The permeability of reconstituted nuclear pores provides direct evidence for the selective phase model.

Nuclear pore complexes (NPCs) maintain a permeability barrier between the nucleus and the cytoplasm through FG-repeat-containing nucleoporins (Nups). We previously proposed a “selective phase model” in which the FG repeats interact with one another to form a sieve-like barrier that can be locally disrupted by the binding of nuclear transport receptors (NTRs), but not by inert macromolecules, allowing selective passage of NTRs and associated cargo. Here, we provide direct evidence for this model in a physiological context. By using NPCs reconstituted from Xenopus laevis egg extracts, we show that Nup98 is essential for maintaining the permeability barrier. Specifically, the multivalent cohesion between FG repeats is required, including cohesive FG repeats close to the anchorage point to the NPC scaffold. Our data exclude alternative models that are based solely on an interaction between the FG repeats and NTRs and indicate that the barrier is formed by a sieve-like FG hydrogel

Использование численной модели прогноза погоды WRF при моделировании развития аварийных ситуаций на Белорусской АЭС

The expediency of using Weather Research and Forecasting (WRF) numerical weather forecast model as a source of meteorological data during modeling of radioactive substances transfer in the atmosphere is considered, WRF technical details are briefly described. As the reference emergency scenario, the scenario of the maximum design accident hypothetically occurring at Belarusian Nuclear Power Plant (BelNPP) 12 UTC 21.03.2021 was chosen. Four numerical experiments with Global Forecast System (GFS) and WRF meteorological data and RIMPUFF and LASAT atmospheric diffusion models were performed in JRODOS Decision Support Systems (DSS). For each experiment, maps of underlying surface potential radioactive contamination of I131 were created. The potential contamination of the underlying surface I131 from 5 to 100 km from the BelNPP was assessed. The dependency graph of the maximum underlying surface contamination with I131 on the distance from the BelNPP was plotted based on the experiments results. The obtained results indicate the prospects of using the WRF meteorological model in the DSS at various stages of the emergency situations development at the BelNPP. Рассмотрена возможность использования численной модели прогноза погоды Weather Research and Forecasting (WRF) как источника метеорологических данных при моделировании переноса радиоактивных веществ в атмосфере, обозначены технические детали использования WRF. Для моделирования аварийной ситуации был выбран сценарий максимальной проектной аварии, гипотетически произошедшей в 12.00 на Белорусской АЭС (БелАЭС) 21 марта 2021. Четыре численных эксперимента с метеорологическими данными Global Forecast System (GFS) и WRF и моделями атмосферной диффузии RIMPUFF и LASAT были выполнены в системах поддержки принятия решений JRODOS. Для каждого эксперимента созданы карты потенциального радиоактивного загрязнения подстилающей поверхности I131. Проанализировано потенциальное загрязнение подстилающей поверхности I131 на расстоянии от 5 до 100 км от БелАЭС. Построен график зависимости максимального загрязнения I131 подстилающей поверхности от расстояния от БелАЭС для проведенных экспериментов. Полученные результаты свидетельствуют о перспективности использования метеорологической модели WRF в системах поддержки принятия решений на различных стадиях развития аварийных ситуации на БелАЭС

Использование численной модели прогноза погоды WRF при моделировании развития аварийных ситуаций на Белорусской АЭС

The expediency of using Weather Research and Forecasting (WRF) numerical weather forecast model as a source of meteorological data during modeling of radioactive substances transfer in the atmosphere is considered, WRF technical details are briefly described. As the reference emergency scenario, the scenario of the maximum design accident hypothetically occurring at Belarusian Nuclear Power Plant (BelNPP) 12 UTC 21.03.2021 was chosen. Four numerical experiments with Global Forecast System (GFS) and WRF meteorological data and RIMPUFF and LASAT atmospheric diffusion models were performed in JRODOS Decision Support Systems (DSS). For each experiment, maps of underlying surface potential radioactive contamination of I 131 were created. The potential contamination of the underlying surface I 131 from 5 to 100 km from the BelNPP was assessed. The dependency graph of the maximum underlying surface contamination with I 131 on the distance from the BelNPP was plotted based on the experiments results. The obtained results indicate the prospects of using the WRF meteorological model in the DSS at various stages of the emergency situations development at the BelNPP

Совершенствование методики классификации уровня пожарной опасности в лесах с использованием метеорологических и аэрокосмических данных

The article proposes improvements to the method for determining the fire hazard level in forests based on predictive meteorological and aerospace data. A brief analysis of various methods for the fire hazard level determining in forests and the sets of initial parameters used in this case was carried out in order to determine the final method's optimal characteristics and properties for further application. The calculation of the fire hazard assessment is based on the flammability basic indicator according to weather conditions and correction factors based on the vegetation indices values. Vegetation indices division into quartiles is proposed for a vegetation relative assessment in the territory under consideration. Maps of the forest blocks distribution by fire hazard classes for the Volozhinsky forestry enterprise territory were obtained according to the proposed and other methods. A comparative analysis of the numerical and spatial characteristics of the obtained assessments of forests fire hazard using various methods was carried out. According to the improved methodology assessment results, its application results correlate with the assessment according to the standardized methodology, but adjusted according to the vegetation assessment results. It is advisable to verify the proposed methodology during a fire hazard period in real conditions, followed by an assessment of the results and refinement if necessary.В статье предлагаются усовершенствования методики определения уровня пожарной опасности в лесах на основе прогнозных метеорологических и аэрокосмических данных. Проведен краткий анализ различных методик определения уровня пожарной опасности в лесах и используемых при этом наборов исходных параметров с целью определения оптимальных характеристик и свойств конечной методики для дальнейшего применения. Расчет оценки пожароопасности производится на основе базового показателя горимости по условиям погоды и корректирующих коэффициентов по значениям вегетационных индексов. Предложено разбиение вегетационных индексов по квартилям для относительной оценки растительности на рассматриваемой территории. Получены карты распределения лесных кварталов по классам пожарной опасности для территории Воложинского лесхоза согласно предложенной и иным методикам. Проведен сравнительный анализ численных и пространственных характеристик полученных оценок пожарной опасности в лесах по различным методикам. Согласно результатам оценки усовершенствованной методики, результаты ее применения коррелируют с оценкой согласно стандартизованной методике, позволяя скорректировать ее по результатам оценки растительности. Целесообразна верификация предложенной методики в пожароопасный период в реальных условиях с последующей оценкой результатов и доработкой в случае необходимости

Nanoscale stiffness topography reveals structure and mechanics of the transport barrier in intact nuclear pore complexes

The nuclear pore complex (NPC) is the gate for transport between the cell nucleus and the cytoplasm. Small molecules cross the NPC by passive diffusion, but molecules larger than ∼5 nm must bind to nuclear transport receptors to overcome a selective barrier within the NPC1. Although the structure and shape of the cytoplasmic ring of the NPC are relatively well characterized2, 3, 4, 5, the selective barrier is situated deep within the central channel of the NPC and depends critically on unstructured nuclear pore proteins5, 6, and is therefore not well understood. Here, we show that stiffness topography7 with sharp atomic force microscopy tips can generate nanoscale cross-sections of the NPC. The cross-sections reveal two distinct structures, a cytoplasmic ring and a central plug structure, which are consistent with the three-dimensional NPC structure derived from electron microscopy2, 3, 4, 5. The central plug persists after reactivation of the transport cycle and resultant cargo release, indicating that the plug is an intrinsic part of the NPC barrier. Added nuclear transport receptors accumulate on the intact transport barrier and lead to a homogenization of the barrier stiffness. The observed nanomechanical properties in the NPC indicate the presence of a cohesive barrier to transport and are quantitatively consistent with the presence of a central condensate of nuclear pore proteins in the NPC channel

Viruses Challenge Selectivity Barrier of Nuclear Pores

Exchange between the nucleus and the cytoplasm occurs through nuclear pore complexes (NPCs) embedded in the double membrane of the nuclear envelope. NPC permeability barrier restricts the entry of inert molecules larger than 5 nm in diameter but allows facilitated entry of selected cargos, whose size can reach up to 39 nm. The translocation of large molecules is facilitated by nuclear transport receptors (NTRs) that have affinity to proteins of NPC permeability barrier. Viruses that enter the nucleus replicate evolved strategies to overcome this barrier. In this review, we will discuss the functional principles of NPC barrier and nuclear transport machinery, as well as the various strategies viruses use to cross the selective barrier of NPCs

Silvicultural efficiency of herbicides application as a growth inhibitor of herbaceous plants after strip-gradual felling

Currently in forestry weeding is widely used by way of mowing round, but as a result of it a significant portion of undergrowth is damaged. Application of herbicides in areas where weeding is planed helps to increase the safety of commercially valuable species undergrowth and reduce presence in the composition of undesirable deciduous species