Journal of magnetic resonance最新文献

{"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}

{"title":"Diamond rotors for high magic angle spinning frequencies","authors":"Lauren Schaffer ,&nbsp;David Preiss ,&nbsp;Ravi Shankar Palani ,&nbsp;Nicholas Wiesner ,&nbsp;Jiaming Liu ,&nbsp;Samuel Strymish ,&nbsp;Salima Bahri ,&nbsp;Sara Linse ,&nbsp;Neil Gershenfeld ,&nbsp;Robert G. Griffin","doi":"10.1016/j.jmr.2025.107909","DOIUrl":"10.1016/j.jmr.2025.107909","url":null,"abstract":"<div><div>Magic Angle Spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy is limited in spectral resolution by the spinning frequency of rotors that hold the analyte. Traditional yttria-stabilized zirconia (YSZ) rotors have mechanical constraints that typically limit spinning frequencies of 0.7 mm rotors to ω_r/2π ∼ 110 kHz. These frequencies are not sufficient to achieve resolution comparable to that of solution NMR, which theoretically requires ω_r/2π &gt; 300 kHz. Building upon prior work that utilized rotary-assisted drilling, we present significant advances in diamond rotor fabrication using a high precision lathe and a centerless laser machining fixture that achieves improved concentricity of the rotor outer and inner diameters and spinning stability. The new crop of diamond rotors, which interface with the Bruker MAS 3 spinning system equivalently or better than commercial rotors, were spun using automatic 0.7 mm profiles. Furthermore, diamond rotors can be emptied and repacked, and we describe a set of 3D-printed centrifuge tools for efficient execution of this process. We evaluate chemical vapor deposition (CVD) versus high-pressure high-temperature (HPHT) diamonds as rotor material and find HPHT preferable. Extended spin stability tests and multidimensional NMR spectra of Aβ₁_–₄₀ demonstrate the robustness and usability of these rotors. These advances pave the way for higher frequency spinning with helium gas in the future, enabling transformative improvements in MAS NMR for biological and material sciences.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"379 ","pages":"Article 107909"},"PeriodicalIF":2.0,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144570748","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":"Evaluating the effect of 1H decoupling on 19F longitudinal relaxation and signal line shape in 5-Fluorotryptophan","authors":"Yuki Toyama ,&nbsp;Koh Takeuchi ,&nbsp;Ichio Shimada","doi":"10.1016/j.jmr.2025.107899","DOIUrl":"10.1016/j.jmr.2025.107899","url":null,"abstract":"<div><div>Fluorine 19 (¹⁹F) in aromatic rings serves as a useful spin probe for studying the structure, dynamics, and intermolecular interactions of biomolecules and small-molecule ligands. Although ¹⁹F NMR involving aromatic ¹⁹F probes has a number of applications, quantitative relaxation analyses of these probes remain challenging due to the complexity of ¹H-¹⁹F spin interaction networks. In this study, we investigated ¹H-¹⁹F spin interactions in the 5-fluorotryptophan system, focusing on the effects of ¹H decoupling on ¹⁹F relaxation properties and line shape. We demonstrate that ¹H decoupling significantly slows down the ¹⁹F magnetization recovery process, leading to reduced sensitivity particularly in large proteins. In addition, ¹H decoupling effectively eliminates cross-correlations between ¹⁹F chemical shift anisotropy and ¹H-¹⁹F dipole-dipole interactions, resolving the asymmetric line shape of the aromatic ¹⁹F signal. Through experimental and theoretical analyses of the ¹H-coupled ¹⁹F spin system, we propose a model that explains these relaxation behaviors. Our results offer practical guidelines for optimizing ¹H decoupling schemes in aromatic ¹⁹F probes, thereby expanding the utility of ¹⁹F NMR.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"377 ","pages":"Article 107899"},"PeriodicalIF":2.0,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144146815","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":"PyEPRI: A CPU & GPU compatible python package for electron paramagnetic resonance imaging","authors":"Rémy Abergel ,&nbsp;Sylvain Durand ,&nbsp;Yves-Michel Frapart","doi":"10.1016/j.jmr.2025.107891","DOIUrl":"10.1016/j.jmr.2025.107891","url":null,"abstract":"<div><div>This work presents the PyEPRI package, an open-source Python package for Electron Paramagnetic Resonance Imaging. The PyEPRI package implements low-level operators, like projection and backprojection, involved in Electron Paramagnetic Resonance (EPR) and also high-level advanced algorithms, like total variation based EPR image reconstruction, for end-users. The package is fully implemented in Python and provides both CPU and GPU computation capabilities, through the libraries Numpy, PyTorch and Cupy. This package comes with a detailed documentation, including precise mathematical definitions and many reproducible demonstration examples and tutorials, making it easy for users with no particular expertise on coding image processing algorithms to get started. This package is also highly modular and only relies on standard data types, as such, it can also be easily used by advanced users to develop new algorithms while benefiting from an optimized computing environment and some rigorously tested operators.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"376 ","pages":"Article 107891"},"PeriodicalIF":2.0,"publicationDate":"2025-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144116455","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":"Easy-to-implement passive shimming approach of Halbach magnet for low-field NMR measurement","authors":"Mengjuan Gao ,&nbsp;Sihui Luo ,&nbsp;Lin Zhu ,&nbsp;Lizhi Xiao ,&nbsp;Huabing Liu ,&nbsp;Guangzhi Liao ,&nbsp;Xinman Lv ,&nbsp;Hao Chen ,&nbsp;Yi Wang","doi":"10.1016/j.jmr.2025.107887","DOIUrl":"10.1016/j.jmr.2025.107887","url":null,"abstract":"<div><div>Halbach magnets have been widely employed to NMR instruments due to their low weight, low cost, and minimal leakage of magnetic field. However, field inhomogeneity remains challenge due to discrete magnet rings and manufacturing deviations of the magnetic elements. This paper aims to address this limitation through an effective passive shimming approach, which is considered the first step toward constructing high-homogeneity magnets because of its non-powered and inherently stable characteristics. We focus on the transverse dipole field generated by Halbach magnets and develop an easily implementable linear programming-genetic algorithm (LP-GA) hybrid optimization approach for passive shimming. Our methodology first employs an equivalent magnetic dipole model to calculate the sensitivity matrix of the shim pieces in the Region of Interest (ROI). Then, the LP-GA hybrid optimization algorithm determines the optimal position, number, and thickness of the shim pieces. By combining shim pieces of three different thicknesses (1 mm, 1.5 mm, and 2 mm), we significantly reduce the field inhomogeneity of a 48 mT Halbach magnet system. The effectiveness of our approach is validated through NMR measurements using water samples with copper sulfate at different concentrations, demonstrating an improvement in field homogeneity from approximately 1229 ppm to 320 ppm. The experimental results confirm that the proposed approach effectively enhances magnetic field homogeneity of low-field Halbach magnet systems and could be applied to shimming various Halbach-like magnet arrays.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"376 ","pages":"Article 107887"},"PeriodicalIF":2.0,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144069153","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}