Zooplankton and Dead Zooplankton in Kharbeyskie Lakes of Bolshezemelskaya Tundra (Period From 2009 to 2012)

В июле–августе 2009, 2010, 2012 гг. исследован состав и структура зоопланктона в системе Харбейских озер Большеземельской тундры. Обнаружено 87 видов и форм, из которых более половины коловратки (Rotifera). Планктонная фауна обследованных озер обычна для южных тундр и представлена азональными таксонами. Зоопланктон оз. Большой Харбей и придаточных озер различался по составу и количественным показателям, которые соответствовали различным уровням трофности экосистем. Межгодовая динамика планктонных сообществ в озерах была связана с динамикой погодных условий. Доминантный комплекс зоопланктона по численности в оз. Большой Харбей состоял из четырех, по биомассе – из девяти видов, был представлен эвпланктонными видами как коловраток, так и ракообразных (Cladocera, Copepoda) и слабо изменялся по годам. В небольших придаточных озерах число доминирующих в планктоне видов было меньшим по сравнению с оз. Большой Харбей, в глубоководных – доминантный комплекс был сходен с таковым в Большом Харбее. Не было выявлено достоверных различий в количестве зоопланктона в литорали и профундали основного озера системы. Пространственное распределение видов соответствовало морфологическим особенностям водоемов. В 2012 г. в основном и придаточных Харбейских озерах наблюдалась депрессия планктонных Copepoda, проявлявшаяся в высокой доле мертвых особей этих ракообразных в численности рачкового планктона. Наблюдали поражение микропаразитами (вероятно, грибковое) доминирующего вида – Heterocope appendiculata (Copepoda)Zooplankton composition and structure in Kharbeyskie Lakes system of Bolshezemelskaya tundra were investigated in July, August of 2009, 2010 and 2012. In total, 87 species and forms were found and more than half of them belonged to rotifers (Rotifera). Plankton fauna of the studied lakes was typical for southern tundra and presented by azonal taxa. Composition and abundance of zooplankton of Bolshoy Kharbey Lake and adjacent lakes were different and correspond to trophic conditions in ecosystems. Inter-annual dynamics of plankton communities in the lakes was determined by weather conditions. In Bolshoy Kharbey Lake four euplanktonic species of rotifers and crustaceans (Cladocera and Copepoda) dominated in terms of abundance and nine species dominated in terms of biomass. Inter-annual changes in dominant species composition were insignificant. In Bolshoy Kharbey Lake the number of dominant species were more than in the adjacent lakes. Differences in the abundance of zooplankton between littoral and prophundal zones of the main lake were not significant. Spatial distribution of species was determined by the morphology of the lakes. Depression of plankton copepods in the main and adjacent Kharbeyskie Lakes was observed in 2012 and proportion of dead individuals in crustacean communities was high. Probably it was related with mass infection of dominant species Heterocope appendiculata (Copepoda) by microparasite

Fluctuating nonlinear spring theory:Strength, deformability, and toughness of biological nanoparticles from theoretical reconstruction of force-deformation spectra

We developed the Fluctuating Nonlinear Spring (FNS) model to describe the dynamics of mechanical deformation of biological particles, such as virus capsids. The theory interprets the force-deformation spectra in terms of the “Hertzian stiffness” (non-linear regime of a particle's small-amplitude deformations), elastic constant (large-amplitude elastic deformations), and force range in which the particle's fracture occurs. The FNS theory enables one to quantify the particles’ elasticity (Young's moduli for Hertzian and bending deformations), and the limits of their strength (critical forces, fracture toughness) and deformability (critical deformations) as well as the probability distributions of these properties, and to calculate the free energy changes for the particle's Hertzian, elastic, and plastic deformations, and eventual fracture. We applied the FNS theory to describe the protein capsids of bacteriophage P22, Human Adenovirus, and Herpes Simplex virus characterized by deformations before fracture that did not exceed 10–19% of their size. These nanoshells are soft (~1–10-GPa elastic modulus), with low ~50–480-kPa toughness – a regime of material behavior that is not well understood, and with the strength increasing while toughness decreases with their size. The particles’ fracture is stochastic, with the average values of critical forces, critical deformations, and fracture toughness comparable with their standard deviations. The FNS theory predicts 0.7-MJ/mol free energy for P22 capsid maturation, and it could be extended to describe uniaxial deformation of cylindrical microtubules and ellipsoidal cellular organelles

First circumpolar assessment of Arctic freshwater phytoplankton and zooplankton diversity : Spatial patterns and environmental factors

Arctic freshwaters are facing multiple environmental pressures, including rapid climate change and increasing land-use activities. Freshwater plankton assemblages are expected to reflect the effects of these stressors through shifts in species distributions and changes to biodiversity. These changes may occur rapidly due to the short generation times and high dispersal capabilities of both phyto- and zooplankton. Spatial patterns and contemporary trends in plankton diversity throughout the circumpolar region were assessed using data from more than 300 lakes in the U.S.A. (Alaska), Canada, Greenland, Iceland, the Faroe Islands, Norway, Sweden, Finland, and Russia. The main objectives of this study were: (1) to assess spatial patterns of plankton diversity focusing on pelagic communities; (2) to assess dominant component of beta diversity (turnover or nestedness); (3) to identify which environmental factors best explain diversity; and (4) to provide recommendations for future monitoring and assessment of freshwater plankton communities across the Arctic region. Phytoplankton and crustacean zooplankton diversity varied substantially across the Arctic and was positively related to summer air temperature. However, for zooplankton, the positive correlation between summer temperature and species numbers decreased with increasing latitude. Taxonomic richness was lower in the high Arctic compared to the sub- and low Arctic for zooplankton but this pattern was less clear for phytoplankton. Fennoscandia and inland regions of Russia represented hotspots for, respectively, phytoplankton and zooplankton diversity, whereas isolated regions had lower taxonomic richness. Ecoregions with high alpha diversity generally also had high beta diversity, and turnover was the most important component of beta diversity in all ecoregions. For both phytoplankton and zooplankton, climatic variables were the most important environmental factors influencing diversity patterns, consistent with previous studies that examined shorter temperature gradients. However, barriers to dispersal may have also played a role in limiting diversity on islands. A better understanding of how diversity patterns are determined by colonisation history, environmental variables, and biotic interactions requires more monitoring data with locations dispersed evenly across the circumpolar Arctic. Furthermore, the importance of turnover in regional diversity patterns indicates that more extensive sampling is required to fully characterise the species pool of Arctic lakes.Peer reviewe

Effectiveness of empirical <i>Helicobacter pylori</i> eradication therapy with furazolidone in Russia: results from the European Registry on <i>Helicobacter pylori</i> Management (Hp-EuReg)

Background. First-line therapy does not always provide a high level of Helicobacter pylori eradication due to the increase of H. pylori resistance to antibiotics; therefore, it remains necessary to identify the most effective rescue treatments. The purpose of this study was to evaluate the efficacy and safety of empirical H. pylori furazolidone-containing regimens. Materials and methods. Adult H. pylori infected patients empirically treated with furazolidone-containing eradication regimens were registered in an international, prospective, multicenter non-intervention European registry on H. pylori management (Hp-EuReg). Data were collected at AEG-REDCap e-CRF from 2013 to 2021 and the quality was reviewed. Modified intention-to-treat (mITT) effectiveness analyses were performed. Results. Overall 106 patients received empirical furazolidone-containing therapy in Russia. Furazolidone was prescribed in a sequential scheme along with amoxicillin, clarithromycin and a proton pump inhibitor in 68 (64%) cases, triple regimens were prescribed in 28 (26%) patients and quadruple regimens in 10 (9.4%). Treatment duration of 7 days was assigned to 2 (1.9%) patients, 10-day eradication therapy in case of 80 (75%) and 14 days in 24 (23%) patients. Furazolidone was mainly used in first- (79%) and second-line (21%) regimens. The methods used to diagnose H. pylori infection were: histology (81%), stool antigen test (64%), 13C-urea breath test (6.6%), and rapid urease test (1.9%). The mITT effectiveness of sequential therapy was 100%; 93% with the triple therapy and 75.5% with quadruple therapy. Compliance was reported in 98% of cases. Adverse events were revealed in 5.7% of patients, mostly nausea (3.8%). No serious adverse events were reported. Conclusion. Furazolidone containing eradication regimens appear to be an effective and safe empirical therapy in Russia

Calculation of Protolytic Equilibria Parameters on a Surface of Some Carbon Adsorbents According to Potentiometric Titration Data

Constants and Gibbs energy values of neutralization were calculated for protolytic equilibria on carbon adsorbents based on anthracite, charcoal and brown coal. A proposal regarding composition of surface functional groups of these sorbents was made

Elastīgas sijas škērstrieciena pētījums

50. RTU Studentu zinātniskās un tehniskās konferences materiāl

Anion Exchange Recovery of Gold (I) from Thiocyanate Solutions in the Presence of Iron (III), Silver (I) and Some Non Ferrous Metal Ions

We investigate ion exchange equilibria of thiocyanate complexes of gold (I), iron (III), copper (II) and zinc (II) during sorption from individual solutions on anion exchangers AV-17-8, AM-2B and AN-251 (commercial samples made in Russia). It was found out that there is a dependency between the basicity of anion exchangers and the selectivity of gold (I) recovery from thiocyanate multicomponent solutions (at simultaneous presence of Fe (III), Cu (II), Zn (II) and Ag (I) ions). As a result, the sorption sequences for thiocyanate metal complexes were obtained

Сорбционное извлечение платины (IV) из солянокислых растворов в присутствии железа (III), меди (II) и цинка

The present work is devoted to sorption preconcentration of platinum (IV) in the presence of iron (III), copper (II) and zinc from chloride solutions on the samples of CYBBER – new samples of ion exchangers. The initial concentrations of platinum, iron and non-ferrous metal ions were 0.25, 0.5 and 2.0 mmol/L, respectively. The acidity of the investigated solutions was 0.01 – 2 mol/L. It was shown that the ion exchangers possess high sorption ability to the noble metal ions, and allow the quantitative recovery of these ions. It was also found out that platinum can be isolated from the accompanying components by means of separate elution with 0.001 M HCl (iron ions), 0.5 M HNO3 (non-ferrous metal ions) and thiourea solution (80 g/L) in 0.3 M H2SO4 (platinum ions)Исследовано сорбционное концентрирование платины (IV) в присутствии железа (III), меди (II) и цинка из хлоридных растворов на новых образцах ионитов марки CYBBER. Исходные концентрации ионов платины, железа, меди и цинка составили соответственно 0.25, 0.5 и 2.0 ммоль/л. Кислотность исследуемых растворов 0.01 – 2 моль/л. Показана высокая сорбционная способность исследуемых ионитов к ионам благородного металла, что позволяет осуществить их количественное извлечение. Установлено, что платину можно отделить от сопутствующих компонентов путем раздельного элюирования при помощи 0.001 М HCl (ионы железа), 0.5 М HNO3 (ионы цветных металлов) и раствора тиомочевины (80 г/л) в 0.3 М H2SO4 (ионы платины

Kinetics of Simultaneous Recovery of Platinum (II,IV) and Rhodium (III) from Sulfate-Chloride Solutions on some Anion Exchangers

The paper is devoted to the kinetics of sorption concentration of platinum (II,IV) and rhodium (III) in their simultaneous presence in freshly prepared or stored sulfate-chloride solutions on some macroporous anion exchangers with different chemical structure. It was shown that the process rate is high, although it is slightly reduced in case of stored solutions. The rate of platinum sorption concentration in the presence of rhodium on investigated resins is higher than of rhodium in the presence of platinum. The sorption process was controlled by gel diffusion for all the anion exchangers studied.Изучена кинетика сорбционного концентрирования платины (II,IV) и родия (III) при совместном присутствии из свежеприготовленных и выдержанных сульфатно-хлоридных растворов некоторыми макропористыми анионитами различной химической структуры. Показана высокая скорость протекания этого процесса, которая несколько снижается при выдерживании растворов. Скорость сорбционного концентрирования платины в присутствии родия на исследуемых сорбентах превышает таковую для родия в присутствии платины. Сорбционный процесс контролируется гелевой диффузией для всех изученных анионитов

Calculation of Protolytic Equilibria Parameters on a Surface of Some Carbon Adsorbents According to Potentiometric Titration Data

Constants and Gibbs energy values of neutralization were calculated for protolytic equilibria on carbon adsorbents based on anthracite, charcoal and brown coal. A proposal regarding composition of surface functional groups of these sorbents was made