We studied the annihilation kinetics for triplet excitations in isolated pairs of organic molecules and their delayed fluorescence decay using a new mathematical model for the process. According to this model, the intensity of delayed annihilation fluorescence (DAF) for isolated pairs is directly proportional to the number of pairs in which both molecules are found in the excited triplet state. We show that the decrease in such pairs and the decay of their delayed annihilation fluorescence occur according to an exponential law in the absence of random scatter in the deactivation rate constants for the triplet excitations. The results of an experimental study of the DAF decay kinetics for 1,12-benzoperylene in n-hexane at 77 K, where triplet-triplet annihilation occurs in isolated pairs, confirm the validity of the theoretical conclusions.Introduction. Triplet-triplet annihilation (TTA) and delayed annihilation fluorescence (DAF) due to it are often used as a method (see, for example, [1]) for studying photoprocesses with participation of triplet states of organic molecules. In order to improve the reliability of this method, we need to know the characteristic features of the TTA process, including its kinetics. The TTA kinetics in condensed media are evaluated from the nature of DAF decay [1, 2]. However, DAF decay cannot always be described in all its stages using models available in the literature [2,3]. In [4,5] it is shown that researchers encounter such a problem in cases when there is no convergence process (no migration of the excitation, no diffusion of the excited molecules) between the event of the appearance of excitation in the molecule and the event of annihilation. In disordered media (doped glasses, polymer matrices, etc.), the triplet excitations converge for sufficiently high concentration of the impurity centers as a result of their migration relative to the triplet levels of the acceptor. In this case, DAF is the result of migration-controlled TTA, and all triplet excitations can participate in it.In polycrystalline n-paraffin solutions (for molecules responsible for quasi-line DAF spectra [6]) and for sufficiently low concentrations of the impurity centers in glassy solutions, TTA occurs in non-interacting pairs (isolated pairs). Here there is no excitation convergence process, so if one of the triplet-excited molecular makes a transition to the ground state after the excitation stops as a result of unimolecular deactivation, the second molecule can no longer participate in TTA.Despite the differences indicated above, it is assumed that in both cases the following relation is valid for the DAF intensity:

Данная интернет-версия статьи была скачана с сайта http://www.gynecology.su.Не предназначено для использования в коммерческих целях.Информацию о репринтах можно получить в редакции. Тел.:

Aim: to objectively assess potential for early generalized postpartum infection diagnostics prior to the onset of irreversible organ changes based on a retrospective analysis.Materials and Methods. Сlinical and laboratory forensic medical data were examined by analysing 29 cases of severe maternal outcomes coupled to sepsis: including 17 «near miss» and 12 deceased patients (maternal mortality). The control group consisted of 30 patients who had chorioamnionitis in labor and successfully completed pregnancy. Statistical data analysis was carried out by using nonparametric statistics by creating conjugacy tables and assessing a relationship between parameters with Pearson χ2 distribution.Results. There were found significant differences in rate of some symptoms in both groups. Patients with severe maternal outcomes vs. control group were significantly more likely to develop hyperthermia ≥ 38.0 °C or hypothermia ≤ 36.0 °C, hectic fever, leukocytosis ≥ 12×109/L or leukopenia ≤ 4×109/L before the end of pregnancy; after pregnancy, persistent subfebrility, febrility or hypothermia, hectic fever, multiple-organ failure syndrome (PON), as well as uterine subinvolution and abnormal discharge from the genital tract were observed.Conclusion. Early identification of recognized symptoms of systemic inflammatory response syndrome and PON allows to properly assess severity of patient condition, taking into account the risk of generalized infection, contributes to making correct diagnosis and timely implementation of adequate organizational and therapeutic measures.

No abstract

BACKGROUND: The presence of COVID-19 caused by SARS-CoV-2 during pregnancy increases the incidence of adverse perinatal outcomes, which are manifested in more frequent spontaneous miscarriages, premature births, antenatal fetal deaths, and fetal growth retardation, as well as in the development of intraamniotic infection and respiratory distress syndrome of the newborn. The most likely cause of premature birth can be considered severe respiratory failure of the mother with hypoxemia, which leads to circulatory disorders in the hemodynamic system of the mother-placenta-fetus. Currently, there is no single expert opinion on pregnancy prolongation tactics, as well as the timing and methods of delivery in patients with COVID-19, which is decided individually by an interdisciplinary consultation of the experts, taking into account the severity of the patients condition, gestational age and fetal condition. AIM: The aim of this study was to analyze perinatal outcomes of pregnancy and childbirth in the presence of moderate and severe COVID-19. MATERIALS AND METHODS: We carried out a retrospective analysis of perinatal outcomes in patients with the novel coronavirus infection in a specialized level III infectious hospital in St. Petersburg, Russia in 20202021 (from the first to the fourth wave of COVID-19) based on the birth histories of 50 patients with moderate (n = 31) and severe (n = 19) forms of the disease. RESULTS: Most of the patients suffered from chronic somatic diseases, with the course of pregnancy and childbirth complicated by premature rupture of amniotic fluid and progressive fetal hypoxia (fetal distress). In severe COVID-19, preterm labor prevailed and the proportion of operative abdominal delivery more than doubled that of vaginal delivery. The course of the postpartum period was determined by the COVID-19 positive dynamics. The majority of patients in the study groups showed significant changes in laboratory parameters such as anemia, an increase in the level of neutrophilic leukocytes with a subsequent decrease in their count, lymphopenia followed by lymphocytosis, and an increase in the levels of C-reactive protein and the activities of lactate dehydrogenase, alanine aminotransferase and aspartate aminotransferase. The study of the relationship between the most characteristic laboratory parameters in the disease dynamics showed the presence of statistically significant correlations between inflammation markers and metabolic markers, which allowed for assessing the severity of the patients condition. Antenatal diagnosis of the fetal functional status based on cardiotocography, ultrasound and Doppler sonography data revealed a predominantly compensated fetal condition in the study groups. The condition of newborns in all patients with moderate COVID-19 and in most of patients with the severe form of the disease was satisfactory. In severe COVID-19, the birth of children with moderate asphyxia was due to prematurity and antenatal hypoxia resulted from decompensation of chronic placental insufficiency. The histopathological patterns of the afterbirth in the study groups were represented by inflammatory changes and chronic placental insufficiency. CONCLUSIONS: The data obtained suggest that the basis for favorable perinatal outcomes is an adequate assessment of the condition of the pregnant woman and the fetus with timely delivery before the onset of irreversible organ damage.