Ecological and biological features of Triglochin maritima L. in the biotopes of the littoral zone with different degree of flooding on the coast of the White Sea

The study of Triglochin maritima L. was carried out on the Pomor (western) coast of the White Sea, in the Republic of Karelia (64°22'81"N, 35°93'14"E). Morphological analysis of aboveground and underground parts of the clones was performed on virginal plants. Anatomical analysis of leaf sheaths of the current year shoots, rhizomes and adventitious roots was carried out. The viability of pollen was assessed by determining the relative share of normally developed and malformed pollen grains. The content of heavy metals was determined in the soil, sea water and plant samples. The study was carried out on a model transect in the littoral zone on three test plots representing the lower littoral; the middle and the upper littoral zones. Adaptation to wave and storm impact was manifested in a well-developed system of underground organs. In the lower littoral, underground part surpasses the aboveground vegetative organs in terms of the mass and the formation of mechanical tissues. This allows the plants to anchor stronger in the substrate. Pollen analysis confirmed the adaptability of T. maritima plants to the conditions of the lower littoral by a high percentage of normal and, consequently, fertile pollen, which ensures sexual reproduction of the species. T. maritima can be considered as a Fe hyperaccumulator as the plant accumulates very high levels of Fe (22–34 g kg-1), especially in the lower and middle littoral zones, both in underground and aboveground organs. The ability of T. maritima plants to actively deposit metals was revealed on the basis of the coefficient of biological absorption of metals and makes it possible to suggest potential possibility of using the species in phytoremediation technologies on coastal territories

QED cascades induced by circularly polarized laser fields

The results of Monte-Carlo simulations of electron-positron-photon cascades initiated by slow electrons in circularly polarized fields of ultra-high strength are presented and discussed. Our results confirm previous qualitative estimations [A.M. Fedotov, et al., PRL 105, 080402 (2010)] of the formation of cascades. This sort of cascades has revealed the new property of the restoration of energy and dynamical quantum parameter due to the acceleration of electrons and positrons by the field and may become a dominating feature of laser-matter interactions at ultra-high intensities. Our approach incorporates radiation friction acting on individual electrons and positrons.Comment: 13 pages, 10 figure

Low-Molecular Antioxidants Help Rare Orchids to Survive in Serpentine Dumps

В статье представлены результаты исследования морфофизиологических и биохимических характеристик орхидеи Epipactis atrorubens, произрастающей в естественном лесном фитоценозе и техногенно нарушенных местообитаниях. Изучены параметры листовой пластинки, водный режим листьев, уровень перекисного окисления липидов, а также содержание фотосинтетических пигментов и низкомолекулярных антиоксидантов в листьях растений. Результаты исследования показали, что адаптивные структурные перестройки листа и активация системы антиоксидантной защиты определяют не только способность редкого вида орхидей выживать в неблагоприятных условиях, но и успешно адаптироваться к ним.The article presents the results of a study of morphophysiological and biochemical characteristics of the orchid Epipactis atrorubens, growing in natural forest community and technogenic habitats. Leaf mesostructure, water regime and biochemical features (level of lipid peroxidation, content of photosynthetic pigments and low molecular weight antioxidants) of plants have been studied. The present study showed that the adaptive leaf structural rearrangements and activation of antioxidant defense system determine not only the ability of a rare orchids to survive in negative conditions, but also to successfully adapt to them

The heating rate influence on the elastic modulus temperature dependence of a corrosion-resistant nickel alloy

The temperature dependence of the elastic modulus of nickel-chromium-molybdenum alloy C4 was investigated by the method of dynamic mechanical analysis. At all heating rates, an abnormal increase in the elastic modulus is observed upon heating in the temperature range of 200-300 °C. It is shown that an increase in the heating rate shifts the beginning of the observed effect to the region of higher temperatures. The temperature anomaly in the elastic modulus of the C4 alloy is explained from the standpoint of the formation of a short-range order in a solid solution. The thermodynamically equilibrium temperature of the "disorder - short-range order" transition in C4 alloy is determined to be 205 °C. © Published under licence by IOP Publishing Ltd

ЭФФЕКТИВНОСТЬ ЛЕЧЕНИЯ БОЛЬНЫХ ВПЕРВЫЕ ВЫЯВЛЕННЫМ ТУБЕРКУЛЕЗОМ В ЗАВИСИМОСТИ ОТ ВИЧ-СТАТУСА

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Properties of electrons scattered on a strong plane electromagnetic wave with a linear polarization: classical treatment

The relations among the components of the exit momenta of ultrarelativistic electrons scattered on a strong electromagnetic wave of a low (optical) frequency and linear polarization are established using the exact solutions to the equations of motion with radiation reaction included (the Landau-Lifshitz equation). It is found that the momentum components of the electrons traversed the electromagnetic wave depend weakly on the initial values of the momenta. These electrons are mostly scattered at the small angles to the direction of propagation of the electromagnetic wave. The maximum Lorentz factor of the electrons crossed the electromagnetic wave is proportional to the work done by the electromagnetic field and is independent of the initial momenta. The momentum component parallel to the electric field strength vector of the electromagnetic wave is determined only by the diameter of the laser beam measured in the units of the classical electron radius. As for the reflected electrons, they for the most part lose the energy, but remain relativistic. There is a reflection law for these electrons that relates the incident and the reflection angles and is independent of any parameters.Comment: 12 pp, 3 fig

POLYFLUOROALKYL-2-(HET)ARYLHYDRAZONO-1,3-DICARBONYL COMPOUNDS IN INTRAMOLECULAR CYCLIZATION REACTIONS

This work was financially supported by the Program UB RAS (Grant number 18-3-3-13)

Fulminant invasive group A streptococcal infection in children

Group A streptococcal infections dominate among invasive streptococcal infections, with the major causative agent, Streptococcus pyogenes, being quite stable in the environment and bearing a large number of chromosome encoded pathogenicity factors or transmitted by horizontal transfer through bacteriophages. Different genetic variants of S. pyogenes can have a different set of pathogenicity factors able to change during pathogen evolution and determine virulence level for specific isolate. With a short incubation period, the disease can proceed with developing invasive infection and toxic shock syndrome with unfavorable outcome within 7 days from disease onset. The purpose of this article is to increase the doctors’ alertness to early recognition and diagnosis, which directly affects adequate treatment in a timely manner and disease outcome. The data on streptococcal morbidity in Russia and worldwide, review of laboratory diagnostic methods and pathogen genetic typing are presented. The maximum number of cases of streptococcal septicemia in Russia was registered in 2022, which accounted for 69% of all cases during the 2014–2022 observation period. The article also describes two clinical cases of fulminant invasive group A streptococcal infection in children with symptoms of acute respiratory viral infections at the onset of the disease. The results of various laboratory diagnostics methods verifying the diagnosis are presented. The genetic characterization of microbial isolates was performed by deep DNA sequencing. In the biological material from patients (including autopsy in one case), S. pyogenes sequence type ST-28, serotypes emm-1.25 and emm-1.0 were identified. The increasing importance of invasive streptococcal infection for health care in Russia and other countries may be associated with a possible change in dominating S. pyogenes genetic variants. In this regard, the study on circulating S. pyogenes genotypes on an ongoing basis as part of surveillance of streptococcal infection and development of vaccine for specific prevention are required