Materials Today Physics最新文献

{"title":"Significant magnon contribution to heat transfer in nickel nanowires","authors":"Wei-Tsu Peng ,&nbsp;Jiun-Hung Yi ,&nbsp;Chih-Cheng Cheng ,&nbsp;Kuan-Ju Yu ,&nbsp;Tien-Kan Chung ,&nbsp;Ming-Chang Lu","doi":"10.1016/j.mtphys.2024.101585","DOIUrl":"10.1016/j.mtphys.2024.101585","url":null,"abstract":"<div><div>Magnons, quantized spin waves arising from collective excitations of spins, are typically considered negligible contributors to heat transfer. However, recent studies on low-dimensional magnetic materials have challenged this notion, revealing significant magnon-mediated heat transport. The underlying physics behind this phenomenon, however, remains poorly understood. In this study, we observed a significant reduction in heat transfer in nickel nanowires under the influence of a magnetic field. Our theoretical model revealed a substantial magnon contribution of up to 30 % to nanowire heat transfer. The reduction in heat transfer under a magnetic field stemmed from a drastic decrease in the magnon mean free path (MFP). This decrease in MFP was primarily attributed to suppressing long wavelength magnons with a longer MFP. Our findings provide deeper insights into heat transfer mechanisms in nanoscale ferromagnetic materials and offer valuable guidance for the design of future spintronic devices.</div></div>","PeriodicalId":18253,"journal":{"name":"Materials Today Physics","volume":"49 ","pages":"Article 101585"},"PeriodicalIF":10.0,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142588418","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Infinitely rugged intra-cage potential energy landscape in metallic glasses caused by many-body interaction","authors":"Haoyu Li ,&nbsp;Hongyi Xiao ,&nbsp;Takeshi Egami ,&nbsp;Yue Fan","doi":"10.1016/j.mtphys.2024.101582","DOIUrl":"10.1016/j.mtphys.2024.101582","url":null,"abstract":"<div><div>The absence of translational symmetry in glassy materials poses a significant challenge in establishing effective structure-property relationships in real space. Consequently, the potential energy landscape (PEL) in phase space is widely utilized to comprehend the complex phenomena in glasses. The classical PEL features a two-scale profile comprising mega-basins and sub-basins, corresponding to α-relaxations (<em>e.g.</em> glass transition) and β-relaxations (<em>e.g.</em> local cage-breaking atomic rearrangements), respectively. Recent studies, however, reveal that sub-basins are not smooth and contain finer structures, the origins of which remain elusive. Here we probe the smoothness of sub-basin bottoms in glasses' PEL by introducing small intra-cage cyclic loading and then measuring the net changes in atomic-level stresses. Compared to glasses with pair interaction, glasses with many-body interaction exhibit orders-of-magnitude larger and loading-dependent stress changes even before the first cage-breaking event takes place, which reflect much more feature-rich sub-basins. We further demonstrate this stark contrast stems from the spatial distribution of individual atom's constraining force field. Specifically, at vanishing perturbations, many-body interactions disrupt the positive-definite synchrony in energy variations of the perturbed atom and the whole system, causing inherently less confined atomic responses and infinitely rugged sub-basins. The implications of these findings for the selective addition or removal of fine structures in the PEL and the subsequent tuning of glassy materials' responses to external stimuli are also explored.</div></div>","PeriodicalId":18253,"journal":{"name":"Materials Today Physics","volume":"49 ","pages":"Article 101582"},"PeriodicalIF":10.0,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142594296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reversing band bending at grain boundaries enables high-efficiency Cu2ZnSn(S,Se)4 solar cells","authors":"Rutao Meng ,&nbsp;Xuejun Xu ,&nbsp;Yue Huang ,&nbsp;Li Wu ,&nbsp;Jianpeng Li ,&nbsp;Han Xu ,&nbsp;Jiabin Dong ,&nbsp;Yue Liu ,&nbsp;Xuewen Fu ,&nbsp;Hongling Guo ,&nbsp;Gang Wang ,&nbsp;Yi Zhang","doi":"10.1016/j.mtphys.2024.101580","DOIUrl":"10.1016/j.mtphys.2024.101580","url":null,"abstract":"<div><div>Kesterite solar cells show great potential for sustainable photovoltaic technology, attributed to their excellent semiconductor properties and earth abundant composition. However, undesirable band bending at the grain boundaries (GBs) in Cu₂ZnSn(S,Se)₄ (CZTSSe) films induces serious carrier recombination because of inhomogeneous distribution of S and Se in the grain interiors (GIs) and at GBs, which results in large open-circuit voltage deficit and overall poor performance of CZTSSe solar cells. Here, a robust hydrothermal sulfurization design has successfully inverted the band bending at the GBs, with advanced cathodoluminescence measurement confirming the transition of carrier collection pathways from the GBs to the GIs, thereby achieving efficient carrier collection within the GIs. Simultaneously, this design has effectively passivated the non-radiative recombination in the GIs, smoothing the way for carrier collection. Ultimately, a 13.7 % efficiency CZTSSe solar cell with 44 % improvement is realized by this process. This study discloses that reversing the band bending at GBs is practical to tailor the carrier collection, and thus pave the pathway for high-efficient photoelectronic devices.</div></div>","PeriodicalId":18253,"journal":{"name":"Materials Today Physics","volume":"48 ","pages":"Article 101580"},"PeriodicalIF":10.0,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142541509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Corrigendum to “Structural and electronic transformations in TiO2 induced by electric current” [Mater. Today Phys., 48 (November 2024), 101546]","authors":"Tyler C. Sterling ,&nbsp;Feng Ye ,&nbsp;Seohyeon Jo ,&nbsp;Anish Parulekar ,&nbsp;Yu Zhang ,&nbsp;Gang Cao ,&nbsp;Rishi Raj ,&nbsp;Dmitry Reznik","doi":"10.1016/j.mtphys.2024.101554","DOIUrl":"10.1016/j.mtphys.2024.101554","url":null,"abstract":"","PeriodicalId":18253,"journal":{"name":"Materials Today Physics","volume":"48 ","pages":"Article 101554"},"PeriodicalIF":10.0,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synergistic effect of indium doping on thermoelectric performance of cubic GeTe-based thin films","authors":"Suman Abbas ,&nbsp;Bhawna Jarwal ,&nbsp;Thi-Thong Ho ,&nbsp;Suneesh Meledath Valiyaveettil ,&nbsp;Cheng-Rong Hsing ,&nbsp;Ta-Lei Chou ,&nbsp;Ching-Ming Wei ,&nbsp;Li-Chyong Chen ,&nbsp;Kuei-Hsien Chen","doi":"10.1016/j.mtphys.2024.101581","DOIUrl":"10.1016/j.mtphys.2024.101581","url":null,"abstract":"<div><div>Germanium Telluride (GeTe) has been widely explored as a promising lead-free thermoelectric material in its rhombohedral and cubic phases. However, the structural transition between these two phases at ∼700 K causes an abrupt change of thermal expansion coefficient, challenging its broader practical applications. Also, as characterized by multi-valence bands and strong anharmonic interaction, the high-temperature cubic phase exhibits a higher power factor, lower thermal conductivity, and ultimately superior thermoelectric performance than its rhombohedral counterpart. Prompted by these, in this work, the cubic phase of Ge_0.9Sb_0.1Te (presented as GeSbTe in the following content) nanocrystalline thin film is successfully realized by RF sputtering followed by post-annealing treatment. Additionally, indium, as an electron donor to the germanium site and an effective scattering center, further moderates carrier concentration, enhances the Seebeck coefficient and reduces thermal conductivity. The optimal composition achieves an estimated peak <span><math><mrow><mi>z</mi><mi>T</mi></mrow></math></span> of ∼1.95 and an estimated average <span><math><mrow><mi>z</mi><mi>T</mi></mrow></math></span> of ∼1.11 within the temperature range of 300 K–575 K, showcasing GeTe as a compelling candidate for applications close to room temperature.</div></div>","PeriodicalId":18253,"journal":{"name":"Materials Today Physics","volume":"49 ","pages":"Article 101581"},"PeriodicalIF":10.0,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142562243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Linear dielectric ceramics for near-zero loss high-capacitance energy storage","authors":"Xuqing Zhang ,&nbsp;Yongping Pu ,&nbsp;Pan Gao ,&nbsp;Xinye Huang ,&nbsp;Jiahui Ma ,&nbsp;Lei Zhang ,&nbsp;Zenghui Liu","doi":"10.1016/j.mtphys.2024.101579","DOIUrl":"10.1016/j.mtphys.2024.101579","url":null,"abstract":"<div><div>High energy-density (<em>W</em>_rec) dielectric capacitors have gained a focal point in the field of power electronic systems. In this study, high energy storage density materials with near-zero loss were obtained by constructing different types of defect dipoles in linear dielectric ceramics. Mg²⁺and Nb⁵⁺ are strategically chosen as acceptor/donor ions, effectively replacing Ti⁴⁺ within Ca_0.5Sr_0.5TiO₃-based ceramics. The results indicate that under an applied electric field, specific defects such as <span><math><mrow><mo>[</mo><mrow><msubsup><mrow><mi>M</mi><mi>g</mi></mrow><mrow><mi>T</mi><mi>i</mi></mrow><mo>″</mo></msubsup><mo>−</mo><msubsup><mi>V</mi><mi>O</mi><mrow><mo>·</mo><mo>·</mo></mrow></msubsup></mrow><mo>]</mo></mrow></math></span> and <span><math><mrow><mrow><msubsup><mrow><mo>[</mo><mi>N</mi><mi>b</mi></mrow><mrow><mi>T</mi><mi>i</mi></mrow><mo>·</mo></msubsup><mo>−</mo><msup><mrow><mi>T</mi><mi>i</mi></mrow><mrow><mn>3</mn><mo>+</mo></mrow></msup></mrow><mo>]</mo></mrow></math></span>, can effectively regulate <span><math><mrow><msubsup><mi>V</mi><mi>O</mi><mrow><mo>·</mo><mo>·</mo></mrow></msubsup></mrow></math></span> and electron movement, significantly reducing losses. Furthermore, high-density insulating grain boundaries, reduced <span><math><mrow><msubsup><mi>V</mi><mi>O</mi><mrow><mo>·</mo><mo>·</mo></mrow></msubsup></mrow></math></span> concentrations and diminished carrier mobility contribute to enhanced resistivity, resulting in high <em>W</em>_rec ∼7.62 J/cm³ and <em>η</em> ∼92 % at 640 kV/cm, making it one of the most promising linear dielectrics to date. Notably, <em>W</em>_rec and <em>η</em> remain remarkably stable across a broad range of frequencies (1–500 Hz), temperatures (25–175 °C) and numerous cycles (up to 10⁶). Additionally, finite element software was used to simulate the distribution of dielectric constant, electric potential, and local electric field, further verifying the correlation between microstructure and breakdown resistance. This innovative work provides a sustainable strategy to optimize the energy storage capacity of lead-free ceramics over a wide temperature range through strategic manipulation of defects.</div></div>","PeriodicalId":18253,"journal":{"name":"Materials Today Physics","volume":"49 ","pages":"Article 101579"},"PeriodicalIF":10.0,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142520125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lightweight and highly heat-resistant copolymerized polyimide foams for superior thermal insulation and acoustic absorption","authors":"Shuhuan Yun,&nbsp;Xianzhe Sheng,&nbsp;Zhenyu Xiong,&nbsp;Zhonglei Ma,&nbsp;Jianbing Qin,&nbsp;Guangcheng Zhang","doi":"10.1016/j.mtphys.2024.101578","DOIUrl":"10.1016/j.mtphys.2024.101578","url":null,"abstract":"<div><div>The development of lightweight and highly heat-resistant polyimide foams (PIFs) remains a great challenge in areas of aerospace, military ships, transportation, and industries. Herein, a series of lightweight and highly thermal-resistant copolymerized PIFs are successfully fabricated by the “stepwise heating-holding” thermal foaming of the copolymerized polyester ammonium salts (C-PEAS), using 3,3′,4,4′-benzophenone tetracarboxylic acid dianhydride (BTDA) and 2,3,3′,4′-biphenyl tetracarboxylic acid dianhydride (α-BPDA) as codianhydride, and p-phenylenediamine (PDA) as diamine. The introduction of α-BPDA increases the rigidity of PI molecule chains and foamability of C-PEAS, and significantly improves the heat resistance of PIFs. The resultant copolymerized PIFs exhibit ultra-low densities (&lt;10 kg m⁻³), excellent heat resistance (<em>T</em>_g ranging from 351.2 °C to 405.6 °C), and high thermal stability. Moreover, they possess high flame retardancies (LOI&gt;44 %) and low thermal conductivities (as low as 0.0463 W m⁻¹ K⁻¹ at 20 °C and no more than 0.0825 W m⁻¹ K⁻¹ at 200 °C), demonstrating their excellent thermal insulation properties in a wide temperature range. After the continuous heating at 200 °C for 40 min, the upper surface of PIFs present low average temperatures less than 60 °C. Additionally, the copolymerized PIFs exhibit remarkable acoustic properties with average acoustic absorption coefficients above 0.6 and noise reduction coefficients (NRC) above 0.3. Therefore, the lightweight and highly heat-resistant copolymerized PIFs show great application potentials in the extreme environments of aerospace, military ships, transportation, and industries.</div></div>","PeriodicalId":18253,"journal":{"name":"Materials Today Physics","volume":"49 ","pages":"Article 101578"},"PeriodicalIF":10.0,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142489204","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Recent advances and new frontier of flexible pressure sensors: Structure engineering, performances and applications","authors":"Tianhui Jiang ,&nbsp;Chunnan Wang ,&nbsp;Tianyi Ling ,&nbsp;Shuqing Sun ,&nbsp;Lei Yang","doi":"10.1016/j.mtphys.2024.101576","DOIUrl":"10.1016/j.mtphys.2024.101576","url":null,"abstract":"<div><div>Global research on flexible pressure sensors for evaluating human wellness and intelligent robotics is intensifying due to their advantages of excellent flexibility, lightweight design, high sensitivity and ease of integration. To facilitate practical applications, challenges associated with high-performance must be addressed, such as the trade-off between high sensitivity and a wide linear sensing range, fast response/recovery time, limited hysteresis, and stability under both dynamic and static pressure conditions. Moreover, ensuring the sensors’ reliability under various interferences and their multi-functionality to meet diverse usage requirements is essential for future applications. In this review, we summarize the latest advancements in multiple microstructures within the active layer and/or electrodes, which ensure excellent sensing performances, superior reliability and multifunctional features. Specifically, we focus on the design, working principles and sensing features of advanced micropattern, micropores, fiber-network, and hybrid microstructures in pressure sensors based on hierarchical micro-/nano-structure, conductive gradient coatings or multilayer structures. Additionally, the applications of microstructured pressure sensors in the fields of healthcare and human-machine interaction are summarized. Finally, we discuss the challenges and future prospects in the development of the next generation of flexible pressure sensors.</div></div>","PeriodicalId":18253,"journal":{"name":"Materials Today Physics","volume":"48 ","pages":"Article 101576"},"PeriodicalIF":10.0,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142487158","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhanced nonlinear optical properties of MXene (Ti3C2Tx) via surface-covalent functionalization with porphyrin","authors":"Yang Zhao ,&nbsp;Zihao Guan ,&nbsp;Zhiyuan Wei ,&nbsp;Lulu Fu ,&nbsp;Lu Chen ,&nbsp;Zhipeng Huang ,&nbsp;Mark G. Humphrey ,&nbsp;Chi Zhang","doi":"10.1016/j.mtphys.2024.101577","DOIUrl":"10.1016/j.mtphys.2024.101577","url":null,"abstract":"<div><div>The surface terminations (=O, -OH, and -F) play a key role in determining the physical and chemical properties of MXenes, which have been demonstrated with significant potential in field-effect transistors, humidity sensors, energy storage, and photocatalysis, etc. It is therefore crucial to modify these active functional groups on the surface of MXenes in order to optimize the applicability of these materials. In this study, we introduce a covalent modification strategy to successfully construct a porphyrin-functionalized Ti₃C₂T_x organic-inorganic nanohybrid (TPP-Ti₃C₂T_x) by covalently attaching porphyrin molecules to the surface groups on Ti₃C₂T_x nanosheets for the first time. As revealed by steady-state fluorescence spectra, transient fluorescence spectra, and DFT calculations, the robust covalent bonds between TPP and Ti₃C₂T_x can effectively promote the photon-induced electron and/or energy transfer within the TPP-Ti₃C₂T_x nanohybrid. The investigation on the nonlinear optical (NLO) properties of TPP-Ti₃C₂T_x nanohybrid as well as its precursors, reveals that the TPP-Ti₃C₂T_x nanohybrid exhibits the highest nonlinear absorption coefficient and the lowest optical limiting threshold among the tested samples at both 532 and 1064 nm, indicating its great potential as a broadband optical limiter for visible and near-infrared wavelengths. This work not only demonstrates the significant promise of covalently-linked TPP-Ti₃C₂T_x nanohybrid in optical limiting applications but also provides a paradigm for engineering high-performance NLO MXenes-based materials through the covalent modification strategy.</div></div>","PeriodicalId":18253,"journal":{"name":"Materials Today Physics","volume":"48 ","pages":"Article 101577"},"PeriodicalIF":10.0,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142487089","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Revealing the pinning landscape and related vortex pattern evolution in granular superconducting films","authors":"Tian He ,&nbsp;Kang-Hong Yin ,&nbsp;Xin-Sheng Gao ,&nbsp;Han-Xi Ren ,&nbsp;Ya-Xun He ,&nbsp;Jia-Ying Zhang ,&nbsp;Hao-Hao Shi ,&nbsp;Cun Xue ,&nbsp;Jun-Yi Ge","doi":"10.1016/j.mtphys.2024.101575","DOIUrl":"10.1016/j.mtphys.2024.101575","url":null,"abstract":"<div><div>Most superconducting electronics based on films exhibit granular structures. It has been suggested that grain boundaries form a network with relatively weak superconductivity, potentially acting as pinning centers. Yet, so far, detailed microscopic studies of the pinning landscape and its relation to vortex behavior remain scarce. Here, we imaged the vortex lattices (VL) in granular Nb films using magnetic force microscopy over large scanning areas at various magnetic fields. A non-monotonic evolution in the degree of vortex lattice ordering was observed with increasing vortex density, driven by a combination of vortex-vortex interactions and pinning effects. The spatial distribution of pinning potential within the film was directly mapped using a recently developed scanning quantum vortex microscope (SQVM). Instead of the network formed by grain boundaries, the pinning landscape presents a network-like structure, yet with domains significantly larger than the individual grains. The results of numerical simulations based on pinning landscape revealed by SQVM well reproduce our experiments. The pinning force per unit length at low magnetic fields was calculated. The critical current density, estimated from the relative positions of vortices, aligns well with the critical state model. Our work illustrates the relationship between the evolution of the vortex lattice with magnetic field and the structural features of granular Nb film, providing new insights into the design of high-performance superconducting electronic devices.</div></div>","PeriodicalId":18253,"journal":{"name":"Materials Today Physics","volume":"48 ","pages":"Article 101575"},"PeriodicalIF":10.0,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142487075","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}