivity is linearly dependent on the LF, and the transverse and longitudinal ratios r2/r1 and r2*/r1 possess complementary information. This is useful in eliminating false-positive hypointensive artefacts and diagnosis of the different stages of pathology. These findings could contribute to the exploitation of MRI techniques in the non-invasive diagnosis of iron-related pathological processes in human tissue.

Thermal aspects of Oldroyd-B nanofluid over accelerated surface with variable thermal conductivity and modified diffusion theories

The growing interest in emerging nanotechnologies has led the scientists towards to investigate the interaction of nanoparticles with fluids. Current continuation endeavors the rheological analysis for the Oldroyd-B nanomaterial across periodically accelerated and heated surface. The interesting features of thermophoresis and Brownian motions are presented by following famous Buongiorno nanofluid model. Further, Cattaneo–Christov heat and mass flux expressions are exploited to determine the characteristics of thermal and mass diffusions. As a novelty, the variable thermal conductivity and heat absorption/generation consequences are also utilizing the energy equation. The flow model has been developed by using concerning boundary layer equations which are converted into dimensionless forms by using appropriate variables. The analytical solution of such transmuted equations is computed by using homotopy analytic method. Various physical parameters of interest are scrutinized through various graphs. The observations from analysis convey a declining change in nanofluid concentration and temperature with variation of thermal and solutal relaxation parameters, respectively. Moreover, thermophoresis parameter causes an enhancement of concentration profile while a retarded concentration profile results with increment of Schmidt number. The obtained theoretical results reflect significant applications in cooling and heating systems, thermal sciences, manufacturing processes, extrusion systems, enhancement of transport of energy and heat resources.