bluuebunny/crossref_metadata_2025 huggingface dataset:
The Asynergies of Structural Disaster Risk Reduction Measures: Comparing Floods and Earthquakes
Authors: de Ruiter Marleen C. , de Bruijn Jens A. , Englhardt Johanna , Daniell James E. , de Moel Hans , Ward Philip J.
Published: December 2020

Traditionally, building‐level disaster risk reduction (DRR) measures are aimed at a single natural hazard. However, in many countries the society faces the threat of multiple hazards. Building‐level DRR measures that aim to decrease earthquake vulnerability can have opposing or conflicting effects on flood vulnerability, and vice versa. In a case study of Afghanistan, we calculate the risk of floods and earthquakes, in terms of average annual losses (AAL), in the current situation. Next, we develop two DRR scenarios, where building‐level measures to reduce flood and earthquake risk are implemented. We use this to identify districts for which DRR measures of one hazard increase the risk of another hazard. We then also calculate the optimal situation between the two scenarios by, for each district, selecting the DRR scenario for which the AAL as a ratio of the total exposure is lowest. Finally, we assess the sensitivity of the total risk to each scenario. The optimal measure differs spatially throughout Afghanistan, but in most districts it is more beneficial to take flood DRR measures. However, in the districts where it is more beneficial to take earthquake measures, the reduction in risk is considerable (up to 40%, while flood DRR measures lead to a reduction in risk by 16% in individual districts). The introduction of asynergies between DRR measures in risk analyses allows policy‐makers to spatially differentiate building codes and other building‐level DRR measures to address the most prevalent risk while not compromising the risk resulting from other hazards.
Concentric Secondary Gravity Waves in the Thermosphere and Ionosphere Over the Continental United States on March 25–26, 2015 From Deep Convection
Authors: Vadas Sharon L. , Azeem Irfan
Published: December 2020

We examine the total electron content (TEC) from GPS receivers over the United States on March 25–26, 2015. We observe partial to nearly fully concentric rings of traveling ionospheric disturbances (TIDs) with centers close to deep convection. Many of these TIDs have observed horizontal phase speeds cH > 300 m/s, suggesting they are induced by gravity waves (GWs) created in the thermosphere. We investigate the largest‐amplitude concentric TIDs at 23:00 UT on March 25 and 01:20 UT on March 26. We find that cH and the GW period τr increase linearly with radius and the horizontal wavelength, λH, increases quadratically with radius. This is expected if the GWs are excited by point sources. For these GWs, cH = 150–530 m/s, τr ∼ 8–40 min, and λH ∼ 100–500 km. Using reverse ray‐tracing, no GW with cH > 200 m/s propagates below z = 100 km, 73% of the GWs in the first case cannot propagate below z ∼ 100 km, all of the GWs in the second case cannot propagate below z ∼ 100 km, and the inferred thermospheric point sources are ∼2–4° from deep convection. Because the underlying GWs are most likely excited by a point source and most must be created in the thermosphere, we find that these concentric TIDs are most likely induced by GWs generated in the thermosphere, including those with cH = 150–200 m/s. Their close proximity to deep convection and the TEC map asymmetries suggest these TIDs are likely induced by secondary GWs from local horizontal body forces created by the dissipation of primary GWs from deep convection.
Influence of Hurricane Wind Field Variability on Real‐Time Forecast Simulations of the Coastal Environment
Authors: Rey Alexander J. M. , Mulligan Ryan P.
Published: December 2020

Dynamic conditions occur in the coastal ocean during severe storms. Forecasting these conditions is challenging, and large‐scale numerical models require significant computing power. In this paper, we describe a real‐time modeling system (DUNEX‐RT), developed in support of the During Nearshore Event experiment (DUNEX) off the coast of North Carolina, United States of America. The model is run with wave, current, and water level boundary conditions from larger‐scale models, and provides 36‐h forecasts of significant wave height, depth‐averaged velocity, and water levels every 6‐h using Delft3D‐SWAN. Observations and forecasts run at different times are compared and communicated via an interactive website to verify model performance in real‐time and to visualize uncertainty from changing inputs. Here, we evaluate model sensitivity to inputs from seven different atmospheric hindcasts and two atmospheric forecasts for Hurricane Dorian in September 2019. The results emphasize the importance of accurate wind forcing, with significant differences observed between the output model results for different input atmospheric forcing models and forecasts produced at different times. The best results were achieved using atmospheric forcing from the high resolution rapid refresh model, and overall, DUNEX‐RT had low errors at 33 wave, water level, and current sites across the system. The model results for water levels and significant wave heights were also accurate over a longer period of 49 days. Overall, the good forecast skill achieved for the wide range of conditions over this time results suggest that this high‐resolution regional approach could be applied to forecast conditions in other coastal areas.
Independent Eddy Identification With Profiling Argo as Calibrated by Altimetry
Authors: Chen Ge , Chen Xiaoyan , Huang Baoxiang
Published: December 2020

Thousands of mesoscale eddies are now routinely tracked on daily basis in the global ocean, thanks to the state of the arts technology of tandem satellite altimetry. Despite the obvious success, it has been recently recognized that a substantial portion of oceanic eddies may still be missed out due to inadequate spatiotemporal sampling by available altimeters. As an effort to tackle this problem, we propose a methodology to effectively expand the capacity of eddy tracking by using altimetrically “calibrated” Argo measurements. The idea is to develop an independent identification scheme which relates eddy surface signature to its interior property based on the fact that sea surface topography detected by altimetry is highly correlated to the vertical structure of potential density anomaly derived from Argo profiles. Among the nearly 4,000 active Argo floats about one third are found to fall into altimeter‐captured eddies, and roughly one fourth additional floats are identified by the verified Argo‐alone criteria as onboard eddies outside altimetrically derived ones (i.e., which would otherwise be overlooked by altimeters). In particular, Argo‐based eddy identification is found to compensate that of altimetry by partially rectifying its ineffectiveness in low latitude areas, as well as its misclassification of eddy polarity oceanwide which accounts for 4.3% of the altimeter‐identified eddy population.
Submesoscale Phenomena Due to the Brazil Current Crossing of the Vitória‐Trindade Ridge
Authors: Napolitano D. C. , da Silveira I. C. A. , Tandon A. , Calil P. H. R.
Published: December 2020

At 20.5°S, the Brazil Current and the Intermediate Western Boundary Current interact with a quasi‐zonal seamount chain, the Vitória‐Trindade Ridge (VTR). While the mesoscale variability generated due to these western boundary currents crossing the VTR has been recently studied, the submesoscale dynamics associated with such features have never been addressed. Here, we use new observations and a 2‐ km‐resolution model to analyze the role of the VTR seamounts in the regional submesoscale dynamics, their seasonality, and instabilities. We present new high‐resolution velocity and density observations that capture submesoscale features associated with the flow. Within these regions, potential vorticity (PV) reveals patches of symmetrically unstable flow close to seamounts. The horizontal resolution (Δx ≃ 1.5 km) of our quasi‐synoptic observations (10 h) partially resolves submesoscale instabilities. Our Regional Oceanic Modeling System simulation identifies two regimes of submesoscale activity in the region, one typically associated with the seasonal cycle of the mixed layer, and a second associated with flow–topography interactions. A spatiotemporal analysis of the vertical buoyancy fluxes points to these flow–topography interactions as the main source of recurrent, deeper instabilities. As the VTR emerges as a submesoscale hotspot in the oligotrophic South Atlantic, the lack of observations still remains the main obstacle to better understand submesoscale processes in the region.
Assessing Uncertainties and Approximations in Solar Heating of the Climate System
Authors: Hsu Juno C. , Prather Michael J.
Published: December 2020

In calculating solar radiation, climate models make many simplifications, in part to reduce computational cost and enable climate modeling, and in part from lack of understanding of critical atmospheric information. Whether known errors or unknown errors, the community's concern is how these could impact the modeled climate. The simplifications are well known and most have published studies evaluating them, but with individual studies it is difficult to compare. Here, we collect a wide range of such simplifications in either radiative transfer modeling or atmospheric conditions and assess potential errors within a consistent framework on climate‐relevant scales. We build benchmarking capability around a solar heating code (Solar‐J) that doubles as a photolysis code for chemistry and can be readily adapted to consider other errors and uncertainties. The broad classes here include: use of broad wavelength bands to integrate over spectral features; scattering approximations that alter phase function and optical depths for clouds and gases; uncertainty in ice‐cloud optics; treatment of fractional cloud cover including overlap; and variability of ocean surface albedo. We geographically map the errors in W m−2 using a full climate re‐creation for January 2015 from a weather forecasting model. For many approximations assessed here, mean errors are ∼2 W m−2 with greater latitudinal biases and are likely to affect a model's ability to match the current climate state. Combining this work with previous studies, we make priority recommendations for fixing these simplifications based on both the magnitude of error and the ease or computational cost of the fix.
Sphingosine kinase 1 regulates HMGB1 translocation by directly interacting with calcium/calmodulin protein kinase II-δ in sepsis-associated liver injury
Authors: Tian Tao , Yao Danhua , Zheng Lei , Zhou Zhiyuan , Duan Yantao , Liu Bin , Wang Pengfei , Li Yousheng
Published: December 2020

Previously, we confirmed that sphingosine kinase 1 (SphK1) inhibition improves sepsis-associated liver injury. High-mobility group box 1 (HMGB1) translocation participates in the development of acute liver failure. However, little information is available on the association between SphK1 and HMGB1 translocation during sepsis-associated liver injury. In the present study, we aimed to explore the effect of SphK1 inhibition on HMGB1 translocation and the underlying mechanism during sepsis-associated liver injury. Primary Kupffer cells and hepatocytes were isolated from SD rats. The rat model of sepsis-associated liver damage was induced by intraperitoneal injection with lipopolysaccharide (LPS). We confirmed that Kupffer cells were the cells primarily secreting HMGB1 in the liver after LPS stimulation. LPS-mediated HMGB1 expression, intracellular translocation, and acetylation were dramatically decreased by SphK1 inhibition. Nuclear histone deacetyltransferase 4 (HDAC4) translocation and E1A-associated protein p300 (p300) expression regulating the acetylation of HMGB1 were also suppressed by SphK1 inhibition. HDAC4 intracellular translocation has been reported to be controlled by the phosphorylation of HDAC4. The phosphorylation of HDAC4 is modulated by CaMKII-δ. However, these changes were completely blocked by SphK1 inhibition. Additionally, by performing coimmunoprecipitation and pull-down assays, we revealed that SphK1 can directly interact with CaMKII-δ. The colocalization of SphK1 and CaMKII-δ was verified in human liver tissues with sepsis-associated liver injury. In conclusion, SphK1 inhibition diminishes HMGB1 intracellular translocation in sepsis-associated liver injury. The mechanism is associated with the direct interaction of SphK1 and CaMKII-δ.
Gastrointestinal Interventions: Then and Now
Authors: LoGiurato Brendan , Smirniotopoulos John , Darcy Michael , Charalel Resmi A.
Published: December 2020

Gastrointestinal interventions have continuously evolved since the inception of interventional radiology. This article will review major milestones in this evolution including the introduction of new tools, the development of new procedures, and the establishment of interventional radiology as its own clinical specialty. Together, these milestones have helped shape how interventional radiologists perform gastrointestinal interventions today.
A review and refinement of the concept of containment for the management of invasive plants
Authors: Grice A. C. , Murphy H. T. , Clarkson J. R. , Friedel M. H. , Fletcher C. S. , Westcott D. A.
Published: December 2020

Containment is a frequently advocated strategic objective for countering plant invasions. It is commonly perceived that it is the valid fall-back option when eradication has failed or is deemed impossible with the available resources. We reviewed management and research literature on containment. The lack of a clear, universally accepted definition of containment is problematic and containment practice is not well aligned with the limited research literature. Vague and inconsistent use of the term, poorly developed relationships between management practice and the ecological drivers of invasion, and frequent failure to specify appropriately scaled spatial configurations in management strategies make it difficult to evaluate containment as a strategy, generally or in specific cases. Management strategies rarely provide the basis for effective and efficient containment programs and this may reflect a lack of under-pinning scientific principles. We recommend that containment be defined as ‘deliberate action taken to prevent establishment and reproduction of a species beyond a predefined area’ and suggest that containment efforts should focus on individual infestations or populations but simultaneously cover all infestations or populations that are separated from one another by habitat suitable for the species. Containment units should be rigorously defined but the inevitability of breaches of these containment units, due to the stochastic nature of dispersal, implies that containment generally requires a capacity for local eradication (extirpation). This means that many infestations are no more amenable to containment than to eradication. The measures we propose would improve assessment of the feasibility and success of containment strategies.
Effect of Epichloë gansuensis endophyte on rhizosphere bacterial communities and nutrient concentrations and ratios in the perennial grass species Achnatherum inebrians during three growth seasons
Authors: Hou Wenpeng , Xia Chao , Christensen Michael J. , Wang Jianfeng , Li Xiuzhang , Chen Tao , Nan Zhibiao
Published: December 2020

Achnatherum inebrians is an invasive perennial grass widespread in natural grasslands of north-west China and plays an important role in grassland ecological restoration. The presence of the seed-borne endophytic fungus Epichloë gansuensis in A. inebrians promotes grass growth, increases resistance to abiotic stress, and affects the rhizosphere microbial community of host plants. However, the relationships among E. gansuensis, rhizosphere bacteria and plant contents of carbon (C), nitrogen (N), phosphorus (P) and potassium (K) during different growing seasons are not clear. We examined changes in the rhizosphere bacterial community and in nutrient contents and ratios in A. inebrians with (E+) and without (E−) E. gansuensis in May, August and December. The Shannon diversity index was higher for rhizosphere bacteria of E+ than E− plants in the three different seasons. Leaf C, N and P contents and root P and K contents were higher in E+ than E− plants in May, and leaf K and root C were higher in E+ than E− plants in August. Leaf C:N ratios were lower in E+ than E− plants in December, and leaf C:K ratios were lower in E+ than E− plants in August and December. In addition, our results indicate significant interactions among rhizosphere bacteria, C, N, P and K contents, and endophyte treatment in three different seasons. In conclusion, E. gansuensis enhanced the C, N, P and K contents of host plants, and affected nutrient ratios of A. inebrians probably by increasing rhizosphere bacterial diversity and altering rhizosphere bacterial community structure. This study provides new findings on the ecological function of the endophyte E. gansuensis, including its potential role in enhancing soil fertility. The improvements in soil fertility were utilised in extrapolating to forage grass–endophyte associations.
Optimising grazing for livestock production and environmental benefits in Chinese grasslands
Authors: Badgery Warwick B. , Kemp David , Yingjun Zhang , Zhongwu Wang , Guodong Han , Fujiang Hou , Nan Liu , Michalk David , Behrendt Karl
Published: December 2020

Overgrazing has extensively degraded Chinese grasslands. A reduction in stocking rate of 30–50% below the district averages is required to increase the profitability of livestock production and protect vital ecosystem services such as mitigation of greenhouse gases (GHG). Grazing experiments located in the desert steppe, typical steppe and alpine meadow verified the influence of stocking rate and grazing management on livestock production, grassland composition and associated ecosystem services. The desert steppe experiment found lower stocking rates of ~150 SE (where SE is sheep equivalent, which is a 50kg animal) grazing days ha–1 (1 SE ha–1 over 150 days) enhanced botanical composition, maintained profitable lamb growth rates and reduced GHG emissions intensity. The typical steppe experiment found moderate grazing pressure of ~400 SE grazing days ha–1 (4 SE ha–1 over 100 days) maintained higher lamb growth rates, an average herbage mass >0.5t DM ha–1 that maintained the content of Leymus chinensis above 70% and Artemisia frigida below 10% of the grassland and had the highest level of net carbon sequestration. In the alpine meadow experiment the district average stocking rate of ~16 SE ha–1 (1440 SE grazing days ha–1 over 90 days) was not too high, but extending grazing into the non-growing season had no benefit. The findings of these experiments highlight that many of the benefits to ecosystem services can be achieved with reduced stocking rates which also generate profitable levels of livestock production. In both the desert and typical steppe experiments, the results were optimal when the stocking rates were adjusted to maintain average herbage mass over summer above ~0.5t DM ha–1, whereas herbage mass was higher with the local, conservative stocking rates in the alpine meadow.
Mendeleev’s law and Chicherin’s atomic nucleus
Authors: Kharitonov V V , Ezhov A A
Published: December 2020

The XVII International Conference and the School of Young Scientists “Physical and Chemical Processes in Atomic Systems” were dedicated to the 150th anniversary of the Mendeleev Periodic Table of Chemical Elements. Here we want to draw attention to the influence of Mendeleev’s discovery on the development of the first model of the atom, assuming the existence of a nucleus in it. Historically, atomic models were developed on the basis of modern experimental data. W. Thomson’s model (1902) uses the discovery of electrons by J.J. Thomson. Nagaoka’s (1904) model derives the finite size of atomic nuclei from optical spectra, and Rutherford’s (1911) model finds the actual size of nuclei from experimental alpha scattering data. In this work, we recall that it was Boris Nikolaevich Chicherin who proposed the earliest model that assumed the existence of an atomic nucleus. This model was published in a series of articles in the journal of the Russian physio-chemical society in 1887-1892. The model was based on a complex mathematical analysis of Mendeleev’s law, specifically on the periodicity of experimental data associated with atomic specific volumes, and made it possible to predict the existence of a central positively charged nucleus and a negatively charged periphery of an atom. We must pay tribute to Chicherin and recognize his model as the earliest model of the atom, assuming the presence of an atomic nucleus in it.
Numerical study on coupling mode of mechanical and thermal drive
Authors: Gu Zhiyong , Jiang Dongjun , Borisevich V D , Zeng Si
Published: December 2020

In modern gas centrifuge (GC), circulations driven by stationary scoops and temperature difference between end caps, also called as mechanical and thermal drive circulations, have very important effects on its separation performance. The flow patterns of mechanical and thermal drive circulations in a GC are different and whether the coupling mode of them is linear or nonlinear is not clear. In this research, an axial circulation in the model Iguassu GC is simulated for single mechanical, thermal, and both kind together drives. In addition, the product and waste baffles are also considered in the model GC, making the flow patterns much more complicated. The conditions of rotors with different aspect ratios are also investigated. We take the absolute value of the stream function along an axial cross section to define the intensity of various types of axial circulations. The simulation results demonstrate that the coupling mode of mechanical and thermal drive circulations in a GC is close to linear even though the circulations are reshaped by product and waste baffles. The result obtained may simplify the procedure of optimization for the separative power of a single GC for isotope separation.
Separation of boron isotopes in optimal cascade of uniflow gas centrifuges
Authors: Palkin V A , Lubnin S S , Tokmantsev V I
Published: December 2020

Was considered a problem of an optimization of concurrent gas centrifuges for separation of Boron isotopes in form of trifluoride BF3. As the criteria was used a minimum of total number of gas centrifuges upon the given external parameters of the cascades’ scheme. The method is based on the analytical relationships for the flows of stages, received under approximating minimization of the total feed flow. Conducted cascade calculations showed that it is possible to obtain BF3 with enrichment up to 99.9 % of 10B in the selection and up to 0.1 % in the waste, which is equivalent to 99.9 % of 11B.
Centrifugal Separation of Carbon Isotopes Using Carbon Tetrafluoride as Processing Gas
Authors: Sun Q , Jian C , Zhou M , Pei G
Published: December 2020

At present, the application of carbon isotope is becoming more and more extensive, especially in the field of medical testing, and the demand for 13C in high abundance is fast increasing. Using carbon tetrafluoride (CF4) as separation medium, study on centrifugal separation of carbon isotopes was carried out. Single-centrifuge experiments were done based on modified domestic gas centrifuges. As a result, the separation factor and single-centrifuge separative power under different working conditions were obtained. Based on the results of single-centrifuge separation experiments, cascade calculation of the enrichment of 13C isotope was conducted by ideal cascade. According to calculation results, through two cascade separations, 13C isotope could be enriched from 30% to above 99% in abundance. The study laid a good basement for production of 13C isotope in high abundance.
Influence of changing feed flow value on germanium isotope separation in gas centrifuge cascade
Authors: Ushakov A A , Orlov A A , Zaviryukha M A
Published: December 2020

Modeling of a nonstationary process caused by changing the cascade feed flow value using germanium isotope separation as an example. During a nonstationary process, the concentrations of isotopes with intermediary mass number in light and heavy fraction flows may cross the range limits restricted by the initial and final stationary values and exceed the maximum reachable values for a three-flow cascade. Time for stationary isotope concentrations to settle is different for isotopes and depends on the final values of cascade flow.
Economic estimation of boron isotope production by gas diffusion method using BF3 as processing gas
Authors: Wang Y B , Pei G , Jiang D J , Zhou M S
Published: December 2020

Natural occurring boron has two stable isotopes: boron-10 and boron-11. Boron-10 has high thermal neutron cross section in a wide range of energy and the product of boron-10’s neutron reaction contains alpha particles. So, it is a good material for neutron absorbing and neutron detecting. In order to enrich boron-10 from natural boron, several methods had been proven to be feasible: chemical exchange distillation, cryogenic distillation and ion exchange resin method. The market now places higher demands on the economics of the separation method, so study on production of boron-10 by gas diffusion method is carried out. Using BF3 as processing gas, it is feasible to enrich high abundance of boron-10 by gas diffusion. The single stage separation effect and the hydraulic status of single stage was estimated. Binary gas diffusion cascades were designed and compared. Under given production requirements, the scale of the cascade was estimated and optimized. Finally, step cascade was picked for the production of 96% boron-10. Based on the cascade design, economic estimation of this separation method was conducted, and the target product cost was calculated. This study laid a good foundation for the expansion of boron isotope separation methods.
Peculiar properties of transient processes in cascades with additional product flow
Authors: Mustafin A R , Smirnov A Yu , Sulaberidze G A , Borisevich V D , Zeng S , Jiang D
Published: December 2020

One of the important stages in the campaign for separation of multicomponent isotopic mixtures is bringing the separation cascade to a stationary mode of operation. This process, depending on the applied separation method, can be characterized by a relatively long time with associated consumption of the working substance and operating costs. Therefore, the search for the values of the control parameters of the cascade at which it is possible to reduce the transient process time is practically a significant problem in the theory of isotope separation in cascades. One of the current trends in the modern theory of cascades is the study of physical laws of stationary mass transfer in cascades with additional outgoing flows. Such cascades can find application for solving a number of urgent problems, in particular, obtaining relatively high concentrations of isotopes with intermediate masses. At the same time, the laws of unsteady mass transfer in such cascades remain poorly understood. The paper analyses the key patterns of transient processes in a square cascade with an additional product flow. The interconnections between the time of bringing such a cascade to the stationary mode and the external conditions under which the process of separation of the mixture occurs are revealed.
Multy-cascade enrichment schemes for reprocessed uranium recycling
Authors: Gusev V E
Published: December 2020

This paper deals with the problem of reprocessed uranium (RepU) enrichment in cascades of gas centrifuges with simultaneous fulfillment of requirements on concentrations of isotopes 232,234,236U. These harmful isotopes bred by nuclear chain reaction are responsible for an increase in radioactivity level and neutron poisoning of fresh nuclear fuel. The study examines the cascade schemes that aim at closing the nuclear fuel cycle by satisfying the formal condition of the complete uranium reclaim. The prospective VVER fuel cycle strategy of multiple uranium recycling is considered. Schemes under consideration are multi-cascade ones. Such configurations are necessary to fulfill both a series of requirements on concentrations of even-numbered isotopes in commercial low-enriched uranium and condition of ‘full return’ of uranium extracted from spent nuclear fuel from particular reactor to produce fresh fuel load for the same reactor. The research provides a basis for comparison between three various multi-cascade schemes designed to re-enrich RepU under mentioned above conditions. The unified metrics (related to ordinary cascade and normalized to LEU product) of natural uranium savings, separative work, and depleted uranium consumption and their derivative, we used. The calculations take into account the necessity of RepU dilution to compensate for the adverse effects of 232,234,236U isotopes. As the reference cascade scheme, a simple modification of a single triple-flow cascade for RepU enrichment was considered. It is demonstrated that some modern cascade schemes could provide repetitious recycling of uranium.
Optimization of a system of square cascades for efficient concentration of intermediate isotopes
Authors: Azizov T E , Smirnov A Yu , Sulaberidze G A , Mustafin A R
Published: December 2020

The problem of obtaining relatively high concentrations of stable isotopes of intermediate mass numbers is considered. The object of research is a connection of three ordinary square cascades. The possibility of simultaneous concentration of isotopes of intermediate masses in different output flows of cascades is shown. The dependencies of the parameters of the cascade schemes under consideration are investigated. The method of optimization of such system of square cascades according to the criterion of minimum relative total flow at given concentrations of target components is proposed. Calculations were made on the example of isotope mixtures with the number of components 4 and 5.
Production of highly concentrated intermediate molybdenum isotopes in optimal cascade with two additional product flows
Authors: Palkin V A , Maslyukov E V , Lubnin S S
Published: December 2020

The problem of highly concentrated molybdenum isotopes production in multiflow cascades is considered. A method of the cascade with two additional product flows optimization has been developed. Two components intermediate in weight are concentrated simultaneously in those flows. The optimization problem is solved using a variation of the partial flow cuts of the cascade stages with large separation coefficients. The optimization criterion is the minimum of the stage total feed flow while ensuring a given concentration of isotopes. A computational experiment was carried out to separate a mixture of molybdenum hexafluoride. The experiment demonstrated the features of intermediate components concentrating in additional product flows of the cascade.
Optimal working regimes of the hyper-speed long Iguasu gas centrifuge
Authors: Bogovalov S.V. , Borman V.D. , Vasilyev A.V. , Tronin I.V. , Tronin V.N.
Published: December 2020

Rapid development of technologies for production of new materials may provide design of gas centrifuges (hereafter GC) with rotor speed above 1000 m/s. The question about efficiency of such GCs remains open. At present no experimental or theoretical studies regarding the separation effciency of such GCs exist. We present the results of calculations of the optimized separative power of the hyper-speed Iguassu GCs with a length of 1 to 5 meters and rotational speeds from 1000 to 1500 m/s. The calculations were performed in axisymmetric approximation in frameworks of the source-sink model. It is shown that for the hyper-speed GCs the optimized separative power, pressure at the rotor wall, feed flux and gas friction power linearly grow with the rotor length, while the temperature drop along the rotor does not depend on the rotor length.
Automatic optimization of working modes of a gas centrifuge for isotope separation
Authors: Juromskiy V M , Borisevich V D
Published: December 2020

The adaptive algorithms for the automatic search for the optimum separative power of a single gas centrifuge (GC) depending on the pressure of the working gas near the wall of the working chamber are studied. It is demonstrated that the proposed control system is insensitive to the displacement of the found optimum of the separative power, a change in the shape of the extremum, including deformation of the “plateau” in the maximum region, as well as the additive errors of the technical means measuring the GC separation ability
Production of high-enriched carbon-13 by two-stage laser method
Authors: Laptev V B , Pigulsky S V , Mezhevov V S
Published: December 2020

A variant of a two-stage laser process for production highly enriched carbon-13 (13C) with a concentration of more than 99% is being investigated. The first laser stage provides effective enrichment of 13C up to 30-50% based on the isotopically selective multiphoton dissociation of freon-22 (CF2HCl) by pulsed radiation of a CO2 laser. Then the product of the first stage tetrafluoroethylene, enriched in 13C, is converted into the working substance of the second stage, freon-12B2 (CF2Br2). At the second stage of enrichment, a component with an undesirable isotope 12C undergoes to selective dissociation, until its concentration in the residual gas decreases to 1% and the concentration of the 13C isotope is increased to 99%. In preliminary experiments, high parameters of the elementary act of separation were achieved - the dissociation yield of the 12CF2Br2 up to 20% and selectivity (for 12C) up to 100. A productivity of the second enrichment stage for a reactor of ideal displacement is estimated, that is 0.6 and 1.2 g13C/h for initial concentrations of 13CF2Br2 30 and 50%, respectively.
Application of the perturbation theory for the calculation of thermodynamic and transport properties of hydrogen and its isotopes
Authors: Bogdanova Yu A , Maklashova I V , Gubin S A , Vagina U D
Published: December 2020

In this paper, we analyzed the analytical relationships in the literature to calculate the viscosity coefficient obtained from the Chapman-Enskog kinetic theory using the Lennard-Jones pair interaction potential. In the proposed formulas for calculating the viscosity of individual substances, there are values of the radial distribution function and the hard-sphere diameter. These quantities were obtained using a technique developed previously by the authors based on the perturbation theory used to calculate the thermophysical properties of substances
Automatic system of temperature control at laser cladding
Authors: Glova A F , Lysikov A Yu , Nelyubin S S , Klochkov I D , Baldaev L K , Novinkin Yu A , Stogov M A
Published: December 2020

An automatic system for monitoring the true temperature of the surface of a heated body based on a small-sized spectrometer has been developed and created. The system operates in real time with a speed of 30 ms. The system has been tested in laboratory conditions and tested in pilot production with laser cladding of metal powder.
Controlled processes at laser coating deposition
Authors: Glova A F , Lysikov A Yu , Nelyubin S S , Klochkov I D , Baldaev L K , Novinkin Yu A , Stogov M A
Published: December 2020

A description of the method is given of coating deposition under irradiation with a horizontal laser beam of a gas-dust medium which is an ensemble of micro-particles moving in the gas in the form of a free vertical jet. A number of coatings are obtained on various substrates and the results of measurements of their characteristics are presented. A setup based on a cw CO2-laser for the synthesis of diamond coatings in optical discharge plasma in the laser plasmatron mode has been created. The effect of spherical lens aberrations on the discharge maintenance thresholds is established. A diamond film was obtained on the surface of a tungsten substrate when a plasma jet was expelled into atmospheric air. An automatic system for measuring surface temperature in real time has been developed and created. The system was tested for laser cladding of metal powder in a pilot production.
Impact of the pre-deposited surface charge on the breakdown in a dielectric barrier discharge in the air
Authors: Akishev Y , Karalnik V , Petryakov A , Shao T , Zhang C
Published: December 2020

The electrical charge deposited on a dielectric barrier of dielectric barrier discharge (DBD) changes markedly the configuration and strength of the local electric field both on the barrier and in the gas gap. In turn, a change in the local electric field affects the rate of ionization multiplication of electrons in this area and, accordingly, influences the breakdown conditions providing the appearance of microdischarges in a barrier discharge. The features of the DBD breakdown in the presence of the pre-deposited charge on a dielectric barrier were investigated by the example of the plane-to-plane DBD operating in the ambient air at atmospheric pressure. The electric charge deposition on the barrier was performed in advance with the use of the pulsed pin-to-plane barrier corona. Corona discharge allows one to control both the amount and location of the pre-deposited charge. The slow increasing voltage of the needed polarity was used to initiate the breakdown in the plane-to-plane DBD. The slow increasing applied voltage provides the multiple breakdowns forming the “one by one” sequence of MDs. The analysis of the obtained results was performed on the base of the conception of the necessary and sufficient conditions for the MDs formation.
Electron transport in dense degenerate plasmas
Authors: Filippov AV
Published: December 2020

Within a unified approach, a method for calculating the tensors of electrical conductivity, the Seebeck coefficient and thermal conductivity of a nonideal plasma in a magnetic field were considered. Under this unified approach the kinetic coefficients are calculated together with the equation of state for a nonideal plasma within the framework of a quasi-chemical model. Various methods for determining the Coulomb logarithm in the kinetic theory of transport and various options for choosing the boundary value of the wave number of electrons are considered. The scattering of electrons by ions using the phase shift method has been considered and the appearance of values of the Coulomb logarithm less than unity are demonstrated. Electron scattering by the phase shift method is considered using the Buckingham potential which permits to describe the Ramsauer minimum in the transport cross section for electron scattering by noble gas atoms.
Experimental studies of the electrical and radiative characteristics of a channel surface discharge
Authors: Kotov A A
Published: December 2020

Channel surface discharge (CSD) is a type of surface (sliding) discharges or dielectric barrier discharges in the incomplete stage. Experimental results of both incomplete (low-current) and high-current complete stages of the CSD are presented. The waveform of current pulse in the discharge incomplete stage as well as the influence of the voltage growth rate dU/dt on the discharge electrodes on waveform are studied. Experimental dependence of the CSD current pulse amplitude on the dU/dt rate is obtained in the incomplete stage over a wide range of variation of the dU/dt. For the CSD complete stage, the relation between the intensity of the discharge radiation in the UV region and the amplitude of the current pulse has been received. The dependence of the maximum electron concentration on the UV radiation intensity of the high-current stage CSD was obtained for the case when UV radiation from the CSD was used for ionization of atmospheric pressure nitrogen.
Energy of low-temperature synthesis of graphen-like carbon nanocomposites on porous silicon (Review)
Authors: Tynyshtykbayev K , Insepov Z
Published: December 2020

The process of low temperature synthesis of graphene-like nanocomposites films on the porous silicon nanocrystallites (nc-PS) is considered. It was shown that the low temperature synthesis of graphene-like nanocomposites on nc-PS is due to the excess surface energy of porous-Si nanocrystallites and, in this case, nanoscale effects that occur on local parts of the atomically rough nc-PS surface play a specific role. In the report features of the specific role of the atomically rough nc-PS forces and the influence these forces on the energy of low-temperature synthesis of graphene-like nanocomposites on the surface of porous silicon nanocrystallites are considered.
Numerical modelling of water hammer with cavitation
Authors: Sumskoi S I , Sverchkov A M
Published: December 2020

A new numerical method for solving a system of one-dimensional nonstationary equations describing the flow with cavitation is presented. The method is based on the Godunov approach. The method is implemented taking into account the cavitation that occurs in the flow. Test calculations have shown the acceptable accuracy of the method and its ability to describe phase transitions in the flow.
Simulation of the Intrusion Process and Extrusion of Non-Wetting Liquid From Porous Media in Quasi-Static Mode
Authors: Byrkin V A , Geraseva A V
Published: December 2020

To understand the thermodynamics, transport and physical phenomena in porous media today, the most effective way is to use various models of porous media and conduct numerical experiments on their basis. It has been shown that such models are an effective tool for research of transport processes from the local scale at the level of individual pores to the level of individual granules. The approach proposed in this paper is based on numerical calculations based on known theoretical approaches. The principal difference from the previously used approaches and novelty lies in the absence of simplifications associated with the narrowing of the distribution of pores in size and the number of nearest neighbors, which allows us to take into account in detail the possible geometric configurations, when the pore of the same radius can be surrounded by a different number of neighboring pores. In addition, the use of numerical modelling allows us to obtain a large number of different parameters, ranging from structural characteristics (the number of nearest neighbors, connectivity, etc.), cluster (percolation thresholds) and ending with volume dependencies on pressure and time and the visualization of filling processes.
Hysteresis of Percolation Transition and Relaxation of Fast and Slow States of the System Nanoporous Medium - Non-Wetting Liquid
Authors: Belogorlov A A , Borman V D , Bortnikova S A , Byrkin V A , Tronin I V , Tronin V.N.
Published: December 2020

In the present paper we present the results of experimental and theoretical studies of intrusion-extrusion and relaxation of non-wetting liquid in three Fluka porous media. New data on hysteresis of intrusion-extrusion and dependence of the degree of filling of a porous body on time in the process of extrusion were obtained experimentally. It has been established that in all the conducted experiments the liquid extrusion took place in two stages: at the first stage of fast relaxation the characteristic time of outflow is several seconds, at the second stage of slow relaxation the characteristic time is several hundred seconds. The experimental data obtained are described in the theoretical model [1]. For the studied porous media, the existence at the initial moment of time of local states with short leakage times (a few seconds or less) and states with large leakage times (hundreds of seconds) was established. Porous bodies in which the coexistence of fast and slow states at the initial moment of time is established are investigated for the first time.
Study of Constant Filling Pressure Conditions in a System “Nanoporous Medium - Non-wetting Liquid” in an Impact Process
Authors: Khlistunov I A , Belogorlov A A , Borman V D
Published: December 2020

In this work critical constant filling pressure conditions for systems “nanoporous medium - non-wetting liquid” under impact were studied. To determine the conditions influencing on the occurrence of a constant filling pressure, a series of impact experiments have been carried out on four porous media with distilled water as non-wetting liquid. On the basis of the obtained experimental data for the systems under investigation, a method for determining the flow rate of liquid in the pores was developed and its values for the systems under investigation in a given range of impact energies were determined. It is shown that the liquid flow rate in the pores is one of the key parameters determining the presence of a constant critical filling pressure. It was also found that in the investigated energy range the liquid flow rate increases and goes to limit with increasing impact energy.
Study of the model system for delivery and controlled release of anticancer drugs in affected areas.
Authors: Belogorlov A A , Bortnikova S A , Kulakov S A , Mingalev P G , Akopdzhanov A G , Shimanovskii N L
Published: December 2020

The modern clinical oncology key task is to increase the efficiency of anticancer chemical therapy. The main direction of provided investigations are to ensure targeted delivery of drugs to cancer cells with the minimization of the harmful effect to normal cells, as well as overcoming the multiple drug resistance of cancer cells. One of the possible solutions is to use nanoporous medium filled with non-wetting liquid (drug) as a carrier. Interest to such systems is caused by two effects observed for such systems: the effect of non-wetting liquid dispersion in pores and it’s anomalously slow relaxation (outflow). It has also been shown that these effects are critically dependent on temperature. The work is present results of experimental study of the kinetics of model liquid outflow from nanoporous medium at the temperature range 20-40 °C. Results obtained for systems with different granule sizes and surface modifications.
Study of sorption properties of HF 512O and NaX synthetic zeolites in the process of sorption of air mixture components
Authors: Tishin A A
Published: December 2020

The sorption properties of synthetic zeolites HF 512O and NaX were studied. In the course of the study, the volume method obtained the sorption capacities of zeolites for nitrogen and oxygen. The experimental setup for determining the sorption capacity by volumetric method consisted of two tanks. The first tank has a known volume, and the second tank is filled with the studied sorbent. Helium was used to determine the free volume of the second tank. The gas sorption capacity of which must be determined is fed to the first tank, the second tank is pumped out using a vacuum pump, after which the tanks are connected and the separation in the tanks is leveled. Thus, the sorption capacity of the sorbent can be calculated based on the pressure drop in the system. The selectivity of sorbents for the nitrogen – oxygen pair for pure gases was calculated.
Modeling and Comparison with Experiment of SAW Induced Water Droplet Motion
Authors: Zhakiyev N , Tynyshtykbayev K , Insepov Z
Published: December 2020

A water droplet motion on a piezoelectric substrate, which is actuated using Surface Acoustic Waves (SAW), is presented toward water desalination purposes. The processes of fluid flow motion under different RF powers and SAW frequencies, induced by internal streaming, has been observed both experimentally and numerically. A free droplet dynamics in the volume of 2 and 5 μl interacted with intensive SAW on the piezoelectric substrate surface for 34 and 58 MHz frequencies, and power output between 0 - 4 dBm observed. In tha paper a three-dimensional (3D) finite element model using computational fluid dynamics approach of the free water droplet motion was developed. The different dependences of microfluidic performance such as locally streaming lines, slip length and droplet motion velocity have been studied.