Fusion Science and Technology最新文献

{"title":"Modeling the Tokamak Exhaust Processing System in a Commercial Simulator for Process Monitoring Purposes","authors":"Eduardo Iraola, José M. Nougués, Lluís Batet, Josep A. Feliu, Luis Sedano","doi":"10.1080/15361055.2023.2260238","DOIUrl":"https://doi.org/10.1080/15361055.2023.2260238","url":null,"abstract":"AbstractNuclear fusion depends on tritium breeding and self-sufficiency. Tritium represents a hazard due to its radioactivity and migration properties. Because of these difficulties, ITER, the largest fusion experiment so far, relies on a conservative static procedure to monitor the tritium inventory. Future commercial fusion plants can avoid operation halts if a dynamic monitoring strategy proves itself valid. Tritium plant models have been developed for this kind of monitoring and analysis task, but sensor accuracy and reliability are an issue still to be addressed, and the path to dynamic monitoring remains unclear. The present work shows the modeling procedure of the Tokamak Exhaust Processing system in a commercial simulator, Aspen HYSYS, to reproduce the inventories, streams, process conditions, and compositions of this subsystem during operation. The model is verified in a steady-state scenario using data from the available literature. A demonstration of such a tritium plant subsystem shows meaningful value for several reasons. First, this process has not been modeled before in commercial dynamic simulators, which are typically used in the process industry. It will also allow new stakeholders to participate in future fusion-related projects. Second, it will play a key role in industry-like tritium process monitoring, in which the new model will act as a digital twin of the plant. Data-driven diagnostics can be fueled by model data, helping engineers to generate additional data that could otherwise be expensive to get directly from the plant. For these reasons, models will represent an essential part of a dynamic monitoring system, necessary for feasible fusion projects.Keywords: Tritium processingtokamak exhaust processingdynamic modelingAspen HYSYSisotopic database AcronymsADS:=Atmosphere Detritiation SystemANS:=Analytical SystemDF:=Decontamination FactorDS:=Detritiation SystemGDC:=Glow Discharge CleaningISS:=Isotope Separation SystemNBI:=Neutral Beam InjectorPERMCAT:=PERMeator CATalytic reactorPI:=proportional-integralSDS:=Storage and Delivery SystemSRK:=Soave-Redlich-KwongTEP:=Tokamak Exhaust ProcessingTLK:=Tritium Laboratory KarlsruheVDS:=Vent Detritiation SystemWDS:=Water Detritiation SystemDisclosure StatementNo potential conflict of interest was reported by the author(s).Notesa DF is defined for the TEP system as the ratio between input tritium flow rate to output tritium flow rate.[Citation10]Additional informationFundingThis work has been possible thanks to co-funding of the Centro para el Desarrollo Tecnológico Industrial of the Spanish Ministry of Science and Innovation [IDI-20200750] and to the Industrial Doctorates Plan of the Government of Catalonia [2018 DI 0048].","PeriodicalId":12626,"journal":{"name":"Fusion Science and Technology","volume":"28 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135265668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microdispersed Ti/B/N Materials Synthesized in Chain Reactions in Processes Initiated by Microwaves of a High-Power Gyrotron: Structure and Cytotoxicity","authors":"Nina N. Skvortsova, Ekaterina A. Obraztsova, Vladimir D. Stepakhin, Evgeny M. Konchekov, Tatiana E. Gayanova, Lilja A. Vasilieva, Dmitrii A. Lukianov, Andrey V. Sybachin, Dmitry A. Skvortsov, Namik G. Gusein-Zade, Oleg N. Shishilov","doi":"10.1080/15361055.2023.2255442","DOIUrl":"https://doi.org/10.1080/15361055.2023.2255442","url":null,"abstract":"AbstractAn original plasma-chemical facility has been developed at the Prokhorov General Physics Institute of the Russian Academy of Sciences based on the gyrotrons of the thermonuclear complex of the L-2 M/MIG-3 stellarator. The scope of its applications includes the synthesis of powders for new types of catalysts, the formation and doping of ceramics, and other applications. We have previously demonstrated that in specific conditions, chain oscillatory reactions can be initialized in the reactor by powerful microwave pulses of the gyrotron in mixtures of metal and dielectric powders, resulting in the formation of microdispersed materials with controllable physical and chemical properties.In such reactions, initiated in mixtures of Ti and B, BN powders in a series of particle samples with a developed surface have been obtained. The resulting materials have a heterogeneous composition and size distribution controlled by the synthesis conditions. Thus, the obtained structures exhibit repeatable characteristics attractive for numerous applications, from catalytic particle formation and reinforcement additives to biomedical materials. In order to analyze the hazardless of the materials, cytotoxicity tests were necessary.In this work, the methods for such an analysis have been applied. The study of the obtained samples for cytotoxicity against human cells (lines HEK293T, MCF7, A549, VA13) showed toxic effects only at concentrations of tens of mg/L and the absence of detectable toxic effects in bacterial system (E. coli). The low toxicity at the cellular level indicates the potential for the safe use of the proposed microstructures, but requires further testing of safety at the organism level.Keywords: Plasma-chemical synthesisgyrotron irradiationnanostructuresnano dispersed powderscytotoxicity AcknowledgmentsThis work was carried out within the framework of the State Assignment GZ BV10-2023, “Study of innovative synthesis of micro- and nanoparticles with controlled composition and structure based on a microwave discharge in gyrotron radiation.”Disclosure StatementNo potential conflict of interest was reported by the authors.Supplementary MaterialsSupplemental data for this article can be accessed online at https://doi.org/10.1080/15361055.2023.2255442Additional informationFundingThis work was supported by the Ministry of Science and Higher Education of the Russian Federation (GZ BV10–2023), Lomonosov Moscow State University.","PeriodicalId":12626,"journal":{"name":"Fusion Science and Technology","volume":"51 5","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135367226","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Possibilities of Reprocessing Solid Waste with Tritium from Fusion Using High-Temperature Heating","authors":"Jaroslav Stoklasa, Jan Hrbek, Lucie Karásková Nenadálová, Bence Mészáros, Mykhaylo Paukov","doi":"10.1080/15361055.2023.2259227","DOIUrl":"https://doi.org/10.1080/15361055.2023.2259227","url":null,"abstract":"This study evaluates the types of waste generated by tritium during nuclear fusion. Some methods of reprocessing and decontaminating solid waste using thermal processes are evaluated, and the advantages and disadvantages of different methods are compared. The high-temperature technology selected for this study is intended for use in the EU DEMO project in the area where waste from nuclear fusion reactions is processed. Safety and environmental concerns around the technology are evaluated. The potential for detritiation of solid wastes of various sizes are investigated. The study’s focus is on wastes comprising mostly tungsten dust grains of various sizes. The possibilities and rationale for the use of high-temperature technologies are investigated. Tests conducted focus primarily on tungsten waste in powder form in various atmospheres. Problems related to the induction heating and melting of metals and nonmetals are addressed.","PeriodicalId":12626,"journal":{"name":"Fusion Science and Technology","volume":"51 12","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135366798","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermal Effects on Dynamic Behavior of CFETR Vacuum Vessel","authors":"Songbo Han, Xiaojun Ni, Jian Ge, Jinxin Sun","doi":"10.1080/15361055.2023.2259749","DOIUrl":"https://doi.org/10.1080/15361055.2023.2259749","url":null,"abstract":"AbstractThe vacuum vessel (VV) of the China Fusion Engineering Test Reactor (CFETR) was designed to withstand the variable structural loads resulting from dynamic excitation, such as seismic and plasma disruption. Modal analysis, a powerful tool, was used to evaluate the structural dynamic characteristics, such as frequency and mode shape. In addition, the CFETR VV has three different temperature conditions: room temperature (20°C), normal operation temperature (100°C), and baking temperature (200°C).In this paper, in order to investigate the influence of such different temperature conditions to the dynamic behavior of the VV, three independent finite element analysis with the same modal analysis method were performed. According to analysis results, there are obvious thermal effects on the dynamic behavior, such as nature frequency and mode shape, among the different temperature cases for the CFETR VV. Moreover, the results show that the natural frequency for each order decreases as the temperature increases, and the mode shape of the VV also changed with temperature.Keywords: CFETRvacuum vesselfinite elementmodal analysisthermal effect AcknowledgmentsThe authors are grateful to those who have given helpful advice. We would like to express our gratitude to the referees for information and suggestions that helped the quality of this paper significantly.Disclosure StatementNo potential conflict of interest was reported by the authors.Additional informationFundingThe research is supported by the National Key R&D Program of China (2017YFE0300500).","PeriodicalId":12626,"journal":{"name":"Fusion Science and Technology","volume":"31 7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135854814","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Parameter Space Constraints for Compact Spherical Tokamak Fusion Reactors","authors":"P. N. Maya, S. P. Deshpande","doi":"10.1080/15361055.2023.2247854","DOIUrl":"https://doi.org/10.1080/15361055.2023.2247854","url":null,"abstract":"AbstractParameter space for spherical tokamak reactors is explored quantitatively to elucidate the main constraints for spherical tokamak design choices. Using a constant plasma current Ip search constraint, a set of four Ip scenarios (5, 10, 15, and 20 MA) is first explored in a wide parameter space. Considering modest but gradually increasing auxiliary power, a set of four machine configurations (major radius R = 1.25, 1.75, 2.25, and 3.5 m) is explored next, optimizing the Ip and the bootstrap fraction. Constraints that narrow down the vast parameter space are elaborated along with critical assumptions, such as current drive efficiency, H-mode enhancement factor, nuclear shielding efficiency, and confinement scaling. Limits on the current density of the center post and how it affects the shielding are quantitatively indicated, thereby setting a lower limit on the aspect ratio.Keywords: Fusion power plantspherical tokamakreactor designsystems codescoping studies AcknowledgmentsThe authors would like to acknowledge the help rendered during the preparation of the manuscript by Research Scholar Piyush Prajapati. We also thank the IPR HPC (ANTYA) team for their help. The authors also would like to acknowledge the anonymous reviewers for their valuable suggestions for improving the quality of the paper.Disclosure StatementNo potential conflict of interest was reported by the authors.","PeriodicalId":12626,"journal":{"name":"Fusion Science and Technology","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135094046","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Foreword: Special issue featuring papers from the 25th Topical Meeting on the Technology of Fusion Energy (TOFE 2022)","authors":"Arkady Serikov","doi":"10.1080/15361055.2023.2254619","DOIUrl":"https://doi.org/10.1080/15361055.2023.2254619","url":null,"abstract":"We are delighted to bring you this Fusion Science and Technology (FST) special issue featuring papers derived from the 25th Technology of Fusion Energy topical meeting (TOFE 2022). TOFE 2022 was organized as an embedded topical in the American Nuclear Society Annual Meeting and conducted June 12–16, 2022, with in-person attendance in Anaheim, California, at the Anaheim Hilton. The FST editors appreciate the tireless efforts of the TOFE 2022 organizers to manage all the intricate conference processes. The dedication and commitment of the conference general chair (Dr. Ales Necas) and technical program chair (Dr. Paul Humrickhouse) contributed to a smooth and enjoyable experience for the conference attendees. TOFE 2022 attracted worldwide specialists in fusion technology whose efforts may make possible, in the not-too-distant future, the harnessing of energy from thermonuclear reactions. Meeting highlights included the executive plenary session moderated by Dr. Scott Hsu, the U.S. Department of Energy (DOE) lead fusion coordinator. Above all, the TOFE 2022 participants experienced joyful face-to-face communications and networking, which were sorely missed, as the previous TOFE was held online only in 2020 because of the COVID-19 pandemic. Attendees were happy to connect with other professionals in the field and learn about the latest advancements and research in fusion technology. This special issue of FST presents 27 peer-reviewed articles including 24 research articles and 3 student papers showcasing cutting-edge fusion technology. The issue’s contents span the breadth of the topics at TOFE 2022 across five subjects: 1. Neutronics of fusion devices with assessment of their safety and environmental impacts.","PeriodicalId":12626,"journal":{"name":"Fusion Science and Technology","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135482032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interaction of the Substance of the Tsarev Meteorite with Radiation from a Powerful Gyrotron: Dusty Plasma Cloud Formation and Phase Transformations","authors":"Nailya S. Akhmadullina, Valentin D. Borzosekov, Nina N. Skvortsova, Vladimir D. Stepakhin, Namik G. Gusein-Zade, Dmitriy V. Malakhov, Alexander V. Knyazev, Tatiana E. Gayanova, Anastasiya K. Kozak, Alexander S. Sokolov, Karen A. Sarksyan, Aleksey V. Ishchenko, Ilya A. Weinstein, Victor I. Grokhovsky, Oleg N. Shishilov","doi":"10.1080/15361055.2023.2250669","DOIUrl":"https://doi.org/10.1080/15361055.2023.2250669","url":null,"abstract":"AbstractA new approach for simulation of the interaction of space and lunar dust with the surface of spacecrafts has been proposed. The approach is based on creating a dusty plasma cloud when the substance imitating the space or lunar dust is treated with high-power pulsed microwave radiation in the developed experimental facility. The facility consists of a high-power gyrotron (75 GHz, 0.8 MW); a plasma-chemical reactor; and a diagnostic complex, which includes optical emission spectrometers and a high-speed camera. The approach has been tested using the substance of the Tsarev meteorite, which represents a typical substance of meteorites. It was found that the substance mainly keeps the phase composition; however, the particles change their morphology due to rapid heating and melting.Keywords: Plasmaspace dustlunar dustsimulationmicrowave Disclosure StatementNo potential conflict of interest was reported by the author(s).Supplementary MaterialSupplemental data for this article can be accessed online at https://doi.org/10.1080/15361055.2023.2250669.Additional informationFundingThis work is supported by the Ministry of Science and Higher Education of the Russian Federation, project FEUZ-2023-0014.","PeriodicalId":12626,"journal":{"name":"Fusion Science and Technology","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135060509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Auto-Recording System for Long-Pulse Negative Ion–Based Neutral Beam Injection Experimental Data","authors":"Y. Li, C. D. Hu, Y. Z. Zhao, S. H. Song, Y. H. Xie, Y. Gu, Z. Wang, T. Ban, Q. L. Cui","doi":"10.1080/15361055.2023.2240184","DOIUrl":"https://doi.org/10.1080/15361055.2023.2240184","url":null,"abstract":"AbstractFor long-pulse negative ion–based neutral beam injection (NNBI) experiments, an automatic recording system was designed. The data processing algorithm of neutral beam injection was implemented on the basis of existing methods, and different experimental data were processed in a mode-based method according to the physical characteristics of the neutral beam injection experiment. Based on MDSplus segment storage technology, the range of recorded data was determined by intercepting the segment sequence number of the time series data. LabVIEW was used to achieve the efficient and accurate transmission of experimental processing data. A set of tests demonstrates that the NNBI auto-recording system meets the requirements of the NNBI experience in data processing accuracy (normalized mean square error [NMSE] < 0.04), data transmission accuracy (>98%), and data affect presentation. This system not only obviously improves the work efficiency, but also provides more reliable data sources for the intelligent analysis and processing of the NNBI system.Keywords: NNBIion sourceMDSplusdata processing Disclosure StatementNo potential conflict of interest was reported by the authors.Additional informationFundingThis work was supported by the National Key R&D Program of China (no. 2017YFE300101), the National Natural Science Foundation of China (no. 11975261), and the Comprehensive Research Facility for Fusion Technology Program of China (no. 2018-000052-73-01-001228).","PeriodicalId":12626,"journal":{"name":"Fusion Science and Technology","volume":"96 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135059309","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ViMA – The Spinning Rotor Gauge to Measure the Viscosity of Tritium Between 77 and 300 K","authors":"Johanna Wydra, Alexander Marsteller, Robin Größle, Florian Priester, Michael Sturm","doi":"10.1080/15361055.2023.2238170","DOIUrl":"https://doi.org/10.1080/15361055.2023.2238170","url":null,"abstract":"Experimental values for the viscosity of the radioactive hydrogen isotope tritium (T2) are currently unavailable in literature. The value of this material property over a wide temperature range is of interest for applications in the fields of fusion and neutrino physics, as well as to test ab initio calculations. As a radioactive gas, tritium requires a careful experiment design to ensure safe and environmental contamination–free measurements. In this contribution, we present a spinning rotor gauge–based tritium-compatible design of a gas viscosity measurement apparatus, or ViMA, capable of covering the temperature range from 80 to 300 K.","PeriodicalId":12626,"journal":{"name":"Fusion Science and Technology","volume":"96 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135059677","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimization of Wall-Conditioning Techniques on the MT-II Tokamak","authors":"Muhammad Abdullah, Ahmad Ali, Riaz Khan, Osama Abdur Rehman, Zia-ur- Rehman, Shahab Ud-Din Khan, Sehrish Shakir, Shahzaib Zahid, Muhammad Ismail, Rafaqat Ali, Sarfraz Ahmad, Shahid Hussain","doi":"10.1080/15361055.2023.2241004","DOIUrl":"https://doi.org/10.1080/15361055.2023.2241004","url":null,"abstract":"AbstractThe MT-II is a small spherical tokamak that is currently under construction at the Pakistan Tokamak Plasma Research Institute. Wall conditioning of the MT-II vacuum vessel (VV) is an essential step to achieve a good quality vacuum for plasma experiments. This study presents an overview of the wall-conditioning techniques implemented on the MT-II VV, including baking and glow discharge cleaning (GDC). Prior to wall conditioning, the system is checked via a helium leak test machine and residual gas analyzer (RGA) to identify and remove leaks. The VV walls are baked at ~180 °C to get rapid desorption of water vapors and other impurities. After the baking process, the partial pressure of most of the carbon- and oxygen-containing impurities is reduced. In particular, the partial pressure of water vapors is reduced by 93%. Consequently, the total leak and outgassing rate is significantly reduced. To further improve the vacuum condition in the vessel, hydrogen GDC is carried out. The fill hydrogen pressure and anode voltage are optimized to get a stable glow discharge. The RGA scan shows that GDC reduces the partial pressure of H2O, O2, and CO2 by 57%, 63%, and 51%, respectively. The results signify that baking and GDC are effective techniques for wall conditioning of the MT-II VV.Keywords: MT-II tokamakbakingglow discharge cleaningleak rateresidual gas analyzer Disclosure StatementNo potential conflict of interest was reported by the authors.Additional informationFundingThis project was partially supported by a grant-in-aid from the Planning Commission, Government of Pakistan, and the International Atomic Energy Agency coordinated research project (CRP-F13018) under research grant PAK-22840.","PeriodicalId":12626,"journal":{"name":"Fusion Science and Technology","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134911091","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}