bluuebunny/crossref_metadata_2025 huggingface dataset:
The Use of 5-Hydroxymethylfurfural towards Fine Chemicals: Synthesis and Direct Arylation of 5-HMF-Based Oxazoles
Authors: Jacolot Maïwenn , Popowycz Florence , da Rosa Rafael , Grand Lucie , Schenkel Eloir P. , Sibelle Campos Bernardes Lílian
Published: December 2020

5-Hydroxymethylfurfural (5-HMF) is a renewable platform chemical used as a source for obtaining diverse fine chemicals. In this letter, we report the synthesis of 5-HMF-based oxazole compounds. While 5-HMF could be easily converted into the oxazole derivative through the Van Leusen reaction, the direct arylation step needed to access the final compounds was problematic at first. After optimization, a palladium-catalyzed procedure has been developed and used for the synthesis of a series of 33 derivatives. This article reports an extension of the late-stage CH arylation reaction as an application to the oxazole platform derived from biosourced 5-HMF. The challenges in the preparation of the derivatives containing some electron-withdrawing substituents were overcome by the use of a palladium-free method.
Polyanions in Coagulation and Thrombosis: Focus on Polyphosphate and Neutrophils Extracellular Traps
Authors: Rangaswamy Chandini , Englert Hanna , Deppermann Carsten , Renné Thomas
Published: December 2020

Neutrophil extracellular traps (NETs) and polyphosphates (polyP) have been recognized as procoagulant polyanions. This review summarizes the activities and regulation of the two procoagulant mediators and compares their functions. NETs are composed of DNA which like polyP is built of phosphate units linked by high-energy phosphoanhydride bonds. Both NETs and polyP form insoluble particulate surfaces composed of a DNA/histone meshwork or Ca2+-rich nanoparticles, respectively. These polyanionic molecules modulate coagulation involving an array of mechanisms and trigger thrombosis via activation of the factor XII-driven procoagulant and proinflammatory contact pathway. Here, we outline the current knowledge on NETs and polyP with respect to their procoagulant and prothrombotic nature, strategies for interference of their activities in circulation, as well as the crosstalk between these two molecules. A better understanding of the underlying, cellular mechanisms will shed light on the therapeutic potential of targeting NETs and polyP in coagulation and thrombosis.
Non-neoplastic Soft Tissue Tumors and Tumor-like Lesions
Authors: Shah Amit , Paramesparan Kethesparan , Robinson Philip , Rennie Winston J.
Published: December 2020

Clinicians are commonly faced with patients presenting with a solitary palpable soft tissue mass. Most soft tissue lesions are benign, and not every mass is due to a neoplastic process. Many pathologies can mimic a malignant tumor. Despite appropriate clinicoradiologic assessment, these lesions can be mistaken for a soft tissue sarcoma and can lead to multiple investigations or an intervention, inconveniencing patients and leading to an increased health care cost. With the relevant clinical history, clinical examination, and specific imaging characteristics, the diagnosis can be narrowed. We present a pictorial review of soft tissue sarcoma mimics with guidance on appropriate differential diagnoses.
Diagnosis, Staging, and Patient Selection for Locoregional Therapy to Treat Hepatocellular Carcinoma
Authors: Berman Zachary T. , Newton Isabel
Published: December 2020

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related mortality and the only cancer for which the incidence and mortality are on the rise. Sensitive and specific screening and diagnostic approaches, robust staging regimens, multidisciplinary tumor boards, and patient/family education and engagement in the shared decision-making process help to identify a patient's optimal treatment options. Locoregional therapies have been the mainstay for treating intermediate-stage disease, but they are finding special applications for early and advanced disease. This review discusses the diagnosis of HCC, current accepted staging models, and treatment of HCC, with a focus on locoregional therapies.
Interventional Oncology Approach to Hepatic Metastases
Authors: O'Leary Cathal , Soulen Michael C. , Shamimi-Noori Susan
Published: December 2020

Metastatic liver disease is one of the major causes of cancer-related morbidity and mortality. Locoregional therapies offered by interventional oncologists alleviate cancer-related morbidity and in some cases improve survival. Locoregional therapies are often palliative in nature but occasionally can be used with curative intent. This review will discuss important factors to consider prior to palliative and curative intent treatment of metastatic liver disease with locoregional therapy. These factors include those specific to the tumor, liver function, liver reserve, differences between treatment modalities, and patient-specific considerations.
Hepatic Metastasis from Breast Cancer
Authors: Liberchuk Ariel N. , Deipolyi Amy R.
Published: December 2020

Breast cancer is the most common cancer in women and breast cancer liver metastasis may be associated with poor outcomes. Emerging locoregional therapies can be given in outpatient settings or with short hospital stays, to provide local control, support quality of life, preserve liver function, and potentially prolong survival. This review discusses retrospective studies suggesting potential benefits of locoregional treatment of breast cancer liver metastasis. Future prospective studies are needed to demonstrate efficacy and optimize patient selection.
Treatment Options for Early-Stage Hepatocellular Carcinoma
Authors: Tabori Nora E. , Sivananthan Gajan
Published: December 2020

Patients with early stage hepatocellular carcinoma have good prognosis and are treated with curative intent. Although this cohort of patients is generally defined by limited tumor burden, good liver function, and preserved functional status, there remains utility in further stratification to optimize overall survival and limit post-operative morbidity and mortality. Transplant, resection, ablation, transarterial radioembolization, and transarterial chemoembolization, either as monotherapy or in combination, may play a crucial role in treating this cohort of patients depending on a multitude of factors. In this section, we review each treatment modality and provide general guidelines for patient selection.
Weight Cycling in Women: Adaptation or Risk?
Authors: Carey Katelyn J. , Vitek Wendy
Published: December 2020

Obesity, dieting, and weight cycling are common among reproductive-age women. Weight cycling refers to intentional weight loss followed by unintentional weight regain. Weight loss is accompanied by changes in gut peptides, adipose hormones, and energy expenditure that promote weight regain to a tightly regulated set point. While weight loss can improve body composition and surrogate markers of cardiometabolic health, it is hypothesized that the weight regain can result in an overshoot effect, resulting in excess weight gain, altered body composition, and negative effects on surrogate markers of cardiometabolic health. Numerous observational studies have examined the association of weight cycling and health outcomes. There appears to be modest association between weight cycling with type 2 diabetes mellitus and dyslipidemia in women, but no association with hypertension, cardiovascular events, and overall cancer risk. Interestingly, mild weight cycling may be associated with a decreased risk of overall and cardiovascular mortality. Little is known about the effects of weight cycling in the preconception period. Although obesity and weight gain are associated with pregnancy complications, preconception weight loss does not appear to mitigate the risk of most pregnancy complications related to obesity. Research on preconception weight cycling may provide insight into this paradox.
Evaluation of Treatment Changes in the Maxillary Intercanine and Intermolar Width in Patients with Various Malocclusions: A Study Model Analysis
Authors: Aggarwal Isha , Kharel Adarsh Deep , Mittal Sanjay , Bhullar Mandeep K. , Palkit Tanzin
Published: December 2020

Introduction Since extraction and nonextraction is a debatable topic to date, its effects on the changes in the dimension of arch width are unclear. Many investigators suggested that extraction would lead to arch collapse, whereas few others suggested that such changes in dimension would not occur.

Aim and Objectives  To evaluate the changes in the intercanine and intermolar width in premolar extraction cases in class I and class II div 1 malocclusion cases.

Materials and Methods The study included pretreatment and posttreatment study models of 25 patients (14 with class I malocclusion, 11 with class II division 1 malocclusion). Intercanine and intermolar widths were measured and evaluated for both the malocclusions. The difference posttreatment intercanine width and intermolar width between class I and class II division 1 malocclusion were also assessed. The values obtained were subjected to statistical analysis.

Results There was no statistically significant difference in the intercanine and intermolar width pre- and posttreatment for class I patients, but there was a statistically significant difference in the intercanine and intermolar widths in class II patients. When class I and class II patients were compared for the parameters (intercanine/intermolar widths), it showed that there was no statistically significant difference.
Soil biota and non-native plant invasions.
Authors: Callaway Ragan M. , Lucero Jacob E.
Published: December 2020

The trajectory of plant invasions - for better or for worse - can be tied to interactions between plants and the soil community. Here, we highlight five broad ways in which belowground interactions can influence the trajectory of biological invasions by non-native plant species. First, many non-native plant species in their non-native ranges can interact very differently with the resident soil community than do native species. Second, non-native plant species often interact very differently with the soil community in their non-native ranges than in their native ranges, which can result in enemy release from antagonistic interactions. Third, non-native plant species can cultivate a soil community that disproportionately harms native competitors in invaded communities. Fourth, antagonistic soil biota in invaded communities can reduce the performance of non-native plant species, resulting in meaningful biotic resistance against invasion. Fifth, besides or in addition to antagonistic interactions with soil biota, soil mutualisms can promote the success of invasive plant species (i) when mutualists co-invade with non-native plant species that require obligate specialist mutualists, (ii) when mutualists enhance the performance of non-native plant species in their non-native ranges, and (iii) when biotic interactions in the invaded community suppress the soil mutualists of native plant species. We conclude that management practices aimed at manipulating plant - soil interactions have considerable potential to help control plant invasions, but further work is needed to understand the spatial, temporal, taxonomic and biogeographic drivers of context dependence in interactions among plants and soil biota.
The effect of non-native plant invasions on the dispersal of native seeds.
Authors: Heleno Ruben H.
Published: December 2020

Non-native plants change the communities they integrate in multiple ways, including direct and indirect effects on co-occurring native vegetation. While direct effects are more obvious, indirect effects, i.e. those mediated by biotic interactions with other trophic levels, can also have pervasive consequences for long-term community persistence. Seed dispersal is a critical stage during the life cycle of most plants, as it lays the foundations for plant recruitment patterns and long-term vegetation dynamics. By interacting with seed-dispersing animals, primarily frugivorous birds and mammals, plants can positively or negatively affect the dispersal of co-occurring native seeds. In an increasingly invaded world, it is thus critically important to identify general trends on the direction and magnitude of these effects. This chapter reviews the empirical evidence supporting such changes and the potential underlying mechanisms driving them. While the direct impacts of plant invasions are relatively easy to document, indirect effects are much harder to detect. Nevertheless, the most important consequence of the incorporation of new fruiting plants into native communities seems to be a direct competition for the services provided by the local dispersers, negatively affecting native seed dispersal rates. However, another key message emerging from the literature is that responses are highly idiosyncratic, and usually habitat- and species-specific, and therefore resistant to broad generalizations. Fruiting phenology, and in particular the synchrony/asynchrony between the availability of native and non-native fruits, seems to be a particularly important driver of the direction of the responses (i.e. towards facilitation or competition). However, most evidence is still derived from anecdotal observations and formal community level assessments are largely missing. Similarly, how invasive plants change the emergent structure of seed dispersal networks remains uncertain, with early evidence suggesting that novel seed dispersal networks might be structurally very similar to native ones. Bringing together classic experimental designs and new technical and analytical tools to provide broad synthesis will be vital in the near future to clarify the direction, magnitude and generality of these effects.
Allelopathic disruptions of biotic interactions due to non-native plants.
Authors: Smith-Ramesh Lauren M.
Published: December 2020

Allelopathy, or the process by which plants influence the growth and performance of their neighbours through the release of chemicals, may play a key role in mediating the impacts of non-native invasive species on their neighbours. The Novel Weapons Hypothesis purports that non-native invasive species are in part successful because they produce harmful allelochemicals to which resident species are particularly susceptible because residents lack a shared evolutionary history with the invader. While allelopathic non-native invaders may reduce the growth and performance of neighbours through direct phytotoxicity, they may more often exert negative impacts through disruption of biotic interactions among resident species. Allelopathy by non-native plants may disrupt mutualisms between resident plants and microbes, plant-herbivore interactions or existing competitive and facilitative interactions among resident plants. For example, several non-native plants are known to disrupt the mutualism between resident plants and mycorrhizal fungi, reducing resident plant fitness to the benefit of the invader. Allelopathic non-natives may also disrupt interactions among resident plants and their herbivores when allelochemicals also influence herbivore behaviour or fitness. Alternatively, biotic interactions can also be protective for resident species, which may be less susceptible to the impacts of non-native species when their mutualisms are intact. As we advance our understanding of allelopathy and its role in mediating the impacts of invasive plant species, we may gain new insights by viewing invasions within a network context rather than focusing on pairwise interactions.
Restoration of seed dispersal interactions in communities invaded by non-native plants.
Authors: da Silva Fernanda Ribeiro , Pizo Marco Aurélio
Published: December 2020

Restoration aims to rebuild not only species but also the tangled interactions between species that ensure communities perpetuate by themselves. In tropical forests, restoration of seed dispersal interactions is essential because most plant species depend on animals to spread their seeds. A big challenge in restoring such forests is dealing with invasion by non-native species. Non-native plant species may outcompete and eliminate native species from the community, potentially disrupting or arresting the restoration process. Once established, invasive non-native plants are usually incorporated into the local seed dispersal network, potentially causing loss of biodiversity by competition with native species. This chapter reports on a case study of a 25-year old restored forest invaded by several bird-dispersed plant species. We assessed network metrics at the species level to specifically evaluate the role performed by invasive non-native species in the structure of the bird - seed dispersal network. The removal of invasive non-native plants and the re-establishment of native plant communities should be considered for the restoration of habitats invaded by non-native plants. For this reason, we discuss the impacts of removing such non-native plants and explore the consequences for the structure of the overall network. Because restoration areas are open systems, even after the removal of invasive non-native plant species they can return via seed dispersal. So, both the control and management of invasive non-native species would be more effective if planned with a landscape perspective. We also point out relevant management aspects to avoid the negative influence of invasive non-native plants on the seed dispersal interactions occurring between native plant and bird species in restored tropical forests.
An APEX2 proximity ligation method for mapping interactions with the nuclear lamina
Authors: Tran Joseph R. , Paulson Danielle I. , Moresco James J. , Adam Stephen A. , Yates John R. , Goldman Robert D. , Zheng Yixian
Published: December 2020

The nuclear lamina (NL) is a meshwork found beneath the inner nuclear membrane. The study of the NL is hindered by the insolubility of the meshwork and has driven the development of proximity ligation methods to identify the NL-associated/proximal proteins, RNA, and DNA. To simplify and improve temporal labeling, we fused APEX2 to the NL protein lamin-B1 to map proteins, RNA, and DNA. The identified NL-interacting/proximal RNAs show a long 3′ UTR bias, a finding consistent with an observed bias toward longer 3′ UTRs in genes deregulated in lamin-null cells. A C-rich motif was identified in these 3′ UTR. Our APEX2-based proteomics identifies a C-rich motif binding regulatory protein that exhibits altered localization in lamin-null cells. Finally, we use APEX2 to map lamina-associated domains (LADs) during the cell cycle and uncover short, H3K27me3-rich variable LADs. Thus, the APEX2-based tools presented here permit identification of proteomes, transcriptomes, and genome elements associated with or proximal to the NL.
Retraction: Supplementary comparison EURAMET.L-S25 (#1354) comparison of pocket type laser distance measuring instruments
Authors: Prieto Emilio , Pérez Mar , Ruíz Juan A , Matus Michael , Kotte Gerard
Published: December 2020

It has been brought to the attention of IOP Publishing that this Technical Supplement has been published in error and is an unintended duplication of a previously published manuscript (https://iopscience.iop.org/article/10.1088/0026-1394/54/1A/04004). As such, this Technical Supplement is being retracted by IOP Publishing Limited with the agreement of BIPM and all the authors.
Hysteresis-free MoS2 metal semiconductor field-effect transistors with van der Waals Schottky junction
Authors: Wan Da , Wang Qixia , Huang Hao , Jiang Bei , Chen Chen , Yang Zhenyu , Li Guoli , Liu Chuansheng , Liu Xingqiang , Liao Lei
Published: December 2020

Hysteresis-free and steep subthreshold swing (SS) are essential for low-power reliable electronics. Herein, MoS2 metal semiconductor field-effect transistors are fabricated with GeSe/MoS2 van der Waals Schottky junction as a local gate, in which the rectification behavior of the heterojunction offers the modulation of channel carriers. The trap-free gate interface enables the hysteresis-free characteristics of the transistors, and promises an ideal SS of 64 mV/dec at room temperature. All the devices operate with a low threshold voltage less than −1 V with desirable saturation behavior. An OR logic gate is constructed with the dual-gated MoS2 transistors by varying the back and top gate voltage. The strategy present here is promising for the design of low-power digital electronics based on 2D materials.
Stochastic models of systems for Nanotechnology: from micro to macro scale
Authors: Longo Savino , Micca Longo Gaia , Hassouni Khaled , Michau Armelle , Prasanna Swaminathan
Published: December 2020

Computer modeling technique based on the theory of stochastic processes have been used in order to provide a realistic simulation of the behavior of nanoscopic systems, related in particular to plasma reactors in microelectronic device production. Basing on decades of experience, we show here, with new results, that the universality of such methods allows the development of codes with the highest reusability and versatility, crossing the barrier of scale. At the smallest scale, the quantum calculations of the potential energy surface of hydrogen species under nano-confinement conditions display the effects due to the dimension and the symmetry of the confining potential well. At a slightly larger scale, nanoparticles dispersed as aerosol in plasma feature strong fluctuations in temperature and charge which may affect the processing of silicon wafers. At the macroscopic scale, using a stochastic solution of transport equations, it is possible to describe laboratory or industrial systems for the production or treatment of nanomaterials, also exploiting the analogy between neutral particle transport and radiative transfer and information obtained by molecular simulations. These findings are relevant in the control of solid-particle contamination in the manufacture of electronic components and in other fields.
Ginzburg Landau equation's Innovative Solution (GLEIS)
Authors: Achab Abdelfattah EL , Rezazadeh Hadi , Baleanu Dumitru , Desta Leta Temesgen , Javeed Shumaila , Alimgeer Khurram Saleem
Published: December 2020

A novel soliton solution of the famous 2D Ginzburg-Landau equation is obtained. A powerful Sine-Gordon expansion method is used for acquiring soliton solutions 2D Ginzburg-Landau equation. These solutions are obtained with the help of contemporary software (Maple) that allows computation of equations within the symbolic format. Some new solutions are depicted in the forms of figures. The Sine-Gordon method is applicable for solving various non-linear complex models such as, Quantum mechanics, plasma physics and biological science.
Unsupervised fNIRS feature extraction with CAE and ESN autoencoder for driver cognitive load classification
Authors: Liu Ruixue , Reimer Bryan , Song Siyang , Mehler Bruce , Solovey Erin
Published: December 2020

Objective. Understanding the cognitive load of drivers is crucial for road safety. Brain sensing has the potential to provide an objective measure of driver cognitive load. We aim to develop an advanced machine learning framework for classifying driver cognitive load using functional near-infrared spectroscopy (fNIRS). Approach. We conducted a study using fNIRS in a driving simulator with the N-back task used as a secondary task to impart structured cognitive load on drivers. To classify different driver cognitive load levels, we examined the application of convolutional autoencoder (CAE) and Echo State Network (ESN) autoencoder for extracting features from fNIRS. Main results. By using CAE, the accuracies for classifying two and four levels of driver cognitive load with the 30 s window were 73.25% and 47.21%, respectively. The proposed ESN autoencoder achieved state-of-art classification results for group-level models without window selection, with accuracies of 80.61% and 52.45% for classifying two and four levels of driver cognitive load. Significance. This work builds a foundation for using fNIRS to measure driver cognitive load in real-world applications. Also, the results suggest that the proposed ESN autoencoder can effectively extract temporal information from fNIRS data and can be useful for other fNIRS data classification tasks.
Liquid metal flat jet transformation under influence of transverse magnetic field
Authors: Pyatnitskaya N , Luchinkin N , Belyaev I , Kolesnikov Yu , Krasnov D , Listratov Ya , Zikanov O , Sviridov E
Published: December 2020

The article is devoted to an experimental study of a submerged flat jet flow in a transverse magnetic field. Two different approaches to the experimental study of jet flows are described. Detailed information about the experimental program and measuring methods presented here. The flow of a flat jet 6 mm high in a square channel with a side of 56 mm is considered. The channel is positioned so that the plane of the jet is perpendicular to the magnetic field induction. The results of measuring velocity profiles and waveforms by swivel-type probe with potential sensor are presented. Effects that can be interpreted in different ways are found: strongly unstationary flow regimes, mean flow reorganization, and development of near-wall jets. Additional experiments are prepared to obtain more detailed information about the restructuring and development of the jet. In particular, continuous measurements along the channel will be made in the presence of a slight main flow.
Accounting for Uranium-234 During the Analysis of Experiments at the Research Fast Reactor with High Enrichment
Authors: Kotov Ya A , Nevinitsa V A , Smirnov A Yu
Published: December 2020

Paper is an attempt to consider the influence of U-234 presence through the comparison of the calculated assessments of the temperature reactivity effect (TRE) and the sodium void reactivity effect (SVRE) of the fast research reactor CEFR with 64.4% enrichment on U-235 isotope and measured values of the temperature reactivity effect and sodium void reactivity effect. Additional investigation was performed to account for U-234 in the first criticality experiment. Experimental data are provided in frames of IAEA Coordinated Research Project “Neutronics Benchmark of CEFR Start-Up Tests”. The content of U-234 was calculated by us using mathematical model of the quasi-ideal enrichment cascade. Due to the high enrichment, the content of U-234, although still small, has ceased to be vanishingly small. The effect caused by this isotope is appeared not only through the presence of new isotope in the fuel load, but also in a decrease in the mass of the U-238 isotope in the fuel load. It is shown, that accounting for U-234 slightly increases the agreement of the calculated assessments of TRE among themselves (values of deviation shifted toward each other)/Also accounting for the U-234 isotope leads to a small but systematic increase in the values of the effective multiplication factor by 120-150 pcm.
Analysis of beyond design basis accident with hydrogen explosion in the at-reactor spent fuel storage pool of NPP with RBMK-1000
Authors: Gryazev A S , Osipov A M , Finoshkina D V , Tupotilov I A
Published: December 2020

The article evaluates the consequences of a hydrogen explosion in an at-reactor spent fuel storage pool due to the development of a beyond design basis accident with a complete long-term blackout. Two scenarios of hydrogen generation in a spent fuel storage pool with a subsequent hydrogen explosion are considered. In the first scenario, the formation of radiolytic hydrogen occurs in the undried storage pool. In the second scenario, hydrogen is formed as a result of the steam-zirconium reaction in the dried storage pool when the cooling water is supplied to the walls of the emergency storage pool. The maximum explosion pressure is calculated using the shock Hugoniot adiabat. The calculations of initial static load taking into consideration hydrogen explosion exposure for each scenario were performed using the equivalent static load method. This method consists in the switch from a dynamic task to a static one, in which the maximum deflections are equivalent. The calculation of the stress-strain state of spatial structures is carried out in the ZENIT-95 program. It is shown in the work that not in all cases of hydrogen explosion, destruction of structures occurs.
New finite element neutron kinetics coupled code system FENNECS/ATHLET for safety assessment of (very) Small and Micro Reactors
Authors: Bousquet J , Seubert A , Henry R
Published: December 2020

Cores of (very) small and medium size reactor–(v)SMR – are often characterized by irregular geometries. Monte Carlo methods are not yet mature enough for transient applications. To perform coupled transient safety assessments of (v)SMRs, the Finite ElemeNt NEutroniCS (FENNECS) code is being developed at GRS. It solves the time-dependent and steady-state three-dimensional few-group diffusion equation in Galerkin finite element representation using upright triangular prisms with linear basis functions as spatial elements. FENNECS is also coupled with the GRS thermal-hydraulic system code ATHLET. For the special meshing, an external meshing tool is being developed as a Python software module. This paper considers the Heat Pipe Micro Reactor core. For the generation of cross sections to be used in FENNECS, Monte Carlo Serpent models are developed for two configurations: all absorber faces of control drums are turned out of the core (All Rods Out – ARO – configuration) and all absorber faces are turned in (All Rods In – ARI – configuration). The Serpent multiplication factors are in good agreement with the benchmark. In the FENNECS model, control drums are approximated by a 12-edges polygon or by a 24-edges polygon. The FENNECS multiplication factors agree well with Serpent reference results for both configurations. This demonstrates the applicability of FENNECS to (v)SMRs.
Radioactive waste management in PWR technology: some technical solutions for liquid radioactive media processing systems of the “nuclear island”
Authors: Vinnitskii V A , Chugunov A S
Published: December 2020

The present research is aimed at solving an urgent practical problem – to minimize the volume of the radioactive waste from nuclear power plants in the place of their generation. The modernization of the complexes for handling water streams containing radionuclides seems to be the most acceptable solution. The systems developed in the 1960s for the chemical support of the safe operation of the reactor plant and the radioactively contaminated water processing no longer meet the established requirements, primarily in terms of the volume and quality of radioactive waste subject to “eternal” isolation. The search for a reasonable compromise between the amount of waste generated during the operation of systems to ensure the safe operation of nuclear power plants and the theoretically achievable volume of radioactive waste can be considered as the current agenda. The ratio between these indicators will shift as the material and technical base of the available materials and devices is steadily improving, the base itself has significantly expanded over the past time. In this regard, the most urgent is the change in methodological approaches to the organization of chemical technological systems of NPP. First of all, this refers to the advisability of abandoning universal systems in favor of specialized ones adapted to the chemical composition of the processed “raw material”. Separate collection of liquid radioactive waters basing on the principle of chemical composition similarity will allow to use low productivity systems. In this case, local systems can be used only once. The article presents some approaches to the organization of systems capable of providing a radical reduction in the intake of ballast salts in the composition of radioactive waste.
Possibilities and Features of REMIX Technology as an Initial Stage in the Establishing of a Full-Scale Two-Component Nuclear Energy System
Authors: Sitdikov E R , Vasilenko A V , Diachenko A I
Published: December 2020

According to the Energy Strategy of Russia for the period up to 2035, the direction of the transition of the nuclear industry is to be headed to a two-component nuclear energy system (NES. In this paper, in order to identify the features of recycling MOX and REMIX fuel and to analyze possible strategies for two-component NES, the changes in the isotopic composition of the plutonium fraction during multiple recycling of fuel has been evaluated, and the consumption of plutonium in various strategies of establishing a two-component NES has been quantitatively assessed. The data obtained can be used for the further analysis of the possibility of developing the two-component NES concept with the involvement of REMIX fuel in the nuclear fuel cycle of thermal reactors at the initial stage of the establishing of a full-scale two-component NES.
Hand-foot monitors for nuclear plants based on scintillator–WLS–SiPM technology
Authors: Buzhan P , Karakash A
Published: December 2020

The technology of charged particles detection by a plastic scintillator light from which is collected by wavelength shifting fiber (WLS) on Silicon Photomultiplier (SiPM) is widely used in high energy physics. We present in this article the new personnel surface contamination monitoring assembly based on that technology as a result of about two years R&D research. This assembly is used for contamination control of hands, feet and clothes at nuclear power plants, nuclear facilities and other objects that work with radioactive materials. Setup design, main parameters and its measurement procedures are presented. It has high efficiency to α and β particles in wide energy range, large dynamic range, very good area uniformity and excellent temperature stability. Dynamic range of measured particle fluence rate equals: 1 – 106 Hz·cm2·min for β-module and 0.1 – 2·104 Hz·cm2·min for α-module. Variations of the module response in temperature range from –20 C up to +50 C doesn`t exceed 3%.
Computer technologies in the system of training specialists for the nuclear industry at ISPU
Authors: Gorbunov V A , Ilchenko A I , Andrianov S G , Mechtaeva M N , Volman M A
Published: December 2020

The article discusses the experience of effective application of computer technologies, trainers and simulators in the system of training specialists for the nuclear industry at ISPU. The necessity and relevance of using computer-based learning tools in the educational process is determined. The main stages of training specialists and the concept of multi-level training based on the wide use of computer technologies developed at ISPU are considered. The main advantages and features of using automated training systems, local computer simulators, functional analytical simulator, full-scale simulator, simulation tools, simulator of the basic principles of NPP operation, as well as packages of numerical and analytical methods of mathematical modeling in the educational process are shown. The directions for further improvement of the educational process at ISPU in order to increase the level of training of young personnel for the nuclear industry are shown.
The Modeling of kinetic characteristics of subcritical assembly “Yalina” using SuperMC Monte Carlo code
Authors: Zubets I A , Korbut T N , Kravchenko M O
Published: December 2020

Accelerator-driven systems (ADS) are considered to be promising for energy generation and transmutation of the long-live radiotoxic nuclides contained in spent nuclear fuel. The Yalina assembly has the same conceptual construction with a neutron generator coupled to a subcritical core. The major difference between ADS and Yalina experiments is that the neutron energy spectrum of the Yalina core is thermal. The simulation of the Yalina-Thermal experimental program was conducted via new neutron-physics code SuperMC developed by the FDS Team in China. SuperMC is a CAD-based Monte Carlo program for integrated simulation of nuclear systems by making use of hybrid Monte Carlo and deterministic methods and advanced computer technologies. The calculations were held with the use of the up to date nuclear data libraries ENDF/B-VII.1, ENDF/B-VIII, FENDL 3.0, JEFF 3.3, JENDL 4.0. The effective multiplication constant, keff, and the fraction of delayed neutrons, βeff, were calculated for the 285 fuel rod core configuration of the Yalina-Thermal subcritical assembly. Evaluation of the Yalina-Thermal experimental program using SuperMC code has been made for the first time in this work.
Estimation of pressure during steam explosion in the sub-reactor room of NPP with RBMK-1000
Authors: Finoshkina D V , Melikhov O I , Osipov A M
Published: December 2020

The article analyzes the scenario of a severe beyond the design basis accident with core melting at a nuclear power plant with RBMK-1000. Molten reactor core falls into the sub-reactor space filled with a steam-water mixture. The interaction of melt core and the coolant can lead to the creation of conditions for the occurrence of a steam explosion. Parameters of this steam explosion have been evaluated by Hugoniot adiabat method. Such approach considers the steam explosion as detonation phenomenon, where shock wave impacts initial multiphase mixture and initiates melt droplets fragmentation and high heat flux from melt to water. Mass, momentum and energy conservation equations for initial mixture and for equilibrium explosion products mixture lead to Hugoniot equation for the adiabat. The tangent from initial point (initial mixture) on the plane “mixture volume-mixture pressure” to the Hugoniot adiabat determines Chapman – Jouguet point, which characterizes steam explosion parameters. Our calculations have demonstrated that obtained values of steam explosions do not exceeds dangerous limits.
Estimation of the influence of elastic neutron scattering anisotropy on the integral parameters of the model experiment
Authors: Zhukov V D , Listov A S , Pronyaev V G , Sinitsa V V
Published: December 2020

For the vast majority of isotopes presented in modern evaluated data libraries, the quality of description of elastic neutron scattering anisotropy is difficult to assess due to the lack of critical experiments that are sensitive to these data. This results in a large variation in these data, due to both the difference in the models used in the estimation, and the smoothing of the resonance peculiarities in representation of the energy dependence in the evaluated data files. This work estimates the effect of anisotropy of elastically scattered neutrons based on the model of a critical assembly with a reflector from the tested isotope. Direct estimates of the angular distributions in the evaluated data libraries were compared with the angular distributions, which were reconstructed from the resonance parameters by using Blatt-Biedenharn formula. The thickness of the reflector at which an assembly model became critical is used as a comparison value. The obtained integral characteristics of the elastic scattering anisotropy data, together with the performed comparisons of the detailed dependences of the angular distribution parameters, can serve as a basis for setting tasks to improve the quality of the evaluated data.
The analysis of RBMK neutron flux profile distortions using operational data history
Authors: Zagrebayev A M , Trifonenkov A V
Published: December 2020

In this research the operational data history was analysed. The data set given represents RBMK-1000 parameters for one month of the reactor operation. Axial flux sensors data and channel power data taken from database were considered. The transients of axial and radial-azimuthal neutron flux distributions were visualized. For the flux distribution data from 72 core channels with axial flux sensors the axial offset transients were obtained. In the operational data considered xenon-induced power oscillations were revealed. Phase and amplitude transients of the oscillations were calculated. The dynamics of phase and amplitude were visualized over the reactor core cross-sections. The values of quantities were displayed with different color shades. The iodine-135 and xenon-135 concentrations recovery problem solution was considered. Formulas for concentrations recovery were derived. The recovery procedure obtained is based on Cauchy problem solution calculation process. The dependence of accuracy of the recovered transients on the amount of the available operational data was studied. The dependency graph of calculation error on the amount of operational data was plot. The recovery of xenon-135 concentration was carried out based on the operational data history of the power unit where the phenomenon of xenon-induced power oscillations was observed.
Neutron-physical characteristics modeling of light water reactors critical corium slurry in water
Authors: Ternovykh M Y , Abdumalikov H M , Ryzhov S N
Published: December 2020

In this paper, the idea of modifying the benchmark by increasing effective multiplication factor value in the considered system without increasing the number of particles under consideration and fuel enrichment is discussed. The technology of data transmission, processing and comparison of the results of neutron-physical calculations using three modern codes developed in different countries and implementing the Monte Carlo method has been worked out. For the corium and water mixture parameters search, the method conventionally called the gradient descent method is used. The search method for areas of critical state corium slurry in water is described. This method can be used to justify nuclear safety in the corium extraction and transportation processes. The methodology is based on the combined use of 1-D and 3-D criticality calculations capabilities of the SCALE 6.2 program pack. Fall of corium particles in water simulation benchmark version is formulated. The possibility of using the algorithm to find the parameters of a corium and water mixture is demonstrated. This benchmark includes the critical state of corium slurry in water and assumes the use of regular structures in the formation of geometric models. The proposed version of the critical benchmark for the corium particles in water state contains 55% fuel.
Experience of long-term U–Al fuel performance in research reactors with low energy generation
Authors: Alferov V P , Geraskin N I , Kozhin A F , Kruglikov A E , Ozherelev S A , Serebryakov A A , Shchurovskaya M V , Yakovlev L I , Aleeva T B , Andreev D V , Gaiduchenko A B
Published: December 2020

Life cycle extension practices for U–Al fuel in Al cladding used at the OR and the IRT MEPhI research reactors are discussed. The IRT MEPhI reactor uses tube type IRT-3M FA with dispersed UO2–Al fuel meat and SAV–1 aluminum alloy as cladding. The OR reactor uses pin type fuel elements with U–Al alloy fuel meat in cladding of Al alloy AMSN. The necessity of life cycle extension for the fuel elements is caused by a large calendar time of fuel assembly operation (10–30 years) and regulatory bodies concerns about this issue. The results of fuel cladding corrosion effects estimation using available empirical correlations for the corrosion rate and the rate of oxide film growth are presented. The results of visual inspection of the fuel elements are shown. Water chemistry monitoring practises in the reactor pool and in spent fuel storage are analysed. The successful experience of the IRT MEPhI (in 2003–2007) on repeated operation of the fuel assemblies previously discharged from the core (after the storage over 5–21 years) is presented.
Test task for transmutation of 241Am in molten salt reactors
Authors: Ashraf O , Tikhomirov G V
Published: December 2020

Molten Salt Reactor (MSR) is one of the six innovative systems, which has been selected by the international Generation IV forum as a candidate for the next-generation reactors. In this paper, the transmutation of241Am, the main contributor to the waste toxicity in the nuclear fuel cycle, in both thermal- and fast-spectrum molten salt reactors is compared. The Am-cylinder is irradiated in the center of the thermal (SD-TMSR) and fast (SMSFR) spectrum MSRs, respectively, and during a long period of time. The total neutron fluxes in SD-TMSR and SMSFR are 4.1×1014 and 1.8×1015 n.cm-2.s-1, respectively. The overall change in actinides and fission products (FPs) mass during the irradiation has been investigated using direct Serpent2 calculations. Under fast spectrum irradiation, transmutation leads to produce short-lived FPs (by fission) rather than the accumulation of heavier actinides. The ratio between the maximum and initial released energy from all isotopes in the Am-cylinder has been calculated in this paper.
Water exchange amount reduction algorithm for power control of VVER-1200 reactor operating in load-following mode
Authors: Djaroum B , Solovyov D A , Semyonov A A , Vigovskiy S B , Schukin N V , Al-Shamayleh A I , Tanash H A , Molev I A
Published: December 2020

In order to solve the problem of water exchange minimization in the primary loop of VVER-1200 reactor operating in load-following mode, we chose the dynamic programming method (DPM). However, this method is very expensive in terms of RAM and computing time. A heuristic is introduced for the DPM to decrease the computational costs. The introduction of the heuristics makes it possible to cut the inefficient branches of the DPM algorithm and to increase its speed without loss of precision. In the proposed algorithm, the use of temperature regulation control reduces the amount of coolant removed from the reactor primary loop, the movement of control rods is limited, which keeps the current axial offset (AO) in the recommended area, makes it possible to equalize the energy release in the reactor core volume. The simulation results obtained confirm the improvement of reactor power control in terms of load following: deviation of core power from the load schedule is reduced, water exchange is decreased by more than 50%, which is useful from the point of view of liquid waste management and treatment.
The problem of large-scale production of plutonium-238 for autonomous energy sources
Authors: Shmelev A N , Geraskin N I , Kulikov G G , Kulikov E G , Apse V A , Glebov V B
Published: December 2020

The article is devoted to the urgent problem of large-scale production of plutonium-238. Various starting isotopes and Pu-238 production schemes are analyzed. The isotope characteristics of the chain based on the starting Np-237 isotope are presented. It has been substantiated that the region of neutron resonant absorption for the isotope Np-237 is the preferred spectrum of its irradiation. It is proposed to form a region with a preferred neutron spectrum in the fast reactor core for irradiation of neptunium-237. The preferred spectrum is achieved by a heterogeneous target structure including neptunium-237 and a moderator with a high atomic weight (Pb, Pb-208, Bi, Pb-Bi eutectic). It is shown that when a moderator with a high atomic weight is used, it becomes possible to form an extensive region with the preferred spectrum. In conclusion, the main conditions for the large-scale production of isotopically pure Pu-238 in a fast reactor are formulated.