Journal of magnetic resonance最新文献

{"title":"Protecting air/moisture-sensitive samples using perdeuterated paraffin wax for solid-state NMR experiments under magic-angle spinning","authors":"Emma A. Foley ,&nbsp;Joseph F. Thuma ,&nbsp;Jacob Mayer ,&nbsp;Mita Halder ,&nbsp;Wenyu Huang ,&nbsp;Frédéric A. Perras ,&nbsp;Damien B. Culver ,&nbsp;Takeshi Kobayashi","doi":"10.1016/j.jmr.2025.107935","DOIUrl":"10.1016/j.jmr.2025.107935","url":null,"abstract":"<div><div>Solid-state nuclear magnetic resonance (SSNMR) spectroscopy is a powerful technique for materials characterization, yet its application to air- and moisture-sensitive materials is often hindered by the difficulty in maintaining an inert environment during magic-angle spinning (MAS). This is particularly true for fast-MAS rotors that do not generally provide tight seals. Herein, we present a generalizable approach employing perdeuterated paraffin waxes—<em>n</em>-icosane-d42 and <em>c</em>-dodecane-d24—as protective embedding media to analyze sensitive organometallic catalysts using SSNMR. We demonstrate that these waxes significantly slow oxidative degradation under MAS conditions. Weak background ¹H and ¹³C NMR signals from the waxes are effectively suppressed using double-quantum filtration and cross-polarization techniques. These findings offer a robust method for expanding the scope of SSNMR to air-sensitive systems, with implications for the structural study of reactive materials and catalysts.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"379 ","pages":"Article 107935"},"PeriodicalIF":2.0,"publicationDate":"2025-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144632715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Towards complete suppression of diagonal peaks in solid-state MAS NMR homonuclear chemical shift correlation spectra","authors":"Shengyu Zhang ,&nbsp;Yuchen Li ,&nbsp;Yansheng Ye ,&nbsp;Fang Tian ,&nbsp;Xinhua Peng ,&nbsp;Riqiang Fu","doi":"10.1016/j.jmr.2025.107926","DOIUrl":"10.1016/j.jmr.2025.107926","url":null,"abstract":"<div><div>The feasibility of applying the spin-echo based diagonal peak suppression method in solid-state MAS NMR homonuclear chemical shift correlation experiments is demonstrated. A complete phase cycling is designed to generate sine- and cosine-modulations of the chemical shift difference between the spin-diffused signals, enabling the quadrature detection in the indirect dimension. Meanwhile, all signals not involved in polarization transfer are refocused at the center of the indirect dimension. A data processing algorithm is developed to extract and suppress these spin-echo refocused signals without affecting nearby spin-diffused cross peaks. The processed spectrum is then converted into a conventional two-dimensional homonuclear chemical shift correlation spectrum, free of diagonal peaks. The effectiveness of this method is illustrated using a uniformly ¹³C-labeled Fmoc-leucine sample and a sample of human Atg8 homolog LC3B, directly conjugated to the amino headgroup of phosphatidylethanolamine (PE) lipids in liposomes.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"378 ","pages":"Article 107926"},"PeriodicalIF":2.0,"publicationDate":"2025-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144518107","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A mathematical model of NMR transverse relaxation for pore size distribution estimation in porous media","authors":"S. Morales-Chávez ,&nbsp;M.A. Valdez-Grijalva ,&nbsp;M.A. Díaz-Viera ,&nbsp;E. Lucas-Oliveira ,&nbsp;T.J. Bonagamba","doi":"10.1016/j.jmr.2025.107922","DOIUrl":"10.1016/j.jmr.2025.107922","url":null,"abstract":"<div><div>Nuclear Magnetic Resonance (NMR) is a widely useful technique for studying porous media. Of particular interest are transverse relaxation times (<span><math><msub><mrow><mi>T</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>), which are often associated with pore size when surface relaxation is the dominant mechanism. Under specific physical assumptions, a distribution of <span><math><msub><mrow><mi>T</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> can be used to infer the pore size distribution (PSD). However, in real porous rocks, a combination of diffusion and relaxation mechanisms complicates this interpretation. Despite recent advancements in industrial applications, conventional models frequently rely on simplifying assumptions, particularly when pore size is considered in the fast diffusion regime. This results in the neglect of transverse bulk relaxation (<span><math><msub><mrow><mi>T</mi></mrow><mrow><mn>2</mn><mi>B</mi></mrow></msub></math></span>) effects, leading to underestimations of pore sizes. To address this, numerical methods, particularly the Finite Element Method (FEM), offer flexibility in modeling symmetric geometries while significantly reducing computational complexity. This paper presents a mathematical NMR model and numerical implementation based on FEM to simulate transverse magnetization signals for a PSD, validated with semi-analytical solutions and applied to synthetic and real samples, such as Berea sandstone. Additionally, a change of variable in the Inverse Laplace Transform (ILT) model is introduced for the direct PSD estimation, demonstrating a strong agreement between experimental and simulated data.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"379 ","pages":"Article 107922"},"PeriodicalIF":2.0,"publicationDate":"2025-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144588622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Circuit design for broadband decoupling in multi-coil multi-nuclear applications","authors":"Joseph Busher ,&nbsp;Edith Touchet-Valle ,&nbsp;Jacob Degitz ,&nbsp;Mary P. McDougall","doi":"10.1016/j.jmr.2025.107924","DOIUrl":"10.1016/j.jmr.2025.107924","url":null,"abstract":"<div><div>The wealth of information available from multinuclear magnetic resonance imaging and spectroscopy is largely untapped in the clinical setting. This is due to a multitude of challenges in the pipeline ranging from acquisition strategies, hardware design, processing, and interpretation/analysis. As a small part of addressing these challenges, this work presents a straightforward approach for broadband decoupling between coils. This circuit was created with the implementation of a series PIN diode and was evaluated on the bench and experimentally for ¹H, ³¹P and ²³Na at 3 T. Individual coils were single-tuned with this decoupling network and stacked to enable a switched triple-tuned coil. These coils were evaluated in various purposefully coupled configurations and compared to a narrowband trap active detuning network to demonstrate potential modularity of this design. Narrowband trapped coils showed drops in SNR when combined with other coils, presumably due to coupling between receiver elements tuned to different frequencies. This broadband decoupling behavior was shown to be independent of positioning through coils oriented to be nearly perfectly geometrically coupled and the addition of a three-element array of the same size. This configuration was validated on a post-mortem pig to verify the losses of the network did not prohibit its use for preclinical imaging and spectroscopy applications. Although losses were incurred as a result of the broadband decoupling network, it enabled a modular design that can be adapted to a given study without significant compromise of the signal integrity and could eliminate the need for certain custom coils for multi-nuclear studies.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"378 ","pages":"Article 107924"},"PeriodicalIF":2.0,"publicationDate":"2025-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144548630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Probe design for high sensitivity proton-detected solid-state NMR","authors":"Collin G. Borcik ,&nbsp;Lauren E. Price ,&nbsp;John P. Heinrich ,&nbsp;John A. Stringer ,&nbsp;Chad M. Rienstra","doi":"10.1016/j.jmr.2025.107919","DOIUrl":"10.1016/j.jmr.2025.107919","url":null,"abstract":"<div><div>Proton (¹H) detection methodologies in solid-state NMR (SSNMR) have revolutionized the field allowing for probing of new frontiers in determining the structure and dynamics within biological systems and materials. While approaches that maximally leverage the high gyromagnetic ratio of ¹H detection have enhanced sensitivity and resolution of SSNMR experiments, the radiofrequency (rf) circuit of magic-angle spinning (MAS) probes is not well optimized for ¹H detection, limiting the overall signal-to-noise ratio (SNR). Rather, SSNMR probes have historically been optimized for lower gamma nuclei such as ¹³C and below. Here we present a design with an inner coil for proton (¹H) to maximize ¹H sensitivity. Optimizing the ¹H channel resulted in a 1.33–2-fold increase in SNR with ¹H detection in a one-dimensional experiment. An outer coil is tuned to the ¹³C and ¹⁵N frequencies, with excellent B₁ homogeneity on all three channels. Using this design, we find that the sensitivity scales better than the theoretical expectations from 600 MHz to 750 MHz, due to a combination of the improved rf efficiency and B₁ homogeneity. We also demonstrate these improvements on a model protein system (GB1) with a 4D experiment collected in less than a day.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"378 ","pages":"Article 107919"},"PeriodicalIF":2.0,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144297133","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design and characterization of a tunable open TE011 resonator for Q-band pulse EPR experiments","authors":"Kyle Jorgensen,&nbsp;Alexey Silakov","doi":"10.1016/j.jmr.2025.107921","DOIUrl":"10.1016/j.jmr.2025.107921","url":null,"abstract":"<div><div>Electron Paramagnetic Resonance (EPR) is an important technique for the investigation of the structure and function of metalloproteins and enzymes. The variety of questions in this line of research requires versatile instrumentation. In this work, we explored the utility of the open resonator concept for a general-use highly tunable TE₀₁₁ resonator design at Q-band frequencies (≈ 34 GHz). Using proof-of-concept calculations, we establish a viable range of critical parameters compatible with the desired instrument specifications. We then present the resonator design, targeting ease of execution and handling. Experimental characterization of the built resonator shows high tunability. Specifically, we show that the resonator can be critically coupled and overcoupled with a three-fold change in the bandwidth using a matching short. We also show that the resonator can be incorporated with frequency tuning by means of movable axial plungers, allowing it to work with a wide range of samples using relatively narrow-bandwidth microwave instrumentation. Furthermore, because of its high tunability, the resonator is very tolerant of manufacturing imperfections, which makes it affordable and easy to execute with minimal tooling. We also discuss the long-term use of the resonator in our research, highlighting its versatility.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"378 ","pages":"Article 107921"},"PeriodicalIF":2.0,"publicationDate":"2025-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144270832","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reduction of radiofrequency induced implant heating via flexible metasurface shielding at 7 T","authors":"Paul S. Jacobs ,&nbsp;Wyger M. Brink ,&nbsp;Pradnya Narvekar ,&nbsp;Neil E. Wilson ,&nbsp;Anshuman Swain ,&nbsp;Neeraj Panchal ,&nbsp;Samir Mehta ,&nbsp;Mark A. Elliott ,&nbsp;Ravinder Reddy","doi":"10.1016/j.jmr.2025.107918","DOIUrl":"10.1016/j.jmr.2025.107918","url":null,"abstract":"<div><div>Passive implanted devices are commonly contraindicated at ultra-high field MRI due to the risk of radiofrequency heating. Mitigation of this risk has come in many forms, such as modifying implant materials or creating novel radiofrequency coils. These methods require substantial involvement from manufacturers and may not benefit patients with existing implants. In this study, a tailored metasurface design is demonstrated to improve implant safety at 7 T by shielding the local B₁⁺ field. A prototype metasurface was designed and implemented with a unit cell size of 15 mm using discrete capacitors of 30 pF values. Phantom and human body model simulations were used to validate differences in the SAR distribution with and without the metasurface. Fiber optic temperature probes were used to measure temperature increase across two representative orthopedic screws placed inside a tissue mimicking phantom during a high-SAR sequence. Phantom and in-vivo imaging were performed to assess the metasurface effect on image quality. With the metasurface, an average maximum temperature decrease of 0.50 °C or 34.9 % near the implant was observed. RF field simulations yielded similar decreases in SAR for the phantom (40.7 %) and substantial decreases for the in-vivo leg model (97 %). Phantom image SNR showed a global 8.5 % decrease with the metasurface while in-vivo images showed a 4.8 % decrease in SNR, with the region in its immediate vicinity experiencing substantial signal drop. These results demonstrate the feasibility of a metasurface designed to substantially reduce local RF induced heating with only minor degradation of image quality. Future work will focus on refinement of the metasurface design and further in-vivo testing.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"377 ","pages":"Article 107918"},"PeriodicalIF":2.0,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144212752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Finite element modeling of Rb-129Xe spin-exchange optical pumping and optimized Rb source distribution","authors":"Jimmy E. Ball,&nbsp;Jim M. Wild,&nbsp;Graham Norquay","doi":"10.1016/j.jmr.2025.107889","DOIUrl":"10.1016/j.jmr.2025.107889","url":null,"abstract":"<div><div>Rubidium (Rb) vapor density (<span><math><mrow><mo>[</mo><mtext>Rb</mtext><mo>]</mo></mrow></math></span>) is a key parameter in xenon-129 polarization (<span><math><msub><mrow><mi>P</mi></mrow><mrow><mtext>Xe</mtext></mrow></msub></math></span>) build up in spin-exchange optical pumping. In practice, <span><math><mrow><mo>[</mo><mtext>Rb</mtext><mo>]</mo></mrow></math></span> within the cell often falls below saturation levels and is spatially heterogeneous leading to system underperformance. In this study, finite element modeling was performed to investigate the role of Rb source distribution in heterogeneous in-cell <span><math><mrow><mo>[</mo><mtext>Rb</mtext><mo>]</mo></mrow></math></span>, and to optimize a Rb presaturator to achieve homogeneous <span><math><mrow><mo>[</mo><mtext>Rb</mtext><mo>]</mo></mrow></math></span> and reduce the flow rate dependence of <span><math><mrow><mo>[</mo><mtext>Rb</mtext><mo>]</mo></mrow></math></span>. Lower than expected <span><math><msub><mrow><mi>P</mi></mrow><mrow><mtext>Xe</mtext></mrow></msub></math></span> in previous iterations of our polarizer can be attributed to sub-saturation <span><math><mrow><mo>[</mo><mtext>Rb</mtext><mo>]</mo></mrow></math></span> due to the small surface area of the Rb source in the main cell body and the absence of upstream Rb vapor presaturation, leading to lower than desired <span><math><msub><mrow><mi>P</mi></mrow><mrow><mtext>Xe</mtext></mrow></msub></math></span>. We found that increasing the surface area of the Rb source in the main cell body does not effectively reduce <span><math><mrow><mo>[</mo><mtext>Rb</mtext><mo>]</mo></mrow></math></span> heterogeneity. Instead, achieving a more uniform distribution of <span><math><mrow><mo>[</mo><mtext>Rb</mtext><mo>]</mo></mrow></math></span> necessitates the use of a sufficiently long presaturator at a given gas flow rate, increasing <span><math><msub><mrow><mi>P</mi></mrow><mrow><mtext>Xe</mtext></mrow></msub></math></span>. We also report discrepancy between modeled and experimentally measured laser absorption, highlighting limitations of the existing optical pumping model and suggesting directions for future model revisions and the investigation of currently unexplored areas.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"377 ","pages":"Article 107889"},"PeriodicalIF":2.0,"publicationDate":"2025-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144178273","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Probing rare and short-lived conformational states in nucleic acids using off-resonance carbonyl and guanidino carbon R1ρ relaxation dispersion","authors":"Supriya Pratihar ,&nbsp;Yeongjoon Lee ,&nbsp;Ainan Geng ,&nbsp;Shibani Bhattacharya ,&nbsp;Hashim M. Al-Hashimi","doi":"10.1016/j.jmr.2025.107910","DOIUrl":"10.1016/j.jmr.2025.107910","url":null,"abstract":"<div><div>Chemical exchange-based NMR techniques provide powerful approaches for characterizing lowly-populated and short-lived conformational states in nucleic acids. Among possible probes, the nucleobase carbonyl and guanidino carbons stand out due to the sensitivity of their chemical shifts to hydrogen bonding and keto–enol tautomerization. However, chemical exchange measurements targeting these carbon nuclei have not yet been reported in studies of nucleic acids. Here, we present an experiment for measuring off-resonance <em>R</em>_1ρ relaxation dispersion for guanine-C2, guanine-C6, thymine/uracil-C2, and thymine/uracil-C4 carbons in uniformly ¹³C/¹⁵N labeled nucleic acids. We demonstrate the utility of the experiment by characterizing chemical exchange in a G•T mismatch in duplex DNA between a dominant wobble conformation and two lowly-populated, short-lived, and rapidly interconverting Watson–Crick-like tautomeric states (G^enol•T ⇌ G•T^enol) implicated in DNA replicative errors. The population and exchange rate deduced from the guanine-C6, guanine-C2, and thymine-C4 off-resonance <em>R</em>_1ρ relaxation dispersion profiles were in excellent agreement with counterparts obtained from <em>R</em>_1ρ measurements on proton-bound carbon and nitrogen nuclei. The carbon chemical shifts of the minor state were downfield shifted relative to the wobble ground state, consistent with (G)C6 = O···HO-C4(T^enol) and (G^enol)C6-OH···O=C4(T) hydrogen bonding in the Watson-Crick-like tautomeric state. As a second application, we did not detect any exchange contribution to uracil-C2 and uracil-C4 <em>R</em>_1ρ profiles measured for a U·U mismatch in RNA, consistent with isomerization between two alternative wobble conformations occurring on the sub-microsecond timescale. These results establish carbonyl and guanidino carbons as valuable probes for chemical exchange measurements of micro-to-millisecond motions in nucleic acids.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"377 ","pages":"Article 107910"},"PeriodicalIF":2.0,"publicationDate":"2025-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144204790","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of insufficient 31P pulse amplitudes on 13C-detected 31P13C rotational-echo double-resonance measurements in solid state NMR","authors":"Motahareh G. Larimi,&nbsp;Robert Tycko","doi":"10.1016/j.jmr.2025.107908","DOIUrl":"10.1016/j.jmr.2025.107908","url":null,"abstract":"<div><div>We investigate the effects of insufficient ³¹P pulse amplitudes on ¹³C-detected ³¹P<img>¹³C Rotational-Echo Double-Resonance (REDOR) measurements in a 17.5 T magnetic field. Experimental REDOR data on two compounds show that normalized REDOR difference signals <span><math><mi>Δ</mi><mi>S</mi><mo>/</mo><msub><mi>S</mi><mn>0</mn></msub></math></span> are suppressed when the amplitudes of ³¹P π pulse trains are not very large compared with the ³¹P chemical shift anisotropies. This behavior is explained theoretically by an analysis of the effects of imperfections in π pulse rotations due to the orientation-dependent and time-dependent resonance offsets under magic-angle spinning in REDOR measurements. We show that effects of the same pulse imperfections can be observed directly by measurements of an effective relaxation time <span><math><msup><msub><mi>T</mi><mn>1</mn></msub><mi>eff</mi></msup></math></span> for longitudinal ³¹P spin polarization under identical π pulse trains.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"377 ","pages":"Article 107908"},"PeriodicalIF":2.0,"publicationDate":"2025-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144212751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}