Necklace-Cloverleaf Transition in Associating RNA-like Diblock Copolymers

We consider a ${\rm A}_m{\rm B}_n$ diblock copolymer, whose links are capable of forming local reversible bonds with each other. We assume that the resulting structure of the bonds is RNA--like, i.e. topologically isomorphic to a tree. We show that, depending on the relative strengths of A--A, A--B and B--B contacts, such a polymer can be in one of two different states. Namely, if a self--association is preferable (i.e., A--A and B--B bonds are comparatively stronger than A--B contacts) then the polymer forms a typical randomly branched cloverleaf structure. On the contrary, if alternating association is preferable (i.e. A--B bonds are stronger than A--A and B--B contacts) then the polymer tends to form a generally linear necklace structure (with, probably, some rear side branches and loops, which do not influence the overall characteristics of the chain). The transition between cloverleaf and necklace states is studied in details and it is shown that it is a 2nd order phase transition.Comment: 17 pages, 9 figure

NN potentials from inverse scattering in the J-matrix approach

An approximate inverse scattering method [7,8] has been used to construct separable potentials with the Laguerre form factors. As an application, we invert the phase shifts of proton-proton in the $^1S_0$ and $^3P_2-^3F_2$ channels and neutron-proton in the $^3S_1-^3D_1$ channel elastic scattering. In the latter case the deuteron wave function of a realistic $np$ potential was used as input.Comment: LaTex2e, 17 pages, 3 Postscript figures; corrected typo

Localization in simple multiparticle catalytic absorption model

We consider the phase transition in the system of n simultaneously developing random walks on the halfline x>=0. All walks are independent on each others in all points except the origin x=0, where the point well is located. The well depth depends on the number of particles simultaneously staying at x=0. We consider the limit n>>1 and show that if the depth growth faster than 3/2 n ln(n) with n, then all random walks become localized simultaneously at the origin. In conclusion we discuss the connection of that problem with the phase transition in the copolymer chain with quenched random sequence of monomers considered in the frameworks of replica approach.Comment: 17 pages in LaTeX, 5 PostScript figures; submitted to J.Phys.(A): Math. Ge

Radiation-induced hydrogen transfer in metals

The paper presents processes of hydrogen (deuterium) diffusion and release from hydrogen-saturated condensed matters in atomic, molecular and ionized states under the influence of the electron beam and X-ray radiation in the pre-threshold region. The dependence is described between the hydrogen isotope release intensity and the current density and the electron beam energy affecting sample, hydrogen concentration in the material volume and time of radiation exposure to the sample. The energy distribution of the emitted positive ions of hydrogen isotopes is investigated herein. Mechanisms of radiation-induced hydrogen transfer in condensed matters are suggested

Nucleon-nucleon interaction in the JJ-matrix inverse scattering approach and few-nucleon systems

The nucleon-nucleon interaction is constructed by means of the $J$-matrix version of inverse scattering theory. Ambiguities of the interaction are eliminated by postulating tridiagonal and quasi-tridiagonal forms of the potential matrix in the oscillator basis in uncoupled and coupled waves, respectively. The obtained interaction is very accurate in reproducing the $NN$ scattering data and deuteron properties. The interaction is used in the no-core shell model calculations of $^3$H and $^4$He nuclei. The resulting binding energies of $^3$H and $^4$He are very close to experimental values.Comment: Text is revised, new figures and references adde

Reassessment of disease severity routine laboratory tests in the COVID-19 infection

Introduction. Publications demonstrate some limitations of National Early Warning Score 2 (NEWS-2) accuracy in assessment on coronavirus infection severity.The purpose of this study was to determine the value of the patient’s age and routine laboratory parameters in the assessment of patient’s general condition in coronavirus pneumonia and their relation to NEWS-2 scale parameters.Materials and methods. 50 case reports of patients with COVID-19 infection observed in the Sechenov University in January–March 2021 were analyzed. 34 % of patients were males aged 31 to 89 years (average age 55 years) and 66 % — females aged 40 to 91 (mean age 63). The diagnosis of pneumonia was confirmed by computed tomography. NEWS-2 scale total score was assessed.Results. According to the physician’s subjective assessment the condition was significantly more often assessed as moderate and severe. There was only a weak correlation between the blood oxygen saturation and the total NEWS-2 score (r = 0.165, α = 0.1). We found a mild correlation (r = 0.341, α = 0.1) between the patient’s age and NEWS2 score. Among the most significantly interrelated parameters were age, neutrophil count, serum creatinine, CRP, fibrinogen level. Seven interrelated parameters (age, body temperature, blood oxygen saturation, the neutrophils count, creatinine, CRP, fibrinogen), for which a reliable relation with other tests has been shown, were assigned with its special index according to their contribution to the assessment of the overall condition severity. An aggregated score (criterion X) was proposed for assessment of disease severity according to equation. The proportions of mild, moderate, and severe cases according to criterion X were 12 %, 64 % and 24 %.Conclusion. The preliminary results obtained in the study emphasize the importance of routine laboratory tests in assessment of coronavirus infection severity. An evident discrepancy between NEWS-2 score and X criterion may be very important for practice

Random walks in the space of conformations of toy proteins

Monte Carlo dynamics of the lattice 48 monomers toy protein is interpreted as a random walk in an abstract (discrete) space of conformations. To test the geometry of this space, we examine the return probability $P(T)$, which is the probability to find the polymer in the native state after $T$ Monte Carlo steps, provided that it starts from the native state at the initial moment. Comparing computational data with the theoretical expressions for $P(T)$ for random walks in a variety of different spaces, we show that conformational spaces of polymer loops may have non-trivial dimensions and exhibit negative curvature characteristic of Lobachevskii (hyperbolic) geometry.Comment: 4 pages, 3 figure

Study of the graphene oxide nanoparticles effect on luminol-dependent chemiluminescence of human leukocytes

Graphene and its derivatives are increasingly used in biomedical research. Therefore, the mechanisms and consequences of the interaction of graphene nanoparticles with living objects are intensively studied. The immune system is involved in protecting the body and regulating its functions, so the question of the effect of graphene and its derivatives on immune cells is crucial. The specific response of monocytes, macrophages, and neutrophils to a stimulus is to increase the production of reactive oxygen species (ROS). Published data on graphene oxide (GO) and polyethylene glycol-modified graphene oxide (GO-PEG) effects on peripheral blood leukocytes are scarce and contradictory. It is due to variations in objects and conditions of study, along with the difference in particle concentrations. Thus, it was essential to evaluate the GO and GO-PEG effect on ROS production by human leukocytes. Our study aimed at the effect of particles of unmodified and PEG-modified graphene oxide (GO and GO-PEG) on the ROS production by peripheral blood leukocytes in not-stimulated and stimulated luminoldependent chemiluminescence (LCL) tests. ROS production was stimulated by opsonized zymosan (OZ). A hydrogen peroxide-luminol system was used for assessing the independent effect of GO nanoparticles on the quenching of ROS luminescence. Pristine GO (Ossila, Great Britain) nanoparticles were PEG-modified (GO-PEG). The average size of the GO flakes was 1-5 µm, the GO-PEG-flakes 569±14 nm, and the amount of PEG covering was ~ 20%. Nanoparticles were used at concentrations of 5; 2.5; 1.25 µg/ml. It has been established that GO-PEG nanoparticles in concentrations of 2.5 and 5 µg/ml suppressed ROS production in the spontaneous LCL test. At the same time, the GO effects showed a visible but a not significant tendency to inhibition of LCL. Similar results were obtained in the stimulated LCL test. However, when analyzing the process kinetics, both GO-PEG and GO decreased the ROS production, but mainly in the first minutes of the test. When analyzing the quenching effect of the LCL reaction in a cell-free system, there was no significant effect of GO and GO-PEG nanoparticles. Thus, the general vector of the obtained effects was associated with the suppression of ROS production. GO-PEG ROS-decreasing effects were more pronounced in comparison with unmodified GO. In general, we have confirmed the antioxidant effects of GO and GO-PEG using the LCL method. We can assume that in addition to the actual antioxidant effect of graphene nanoparticles, ROS production decreases due to the rapid GO uptake and blocking of several intracellular signals that induce an oxidative burst

Epidemiological features Delta together multiple infection in Saint-Petersburg

Studied the epidemiological features of the delta as a coinfection of hepatitis B in Saint-Petersburg for 14-year period (2002–2014). Clinical and laboratory data of 232 patients admitted to Botkin CIB them during this period. Revealed a 2-fold increase in performance of co-infection (Br + + IOP HIV) by 2014. In 49,6% of patients (group 1) were diagnosed less often chronic and acute forms of HBV in combination with delta infection. In 24,5% of cases (group 2) delta infection is associated with chronic hepatitis B and C. In the remaining 25,9% of the cases (B group) occurred multiple infection(HBV + HCV + HIV + IOP). Based on the clinical and epidemiological and laboratory data in 75,8% of patients defined delta superinfection, at 24,2% – co-infection. The marked increase in co-delta infection in recent years due to the accumulation of the potential epidemic of chronic hepatitis B in the population and the increase in the number of imported cases from 8,8% to 37,2% of migrants in the city. Cytolytic components, characterized by higher rates of ALT activity was most pronounced in the first group and the third group is minimal. However, the mean activity values for patients of the 3rd group were higher than in the first. ACAT groups had the same tendency as AlAt. Patients third group was a higher mortality, compared with other groups