Progress in Surface Science最新文献

{"title":"Wishful Thinking? Inside the Black Box of Exposure Assessment.","authors":"Annemarie Money, Christine Robinson, Raymond Agius, Frank de Vocht","doi":"10.1093/annhyg/mev098","DOIUrl":"10.1093/annhyg/mev098","url":null,"abstract":"<p><strong>Background: </strong>Decision-making processes used by experts when undertaking occupational exposure assessment are relatively unknown, but it is often assumed that there is a common underlying method that experts employ. However, differences in training and experience of assessors make it unlikely that one general method for expert assessment would exist. Therefore, there are concerns about formalizing, validating, and comparing expert estimates within and between studies that are difficult, if not impossible, to characterize. Heuristics on the other hand (the processes involved in decision making) have been extensively studied. Heuristics are deployed by everyone as short-cuts to make the often complex process of decision-making simpler, quicker, and less burdensome. Experts' assessments are often subject to various simplifying heuristics as a way to reach a decision in the absence of sufficient data. Therefore, investigating the underlying heuristics or decision-making processes involved may help to shed light on the 'black box' of exposure assessment.</p><p><strong>Methods: </strong>A mixed method study was conducted utilizing both a web-based exposure assessment exercise incorporating quantitative and semiqualitative elements of data collection, and qualitative semi-structured interviews with exposure assessors. Qualitative data were analyzed using thematic analysis.</p><p><strong>Results: </strong>Twenty-five experts completed the web-based exposure assessment exercise and 8 of these 25 were randomly selected to participate in the follow-up interview. Familiar key themes relating to the exposure assessment exercise emerged; 'intensity'; 'probability'; 'agent'; 'process'; and 'duration' of exposure. However, an important aspect of the detailed follow-up interviews revealed a lack of structure and order with which participants described their decision making. Participants mostly described some form of an iterative process, heavily relying on the anchoring and adjustment heuristic, which differed between experts.</p><p><strong>Conclusion: </strong>In spite of having undertaken comparable training (in occupational hygiene or exposure assessment), experts use different methods to assess exposure. Decision making appears to be an iterative process with heavy reliance on the key heuristic of anchoring and adjustment. Using multiple experts to assess exposure while providing some form of anchoring scenario to build from, and additional training in understanding the impact of simple heuristics on the process of decision making, is likely to produce a more methodical approach to assessment; thereby improving consistency and transparency in expert exposure assessment.</p>","PeriodicalId":416,"journal":{"name":"Progress in Surface Science","volume":"45 1","pages":"421-31"},"PeriodicalIF":0.0,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4815939/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75480594","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Superhydrophocity via gas-phase monomers grafting onto carbon nanotubes","authors":"Jinlong Zha ,&nbsp;Nicolas Batisse ,&nbsp;Daniel Claves ,&nbsp;Marc Dubois ,&nbsp;Lawrence Frezet ,&nbsp;Alexander P. Kharitonov ,&nbsp;Leonid N. Alekseiko","doi":"10.1016/j.progsurf.2016.03.002","DOIUrl":"https://doi.org/10.1016/j.progsurf.2016.03.002","url":null,"abstract":"<div><p><span>Superhydrophobic<span> films were prepared using dispersions of fluorinated multi-walled carbon nanotubes<span><span> (MWCNTs) or nanofibers<span><span> (CNFs) in toluene. The grafting of polystyrene allowed stable dispersions to be obtained. The grafting of polystyrene (PS), polyacrylic acid (PAA) and polyaniline (PANI) onto nanofibers and MWCNTs was first evidenced by </span>solid state NMR<span> and Infrared Spectroscopy. The graft polymerization of styrene, </span></span></span>acrylic acid<span><span> and aniline monomers<span> was initiated by radicals (dangling bonds) formed due to the initial fluorination<span>. The process appeared as highly versatile and efficient for different polymers. The consumption of those radicals in the course of grafting was evidenced by EPR, through decrease of the spin density. The hydrophobic/hydrophilic character was tuned according to the grafted polymer nature, i.e. hydrophobic with PS or hydrophilic with PAA. Finally, in order to reach superhydrophobicity, films were prepared from CNFs or MWCNTs, irrespective of their average diameter, that allowed adequate structuring of the surface. The presence of </span></span></span>fluorine atoms on their surface also favors superhydrophobicity. Water contact angles of 155</span></span></span></span> <!-->±<!--> <!-->2° and 159<!--> <!-->±<!--> <!-->2° were measured for the films casted from fluorinated CNFs or MWCNTs with grafted polystyrene, respectively.</p></div>","PeriodicalId":416,"journal":{"name":"Progress in Surface Science","volume":"91 2","pages":"Pages 57-71"},"PeriodicalIF":6.4,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.progsurf.2016.03.002","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"2401962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Surface physics of semiconducting nanowires","authors":"Michele Amato ,&nbsp;Riccardo Rurali","doi":"10.1016/j.progsurf.2015.11.001","DOIUrl":"https://doi.org/10.1016/j.progsurf.2015.11.001","url":null,"abstract":"<div><p>Semiconducting nanowires<span> (NWs) are firm candidates for novel nanoelectronic devices and a fruitful playground for fundamental physics.</span></p><p>Ultra-thin nanowires, with diameters below 10<!--> <!-->nm, present exotic quantum effects due to the confinement of the wave functions, e.g. widening of the electronic band-gap, deepening of the dopant states. However, although several reports of sub-10<!--> <!-->nm wires exist to date, the most common NWs have diameters that range from 20 to 200<!--> <!-->nm, where these quantum effects are absent or play a very minor role. Yet, the research activity on this field is very intense and these materials still promise to provide an important paradigm shift for the design of emerging electronic devices and different kinds of applications. A legitimate question is then: what makes a nanowire different from bulk systems? The answer is certainly the large surface-to-volume ratio.</p><p>In this article we discuss the most salient features of surface physics and chemistry<span> in group-IV semiconducting nanowires, focusing mostly on Si NWs. First we review the state-of-the-art of NW growth to achieve a smooth and controlled surface morphology. Next we discuss the importance of a proper surface passivation and its role on the NW electronic properties. Finally, stressing the importance of a large surface-to-volume ratio and emphasizing the fact that in a NW the surface is where most of the action takes place, we discuss molecular sensing and molecular doping.</span></p></div>","PeriodicalId":416,"journal":{"name":"Progress in Surface Science","volume":"91 1","pages":"Pages 1-28"},"PeriodicalIF":6.4,"publicationDate":"2016-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.progsurf.2015.11.001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"2401963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Oxygen adsorption on surfaces studied by a spin- and alignment-controlled O2 beam","authors":"Mitsunori Kurahashi","doi":"10.1016/j.progsurf.2016.03.001","DOIUrl":"https://doi.org/10.1016/j.progsurf.2016.03.001","url":null,"abstract":"<div><p><span>Molecular oxygen (O</span>₂<span>) is a paramagnetic linear molecule, yet the effect of its molecular alignment and electron spin on the dynamics of O</span>₂ adsorption has remained unclear. Recently, it has been however shown that the use of magnetic hexapolar field allows us to prepare a single spin-rotational state [(<span><math><mrow><mi>J</mi><mtext>,</mtext><mi>M</mi></mrow></math></span>)<!--> <!-->=<!--> <!-->(2,<!--> <!-->2)] selected O₂<span> beam for which both the molecular alignment and the spin state of O</span>₂ are well defined. State-resolved studies of O₂ sticking on Si(1<!--> <!-->0<!--> <!-->0), Al(1<!--> <!-->1<!--> <!-->1), Ni(1<!--> <!-->1<!--> <!-->1) surfaces conducted with this beam have clarified that the O₂<span> sticking probability depends strongly on the molecular alignment and the spin orientation of O</span>₂ relative to the surface. The mechanism of O₂ adsorption on Al(1<!--> <!-->1<!--> <span>1) has been disputed in the past few decades, but the observed steric effect has provided a reasonable picture for it. The preparation method of the state-selected O</span>₂ beam and its application to the alignment- and spin-resolved O₂ sticking studies are reviewed.</p></div>","PeriodicalId":416,"journal":{"name":"Progress in Surface Science","volume":"91 1","pages":"Pages 29-55"},"PeriodicalIF":6.4,"publicationDate":"2016-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.progsurf.2016.03.001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"2120071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Growth morphology and properties of metals on graphene","authors":"Xiaojie Liu ,&nbsp;Yong Han ,&nbsp;James W. Evans ,&nbsp;Albert K. Engstfeld ,&nbsp;R. Juergen Behm ,&nbsp;Michael C. Tringides ,&nbsp;Myron Hupalo ,&nbsp;Hai-Qing Lin ,&nbsp;Li Huang ,&nbsp;Kai-Ming Ho ,&nbsp;David Appy ,&nbsp;Patricia A. Thiel ,&nbsp;Cai-Zhuang Wang","doi":"10.1016/j.progsurf.2015.07.001","DOIUrl":"https://doi.org/10.1016/j.progsurf.2015.07.001","url":null,"abstract":"<div><p><span>Graphene, a single atomic layer of graphite, has been the focus of recent intensive studies due to its novel electronic and structural properties. Metals grown on graphene also have been of interest because of their potential use as metal contacts in graphene devices, for spintronics applications, and for catalysis. All of these applications require good understanding and control of the metal growth morphology, which in part reflects the strength of the metal–graphene bond. Also of importance is whether the interaction between graphene and metal is sufficiently strong to modify the electronic structure of graphene. In this review, we will discuss recent experimental and computational studies related to deposition of metals on graphene supported on various substrates (SiC, SiO</span>₂<span>, and hexagonal close-packed metal surfaces). Of specific interest are the metal–graphene interactions (adsorption energies and diffusion<span> barriers of metal adatoms), and the crystal structures and thermal stability of the metal nanoclusters.</span></span></p></div>","PeriodicalId":416,"journal":{"name":"Progress in Surface Science","volume":"90 4","pages":"Pages 397-443"},"PeriodicalIF":6.4,"publicationDate":"2015-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.progsurf.2015.07.001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"2401964","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Polar discontinuities and 1D interfaces in monolayered materials","authors":"Rafael Martinez-Gordillo ,&nbsp;Miguel Pruneda","doi":"10.1016/j.progsurf.2015.08.001","DOIUrl":"https://doi.org/10.1016/j.progsurf.2015.08.001","url":null,"abstract":"<div><p>Interfaces are the birthplace of a multitude of fascinating discoveries in fundamental science, and have enabled modern electronic devices, from transistors, to lasers, capacitors or solar cells. These interfaces between bulk materials are always bi-dimensional (2D) ‘surfaces’. However the advent of graphene and other 2D crystals opened up a world of possibilities, as in this case the interfaces become one-dimensional (1D) lines. Although the properties of 1D nanoribbons have been extensively discussed in the last few years, 1D interfaces within infinite 2D systems had remained mostly unexplored until very recently. These include grain boundaries in polycrystalline samples, or interfaces in hybrid 2D sheets composed by segregated domains of different materials (as for example graphene/BN hybrids, or chemically different transition metal dichalcogenides). As for their 2D counterparts, some of these 1D interfaces exhibit polar characteristics, and can give rise to fascinating new physical properties. Here, recent experimental discoveries and theoretical predictions on the polar discontinuities that arise at these 1D interfaces will be reviewed, and the perspectives of this new research topic, discussed.</p></div>","PeriodicalId":416,"journal":{"name":"Progress in Surface Science","volume":"90 4","pages":"Pages 444-463"},"PeriodicalIF":6.4,"publicationDate":"2015-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.progsurf.2015.08.001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"2621777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ultrafast dynamics during the photoinduced phase transition in VO2","authors":"Daniel Wegkamp,&nbsp;Julia Stähler","doi":"10.1016/j.progsurf.2015.10.001","DOIUrl":"https://doi.org/10.1016/j.progsurf.2015.10.001","url":null,"abstract":"<div><p>The phase transition of VO₂ from a monoclinic insulator to a rutile metal, which occurs thermally at <span><math><mrow><msub><mrow><mi>T</mi></mrow><mrow><mtext>C</mtext></mrow></msub></mrow></math></span> <!-->=<!--> <!-->340<!--> <!-->K, can also be driven by strong photoexcitation. The ultrafast dynamics during this photoinduced phase transition (PIPT) have attracted great scientific attention for decades, as this approach promises to answer the question of whether the insulator-to-metal (IMT) transition is caused by electronic or crystallographic processes through disentanglement of the different contributions in the time domain. We review our recent results achieved by femtosecond time-resolved photoelectron, optical, and coherent phonon spectroscopy and discuss them within the framework of a selection of latest, complementary studies of the ultrafast PIPT in VO₂. We show that the population change of electrons and holes caused by photoexcitation launches a highly non-equilibrium plasma phase characterized by enhanced screening due to quasi-free carriers and followed by two branches of non-equilibrium dynamics: (i) an instantaneous (within the time resolution) collapse of the insulating gap that precedes charge carrier relaxation and significant ionic motion and (ii) an instantaneous lattice potential symmetry change that represents the onset of the crystallographic phase transition through ionic motion on longer timescales. We discuss the interconnection between these two non-thermal pathways with particular focus on the meaning of the critical fluence of the PIPT in different types of experiments. Based on this, we conclude that the PIPT threshold identified in optical experiments is most probably determined by the excitation density required to drive <em>the lattice potential change rather than the IMT</em>. These considerations suggest that the IMT can be driven by weaker excitation, predicting a transiently metallic, monoclinic state of VO₂ that is not stabilized by the non-thermal structural transition and, thus, decays on ultrafast timescales.</p></div>","PeriodicalId":416,"journal":{"name":"Progress in Surface Science","volume":"90 4","pages":"Pages 464-502"},"PeriodicalIF":6.4,"publicationDate":"2015-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.progsurf.2015.10.001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"2401967","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Direct observation and control of hydrogen-bond dynamics using low-temperature scanning tunneling microscopy","authors":"Takashi Kumagai","doi":"10.1016/j.progsurf.2015.04.001","DOIUrl":"https://doi.org/10.1016/j.progsurf.2015.04.001","url":null,"abstract":"<div><p><span>Hydrogen(H)-bond dynamics are involved in many elementary processes in chemistry and biology. Because of its fundamental importance, a variety of experimental and theoretical approaches have been employed to study the dynamics in gas, liquid, solid phases, and their interfaces. This review describes the recent progress of direct observation and control of H-bond dynamics in several model systems on a metal surface by using low-temperature scanning tunneling microscopy (STM). General aspects of H-bond dynamics and the experimental methods are briefly described in chapter 1 and 2. In the subsequent four chapters, I present direct observation of an H-bond exchange reaction within a single water dimer (chapter 3), a symmetric H bond (chapter 4) and H-atom relay reactions (chapter 5) within water–hydroxyl complexes, and an intramolecular H-atom transfer reaction (tautomerization) within a single porphycene molecule (chapter 6). These results provide novel microscopic insights into H-bond dynamics </span><em>at the single-molecule level</em>, and highlight significant impact on the process from quantum effects, namely tunneling and zero-point vibration, resulting from the small mass of H atom. Additionally, local environmental effect on H-bond dynamics is also examined by using atom/molecule manipulation with the STM.</p></div>","PeriodicalId":416,"journal":{"name":"Progress in Surface Science","volume":"90 3","pages":"Pages 239-291"},"PeriodicalIF":6.4,"publicationDate":"2015-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.progsurf.2015.04.001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"2401965","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Highly charged ion induced nanostructures at surfaces by strong electronic excitations","authors":"Richard A. Wilhelm ,&nbsp;Ayman S. El-Said ,&nbsp;Franciszek Krok ,&nbsp;René Heller ,&nbsp;Elisabeth Gruber ,&nbsp;Friedrich Aumayr ,&nbsp;Stefan Facsko","doi":"10.1016/j.progsurf.2015.06.001","DOIUrl":"https://doi.org/10.1016/j.progsurf.2015.06.001","url":null,"abstract":"<div><p><span><span>Nanostructure<span> formation by single slow highly charged ion impacts<span> can be associated with high density of electronic excitations at the impact points of the ions. Experimental results show that depending on the target material these electronic excitations may lead to very large desorption yields in the order of a few 1000 atoms per ion or the formation of nanohillocks at the impact site. Even in ultra-thin insulating membranes the formation of nanometer sized pores is observed after ion impact. In this paper, we show recent results on nanostructure formation by highly charged ions and compare them to structures and defects observed after intense electron and light </span></span></span>ion irradiation<span><span> of ionic crystals and graphene. Additional data on energy loss, charge exchange and secondary </span>electron emission of highly charged ions clearly show that the </span></span>ion charge dominates the defect formation at the surface.</p></div>","PeriodicalId":416,"journal":{"name":"Progress in Surface Science","volume":"90 3","pages":"Pages 377-395"},"PeriodicalIF":6.4,"publicationDate":"2015-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.progsurf.2015.06.001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"2621778","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ab initio quantum transport calculations using plane waves","authors":"A. Garcia-Lekue ,&nbsp;M.G. Vergniory ,&nbsp;X.W. Jiang ,&nbsp;L.W. Wang","doi":"10.1016/j.progsurf.2015.05.002","DOIUrl":"https://doi.org/10.1016/j.progsurf.2015.05.002","url":null,"abstract":"<div><p>We present an <em>ab initio</em><span><span><span><span> method to calculate elastic quantum transport at the </span>nanoscale. The method is based on a combination of </span>density functional theory using plane wave nonlocal </span>pseudopotentials<span><span> and the use of auxiliary periodic boundary conditions to obtain the scattering states. The method can be applied to any applied bias voltage and the charge density and potential profile can either be calculated self-consistently, or using an approximated self-consistent field (SCF) approach. Based on the scattering states one can straightforwardly calculate the transmission coefficients and the corresponding electronic current. The overall scheme allows us to obtain accurate and numerically stable solutions for the elastic transport, with a computational time similar to that of a ground state calculation. This method is particularly suitable for calculations of tunneling currents through vacuum, that some of the </span>nonequilibrium<span><span><span> Greens function (NEGF) approaches based on atomic basis sets might have difficulty to deal with. Several examples are provided using this method from </span>electron tunneling, to </span>molecular electronics, to electronic devices: (i) On a Au nanojunction, the tunneling current dependence on the electrode–electrode distance is investigated. (ii) The tunneling through field emission resonances (FERs) is studied via an accurate description of the surface vacuum states. (iii) Based on quantum transport calculations, we have designed a molecular conformational switch, which can turn on and off a molecular junction by applying a perpendicular electric field. (iv) Finally, we have used the method to simulate tunnel field-effect transistors (TFETs) based on two-dimensional transition-metal dichalcogenides (TMDCs), where we have studied the performance and scaling limits of such nanodevices and proposed atomic doping to enhance the transistor performance.</span></span></span></p></div>","PeriodicalId":416,"journal":{"name":"Progress in Surface Science","volume":"90 3","pages":"Pages 292-318"},"PeriodicalIF":6.4,"publicationDate":"2015-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.progsurf.2015.05.002","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"3390755","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}