Magnetic resonance (Gottingen, Germany)最新文献

{"title":"Correction of field instabilities in biomolecular solid-state NMR by simultaneous acquisition of a frequency reference.","authors":"Václav Římal, Morgane Callon, Alexander A Malär, Riccardo Cadalbert, Anahit Torosyan, Thomas Wiegand, Matthias Ernst, Anja Böckmann, Beat H Meier","doi":"10.5194/mr-3-15-2022","DOIUrl":"10.5194/mr-3-15-2022","url":null,"abstract":"<p><p>With the advent of faster magic-angle spinning (MAS) and higher magnetic fields, the resolution of biomolecular solid-state nuclear magnetic resonance (NMR) spectra has been continuously increasing. As a direct consequence, the always narrower spectral lines, especially in proton-detected spectroscopy, are also becoming more sensitive to temporal instabilities of the magnetic field in the sample volume. Field drifts in the order of tenths of parts per million occur after probe insertion or temperature change, during cryogen refill, or are intrinsic to the superconducting high-field magnets, particularly in the months after charging. As an alternative to a field-frequency lock based on deuterium solvent resonance rarely available for solid-state NMR, we present a strategy to compensate non-linear field drifts using simultaneous acquisition of a frequency reference (SAFR). It is based on the acquisition of an auxiliary 1D spectrum in each scan of the experiment. Typically, a small-flip-angle pulse is added at the beginning of the pulse sequence. Based on the frequency of the maximum of the solvent signal, the field evolution in time is reconstructed and used to correct the raw data after acquisition, thereby acting in its principle as a digital lock system. The general applicability of our approach is demonstrated on 2D and 3D protein spectra during various situations with a non-linear field drift. SAFR with small-flip-angle pulses causes no significant loss in sensitivity or increase in experimental time in protein spectroscopy. The correction leads to the possibility of recording high-quality spectra in a typical biomolecular experiment even during non-linear field changes in the order of 0.1 ppm h<math><msup><mi></mi><mrow><mo>-</mo><mn>1</mn></mrow></msup></math> without the need for hardware solutions, such as stabilizing the temperature of the magnet bore. The improvement of linewidths and peak shapes turns out to be especially important for <math><msup><mi></mi><mn>1</mn></msup></math>H-detected spectra under fast MAS, but the method is suitable for the detection of carbon or other nuclei as well.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"3 1","pages":"15-26"},"PeriodicalIF":0.0,"publicationDate":"2022-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10539777/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71415928","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Localising individual atoms of tryptophan side chains in the metallo-<i>β</i>-lactamase IMP-1 by pseudocontact shifts from paramagnetic lanthanoid tags at multiple sites.","authors":"Henry W Orton, Iresha D Herath, Ansis Maleckis, Shereen Jabar, Monika Szabo, Bim Graham, Colum Breen, Lydia Topping, Stephen J Butler, Gottfried Otting","doi":"10.5194/mr-3-1-2022","DOIUrl":"10.5194/mr-3-1-2022","url":null,"abstract":"<p><p>The metallo-<math><mi>β</mi></math>-lactamase IMP-1 features a flexible loop near the active site that assumes different conformations in single crystal structures, which may assist in substrate binding and enzymatic activity. To probe the position of this loop, we labelled the tryptophan residues of IMP-1 with 7-<math><msup><mi></mi><mn>13</mn></msup></math>C-indole and the protein with lanthanoid tags at three different sites. The magnetic susceptibility anisotropy (<math><mrow><mi>Δ</mi><mi>χ</mi></mrow></math>) tensors were determined by measuring pseudocontact shifts (PCSs) of backbone amide protons. The <math><mrow><mi>Δ</mi><mi>χ</mi></mrow></math> tensors were subsequently used to identify the atomic coordinates of the tryptophan side chains in the protein. The PCSs were sufficient to determine the location of Trp28, which is in the active site loop targeted by our experiments, with high accuracy. Its average atomic coordinates showed barely significant changes in response to the inhibitor captopril. It was found that localisation spaces could be defined with better accuracy by including only the PCSs of a single paramagnetic lanthanoid ion for each tag and tagging site. The effect was attributed to the shallow angle with which PCS isosurfaces tend to intersect if generated by tags and tagging sites that are identical except for the paramagnetic lanthanoid ion.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"3 1","pages":"1-13"},"PeriodicalIF":0.0,"publicationDate":"2022-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10583275/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71415930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"NUScon: a community-driven platform for quantitative evaluation of nonuniform sampling in NMR.","authors":"Yulia Pustovalova,&nbsp;Frank Delaglio,&nbsp;D Levi Craft,&nbsp;Haribabu Arthanari,&nbsp;Ad Bax,&nbsp;Martin Billeter,&nbsp;Mark J Bostock,&nbsp;Hesam Dashti,&nbsp;D Flemming Hansen,&nbsp;Sven G Hyberts,&nbsp;Bruce A Johnson,&nbsp;Krzysztof Kazimierczuk,&nbsp;Hengfa Lu,&nbsp;Mark Maciejewski,&nbsp;Tomas M Miljenović,&nbsp;Mehdi Mobli,&nbsp;Daniel Nietlispach,&nbsp;Vladislav Orekhov,&nbsp;Robert Powers,&nbsp;Xiaobo Qu,&nbsp;Scott Anthony Robson,&nbsp;David Rovnyak,&nbsp;Gerhard Wagner,&nbsp;Jinfa Ying,&nbsp;Matthew Zambrello,&nbsp;Jeffrey C Hoch,&nbsp;David L Donoho,&nbsp;Adam D Schuyler","doi":"10.5194/mr-2-843-2021","DOIUrl":"10.5194/mr-2-843-2021","url":null,"abstract":"<p><p>Although the concepts of nonuniform sampling (NUS​​​​​​​) and non-Fourier spectral reconstruction in multidimensional NMR began to emerge 4 decades ago , it is only relatively recently that NUS has become more commonplace. Advantages of NUS include the ability to tailor experiments to reduce data collection time and to improve spectral quality, whether through detection of closely spaced peaks (i.e., \"resolution\") or peaks of weak intensity (i.e., \"sensitivity\"). Wider adoption of these methods is the result of improvements in computational performance, a growing abundance and flexibility of software, support from NMR spectrometer vendors, and the increased data sampling demands imposed by higher magnetic fields. However, the identification of best practices still remains a significant and unmet challenge. Unlike the discrete Fourier transform, non-Fourier methods used to reconstruct spectra from NUS data are nonlinear, depend on the complexity and nature of the signals, and lack quantitative or formal theory describing their performance. Seemingly subtle algorithmic differences may lead to significant variabilities in spectral qualities and artifacts. A community-based critical assessment of NUS challenge problems has been initiated, called the \"Nonuniform Sampling Contest\" (NUScon), with the objective of determining best practices for processing and analyzing NUS experiments. We address this objective by constructing challenges from NMR experiments that we inject with synthetic signals, and we process these challenges using workflows submitted by the community. In the initial rounds of NUScon our aim is to establish objective criteria for evaluating the quality of spectral reconstructions. We present here a software package for performing the quantitative analyses, and we present the results from the first two rounds of NUScon. We discuss the challenges that remain and present a roadmap for continued community-driven development with the ultimate aim of providing best practices in this rapidly evolving field. The NUScon software package and all data from evaluating the challenge problems are hosted on the NMRbox platform.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"2 2","pages":"843-861"},"PeriodicalIF":0.0,"publicationDate":"2021-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10583271/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71415920","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Correction of field instabilities in biomolecular solid-state NMR by simultaneous acquisition of a frequency reference","authors":"V. Římal, M. Callon, Alexander A. Malär, R. Cadalbert, A. Torosyan, Thomas Wiegand, M. Ernst, A. Böckmann, B. Meier","doi":"10.5194/mr-2021-64","DOIUrl":"https://doi.org/10.5194/mr-2021-64","url":null,"abstract":"Abstract. With the advent of faster magic-angle spinning (MAS) and higher magnetic fields, the resolution of biomolecular solid-state nuclear magnetic resonance (NMR) spectra has been continuously increasing. As a direct consequence, the always narrower spectral lines, especially in proton-detected spectroscopy, are also becoming more sensitive to temporal instabilities of the magnetic field in the sample volume. Field drifts in the order of tenths of ppm occur after probe insertion or temperature change, during cryogen refill, or are intrinsic to the superconducting high-field magnets, particularly in the months after charging. As an alternative to a field‒frequency lock based on deuterium solvent resonance rarely available for solid-state NMR, we present a strategy to compensate non-linear field drifts using simultaneous acquisition of a frequency reference (SAFR). It is based on the acquisition of an auxiliary 1D spectrum in each scan of the experiment. Typically, a small-flip-angle pulse is added at the beginning of the pulse sequence. Based on the frequency of the maximum of the solvent signal, the field evolu-tion in time is reconstructed and used to correct the raw data after acquisition, thereby acting in its principle as a digital lock system. The general applicability of our approach is demonstrated on 2D and 3D protein spectra during various situations with a non-linear field drift. SAFR with small-flip-angle pulses causes no significant loss in sensitivity or increase in exper-imental time in protein spectroscopy. The correction leads to the possibility of recording high-quality spectra in a typical biomolecular experiment even during non-linear field changes in the order of 0.1 ppm h−1 without the need for hardware solu-tions, such as stabilizing the temperature of the magnet bore. The improvement of linewidths and peak shapes turns out to be especially important for 1H-detected spectra under fast MAS, but the method is suitable for the detection of carbon or other nuclei as well.\u0000","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46735055","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spin noise gradient echoes.","authors":"Victor V Rodin,&nbsp;Stephan J Ginthör,&nbsp;Matthias Bechmann,&nbsp;Hervé Desvaux,&nbsp;Norbert Müller","doi":"10.5194/mr-2-827-2021","DOIUrl":"10.5194/mr-2-827-2021","url":null,"abstract":"<p><p>Nuclear spin noise spectroscopy in the absence of radio frequency pulses was studied under the influence of pulsed field gradients (PFGs) on pure and mixed liquids. Under conditions where the radiation-damping-induced line broadening is smaller than the gradient-dependent inhomogeneous broadening, echo responses can be observed in difference spectra between experiments employing pulsed field gradient pairs of the same and opposite signs. These observed spin noise gradient echoes (SNGEs) were analyzed through a simple model to describe the effects of transient phenomena. Experiments performed on high-resolution nuclear magnetic resonance (NMR) probes demonstrate how refocused spin noise behaves and how it can be exploited to determine sample properties. In bulk liquids and their mixtures, transverse relaxation times and translational diffusion constants can be determined from SNGE spectra recorded following tailored sequences of magnetic field gradient pulses.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"2 2","pages":"827-834"},"PeriodicalIF":0.0,"publicationDate":"2021-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10539801/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71415926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Selective excitation enables encoding and measurement of multiple diffusion parameters in a single experiment.","authors":"Neil MacKinnon, Mehrdad Alinaghian, Pedro Silva, Thomas Gloge, Burkhard Luy, Mazin Jouda, Jan G Korvink","doi":"10.5194/mr-2-835-2021","DOIUrl":"10.5194/mr-2-835-2021","url":null,"abstract":"<p><p>Band selectivity to address specific resonances in a spectrum enables one to encode individual settings for diffusion experiments. In a single experiment, this could include different gradient strengths (enabling coverage of a larger range of diffusion constants), different diffusion delays, or different gradient directions (enabling anisotropic diffusion measurement). In this report, a selective variant of the bipolar pulsed gradient eddy current delay (BPP-LED) experiment, enabling selective encoding of three resonances, was implemented. As proof of principle, the diffusion encoding gradient amplitude was assigned a range dependent on the selected signal, thereby allowing the extraction of the diffusion coefficient for water and a tripeptide (Met-Ala-Ser) with optimal settings in a single experiment.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"2 2","pages":"835-842"},"PeriodicalIF":0.0,"publicationDate":"2021-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10539772/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71415923","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A cryogen-free, semi-automated apparatus for bullet-dynamic nuclear polarization with improved resolution.","authors":"Karel Kouřil, Michel Gramberg, Michael Jurkutat, Hana Kouřilová, Benno Meier","doi":"10.5194/mr-2-815-2021","DOIUrl":"10.5194/mr-2-815-2021","url":null,"abstract":"<p><p>In dissolution-dynamic nuclear polarization, a hyperpolarized solid is dissolved with a jet of hot solvent. The solution is then transferred to a secondary magnet, where spectra can be recorded with improved sensitivity. In bullet-dynamic nuclear polarization this order is reversed. Pressurized gas is used to rapidly transfer the hyperpolarized solid to the secondary magnet, and the hyperpolarized solid is dissolved only upon arrival. A potential advantage of this approach is that it may avoid excessive dilution and the associated signal loss, in particular for small sample quantities. Previously, we have shown that liquid-state NMR spectra with polarization levels of up to 30 % may be recorded within less than 1 s after the departure of the hyperpolarized solid from the polarizing magnet. The resolution of the recorded spectra however was limited. The system consumed significant amounts of liquid helium, and substantial manual work was required in between experiments to prepare for the next shot. Here, we present a new bullet-DNP (dynamic nuclear polarization) system that addresses these limitations.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"2 2","pages":"815-825"},"PeriodicalIF":0.0,"publicationDate":"2021-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10539728/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71415915","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fluorine NMR study of proline-rich sequences using fluoroprolines.","authors":"Davy Sinnaeve, Abir Ben Bouzayene, Emile Ottoy, Gert-Jan Hofman, Eva Erdmann, Bruno Linclau, Ilya Kuprov, José C Martins, Vladimir Torbeev, Bruno Kieffer","doi":"10.5194/mr-2-795-2021","DOIUrl":"10.5194/mr-2-795-2021","url":null,"abstract":"<p><p>Proline homopolymer motifs are found in many proteins; their peculiar conformational and dynamic properties are often directly involved in those proteins' functions. However, the dynamics of proline homopolymers is hard to study by NMR due to a lack of amide protons and small chemical shift dispersion. Exploiting the spectroscopic properties of fluorinated prolines opens interesting perspectives to address these issues. Fluorinated prolines are already widely used in protein structure engineering - they introduce conformational and dynamical biases - but their use as <math><msup><mi></mi><mn>19</mn></msup></math>F NMR reporters of proline conformation has not yet been explored. In this work, we look at model peptides where C<math><mi>γ</mi></math>-fluorinated prolines with opposite configurations of the chiral C<math><mi>γ</mi></math> centre have been introduced at two positions in distinct polyproline segments. By looking at the effects of swapping these (4<math><mi>R</mi></math>)-fluoroproline and (4<math><mi>S</mi></math>)-fluoroproline within the polyproline segments, we were able to separate the intrinsic conformational properties of the polyproline sequence from the conformational alterations instilled by fluorination. We assess the fluoroproline <math><msup><mi></mi><mn>19</mn></msup></math>F relaxation properties, and we exploit the latter in elucidating binding kinetics to the SH3 (Src homology 3) domain.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"2 2","pages":"795-813"},"PeriodicalIF":0.0,"publicationDate":"2021-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10539733/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71415918","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of conformational exchange processes using methyl-TROSY-based Hahn echo measurements of quadruple-quantum relaxation.","authors":"Christopher A Waudby, John Christodoulou","doi":"10.5194/mr-2-777-2021","DOIUrl":"10.5194/mr-2-777-2021","url":null,"abstract":"<p><p>Transverse nuclear spin relaxation is a sensitive probe of chemical exchange on timescales on the order of microseconds to milliseconds. Here we present an experiment for the simultaneous measurement of the relaxation rates of two quadruple-quantum transitions in <math><msup><mi></mi><mn>13</mn></msup></math>CH<math><msub><mi></mi><mn>3</mn></msub></math>-labelled methyl groups. These coherences are protected against relaxation by intra-methyl dipolar interactions and so have unexpectedly long lifetimes within perdeuterated biomacromolecules. However, these coherences also have an order of magnitude higher sensitivity to chemical exchange broadening than lower order coherences and therefore provide ideal probes of dynamic processes. We show that analysis of the static magnetic field dependence of zero-, double- and quadruple-quantum Hahn echo relaxation rates provides a robust indication of chemical exchange and can determine the signed relative magnitudes of proton and carbon chemical shift differences between ground and excited states. We also demonstrate that this analysis can be combined with established Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion measurements, providing improved precision in parameter estimates, particularly in the determination of <math><msup><mi></mi><mn>1</mn></msup></math>H chemical shift differences.</p>","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":"2 2","pages":"777-793"},"PeriodicalIF":0.0,"publicationDate":"2021-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10583286/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71415916","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Insight into the structure of black coatings of ancient Egyptian mummies by advanced Electron magnetic resonance of vanadyl complexes","authors":"Charles-Emmanuel Dutoit, L. Binet, H. Vezin, Océane Anduze, A. Lattuati-Derieux, D. Gourier","doi":"10.21203/rs.3.rs-1023443/v1","DOIUrl":"https://doi.org/10.21203/rs.3.rs-1023443/v1","url":null,"abstract":"\u0000 Advanced EPR techniques such as ENDOR and pulsed EPR are used to investigate the enigmatic black coatings of ancient Egyptian mummies, consisting in a complex and heterogeneous mixtures of conifer resins, wax, fat and oil with variable amounts of bitumen. Natural bitumen always contains traces of vanadyl porphyrin complexes that we used here as internal probes to explore the nanoscale environment of V4+ ions in these black coatings by hyperfine spectroscopy. Four types of vanadyl porphyrins were identified from the analysis of 14N hyperfine interactions. Three types (referred to as VO-P1, VO-P2 and VO-P3) are present in natural bitumen from the Dead Sea, among which VO-P1 and VO-P2 are also present in black coatings of mummies. The absence of VO-P3 in mummies, which is replaced by another complex VO-P4, may be due to its transformation during preparation of the black matter for embalming. Analysis of 1H hyperfine interaction shows that bitumen and other natural substances are intimately mixed in these black coatings, with bitumen aggregate sizes not larger than a few nanometres.","PeriodicalId":93333,"journal":{"name":"Magnetic resonance (Gottingen, Germany)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41965183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}