Investigation of DNA denaturation in Peyrard-Bishop-Dauxois model by molecular dynamics method

The phase transition of $(PolyA/PolyT)_{100}$ duplex into the denaturated state is studied in the Peyrard-Bishop-Dauxois model by the method of direct molecular-dynamical modeling. The temperature dependencies of the total energy and heat capacity of the duplex are calculated. The approach applied can be used to calculate the statistical properties of the duplexes of any length and nucleotide composition.Comment: 6 pages, 4 figure

A mortal case of coronavirus disease in a pregnant diabetic woman. Clinical case

Pregnant women are very susceptible to coronavirus infection. Gestational diabetes mellitus is severe comorbidity and a serious risk factor for lethal outcomes. We report a mortal case of coronavirus disease (COVID-19) associated with bilateral pneumonia and systemic inflammatory response syndrome in a pregnant woman with gestational diabetes mellitus. Patient was admitted to the hospital at 31 weeks of gestation with COVID-19 bilateral pneumonia. Anti-inflammatory, antiviral, antibacterial and immunomodulatory treatment was started. She received per os favipiravir 200 mg, azithromycin 500 mg, enfluvir 75 mg, plaquenil 200 mg, and ceftriaxone 1 g intravenously, piperacillin 4.5 g intravenously, methylprednisolone 40 mg intramuscular, enoxaparin 0.6 subcutaneously. The doses of insulin were changed. But maternal status became worse in several hours. Oxygen saturation dropped to 80%. Patient was intubated and connected to the artificial lung ventilator. The cesarean was performed. The preterm born baby with early neonatal sepsis diseased the next day. The treatment could not counteract an inflammatory storm. Despite intensive resuscitation, the woman diseased. The fatal case of COVID-19 was associated with coexisted gestational diabetes mellitus and late admission to the hospital. The COVID-19 patients with gestational diabetes mellitus are at higher risk of severe pneumonia, systemic inflammatory response and carbohydrate metabolism decompensation. Oxidative stress caused by bilateral pneumonia initiated the chain of tissue injury-related reactions. The fat tissue is an additional source of free radicals and proinflammatory cytokines. Progression of the proinflammatory scenario enhanced multiple organ failure. We have found signs of acute pulmonary, hepatic, and renal insufficiency. The unresponsiveness to treatment contributed to systemic inflammatory response and maternal deterioration. Further investigations are necessary to improve outcomes in COVID-19 during pregnancy

Delayed neurological maturation is a cause for distress during fetal growth restriction

Theory of fetal programming contributes to a better understanding of the relationship of many human diseases with antenatal period pathology. Regulatory impact of nervous system is of great importance. Fetal growth restriction (FGR) is a convenient model for investigation of the abnormalities of fetal neurodevelopment. Fetal heart rate variability is a well-known approach for fetal autonomic function detection. The aim of the study was to detect several patterns of autonomic nervous regulation in FGR complicated by fetal distress or without fetal distress. Materials and methods. Totally 64 patients at 26–28 weeks of gestation were enrolled. 23 patients had normal fetal growth and were included in the Group I (control). 20 pregnant women with FGR without fetal distress were observed in Group II. 21 patients with FGR and fetal distress were included in Group III. Fetal heart rate variability and conventional cardiotocographic patterns were obtained from the RR-interval time series registered from the maternal abdominal wall via non-invasive fetal electrocardiography. Results. Suppression of the total level of heart rate variability with sympathetic overactivity was found in FGR. The maximal growth of sympathovagal balance was found in Group III. Fetal deterioration was associated with an increased quantity of decelerations, reduced level of accelerations, and decreased of short term variations and low term variations. But a decelerative pattern before 26 weeks of gestation was normal. Therefore fetal autonomic malfunction could be a result of persistent neurological immaturity in FGR. The approach based on the monitoring of fetal autonomic maturity in the diagnosing of its well-being should be tested in further studies. Conclusion. Fetal heart rate variability variables and beat-to-beat variations parameters could be the sensitive markers of neurological maturation and good predictors for fetal deterioration

Building Heat-insulating Materials Based on the Products of the Transesterification of Polyethylene Terephthalate and Dibutyltin Dilaurate

In this paper, we offered a technological basis for production of heat-insulating polyurethane materials based on the aromatic polyester - the product of transesterification of polyethylene terephthalate and corrective additive - dibutyltin dilaurate. Also, we presented the formulation and properties of the developed polyurethanes

Theoretical evaluation of rheological state of sand cement composite systems with polyoxyethylene additive using topological dynamics concept

© 2016 Trans Tech Publications, Switzerland.Presents the results of studies of contemporary materials in the field of rheological state. The topological mortar structure has been provided by theoretical evaluation of the rheological state of the cross-linked solutions and the experimental viscosity data of the sand cement mortar which has been modified by water-soluble additive – polyoxyethylene. The general model has been made for the structure of non-Newtonian liquideous systems including dilatant, pseudoplastic bodies with two main rheological active components in their structure – rigid and viscous phases. It is shown that in pseudoplastic systems, as the shear stress increases, the viscous phase grows because of the reduction of rigid phase content. In dilatant systems the converse situation has been observed. Furthermore, these phases are not clearly distinguishable, but to the contrary they are spatially interconnected in a complex way. The structure modeling has been made for non-Newtonian bodies using the Shklovskii-de Gennes model. The studies have found that the construction composite sand cement system is defined as the pseudoplastic body where cement and sand act as the rigid phase, water solution of polyoxyethylene – as the viscous phase. These findings can be used to prove the influence of polymer powder on the workability of dry mortar

Composites with improved absorption of noise and vibration

© 2017, Allerton Press, Inc. The development of composites based on thermosetting resins with improved vibration and noise absorption is considered. Mathematical and topological models are proposed to describe the influence of the composition on the vibration and noise absorption and elastic properties of the composites. The composition of filled epoxy, polyester, and polyurethane vibration-absorbing composites is optimized in terms of their loading, dynamic, and economic characteristics