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Gao M, Luo S, Zhu L, Xiao L, Liu H, Liao G, Lv X, Chen H, Wang Y. Easy-to-implement passive shimming approach of Halbach magnet for low-field NMR measurement. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2025; 376:107887. [PMID: 40381246 DOI: 10.1016/j.jmr.2025.107887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2025] [Revised: 04/02/2025] [Accepted: 04/21/2025] [Indexed: 05/20/2025]
Abstract
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.
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Affiliation(s)
- Mengjuan Gao
- College of Artificial Intelligence, China University of Petroleum, Beijing 102249, China
| | - Sihui Luo
- College of Carbon Neutral Energy, China University of Petroleum, Beijing 102249, China.
| | - Lin Zhu
- College of Artificial Intelligence, China University of Petroleum, Beijing 102249, China
| | - Lizhi Xiao
- College of Artificial Intelligence, China University of Petroleum, Beijing 102249, China; College of Geophysics, China University of Petroleum, Beijing 102249, China
| | - Huabing Liu
- Beijing Limecho Technology Co., Ltd, Beijing 102200, China
| | - Guangzhi Liao
- College of Artificial Intelligence, China University of Petroleum, Beijing 102249, China; College of Geophysics, China University of Petroleum, Beijing 102249, China
| | - Xinman Lv
- College of Geophysics, China University of Petroleum, Beijing 102249, China
| | - Hao Chen
- College of Geophysics, China University of Petroleum, Beijing 102249, China
| | - Yi Wang
- College of Geophysics, China University of Petroleum, Beijing 102249, China
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Zhou Z, Duan X, Yu Y, Ma L, Moreno A, Xia Y, Chen L, Ye S, Cong R. Recent Advances and Applications of NMR Techniques in Plastic Characterizations. Anal Chem 2025; 97:5847-5865. [PMID: 40029001 DOI: 10.1021/acs.analchem.4c05230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/05/2025]
Affiliation(s)
- Zhe Zhou
- National Institute of Clean-and-Low-Carbon Energy, Beijing 102209, China
| | - Xuelei Duan
- National Institute of Clean-and-Low-Carbon Energy, Beijing 102209, China
| | - Yue Yu
- National Institute of Clean-and-Low-Carbon Energy, Beijing 102209, China
| | - Linge Ma
- National Institute of Clean-and-Low-Carbon Energy, Beijing 102209, China
| | - Aitor Moreno
- Bruker Switzerland AG, CH-8117 Fällanden, Switzerland
| | - Youlin Xia
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, United States
| | - Linfeng Chen
- National Institute of Clean-and-Low-Carbon Energy, Beijing 102209, China
| | - Shan Ye
- National Institute of Clean-and-Low-Carbon Energy, Beijing 102209, China
| | - Rongjuan Cong
- National Institute of Clean-and-Low-Carbon Energy, Beijing 102209, China
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Zhang Y, Zhang J, Wang Z, Fan L, Chen Y. Effect of Rice Protein on the Gelatinization and Retrogradation of Rice Starch with Different Moisture Content. Foods 2024; 13:3734. [PMID: 39682805 DOI: 10.3390/foods13233734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2024] [Revised: 11/19/2024] [Accepted: 11/20/2024] [Indexed: 12/18/2024] Open
Abstract
Rice protein and moisture content are pivotal in the gelatinization and retrogradation processes of rice starch. This study aimed to explore the influence of rice protein on these processes by preparing rice starch gels with varying moisture levels and incorporating rice protein. At a high moisture content of 1:6, rice protein exhibited a minimal effect on the gelatinization properties of rice starch but significantly retarded the retrogradation of the starch gel. At intermediate moisture levels of 1:4 and 1:2, the rice starch gels showed pronounced retrogradation. However, rice protein was effective in inhibiting this retrogradation at a 1:4 moisture content, while its inhibitory effect diminished at a 1:2 moisture content. Under low moisture conditions of 1:1, the gelatinization of rice starch was markedly constrained by the limited water availability, but rice protein mitigated this constraint. Conversely, at this moisture level, rice protein promoted the retrogradation of the rice starch gel during the retrogradation process. The findings of this study offer a theoretical foundation that could inform the production of rice-based products.
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Affiliation(s)
- Yifu Zhang
- College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin 300457, China
| | - Jiawang Zhang
- College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin 300457, China
| | - Zeyu Wang
- College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin 300457, China
| | - Longxiang Fan
- College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin 300457, China
| | - Ye Chen
- College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin 300457, China
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Chen B, Fang Z, Zhang Y, Guan X, Lin E, Feng H, Zeng Y, Cai S, Yang Y, Huang Y, Chen Z. Two-Dimensional Laplace NMR Reconstruction through Deep Learning Enhancement. J Am Chem Soc 2024; 146:21591-21599. [PMID: 39046081 DOI: 10.1021/jacs.4c05211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/25/2024]
Abstract
Laplace NMR is a powerful tool for studying molecular dynamics and spin interactions, providing diffusion and relaxation information that complements Fourier NMR used for composition determination and structure elucidation. However, Laplace NMR demands sophisticated signal processing algorithms such as inverse Laplace transform (ILT). Due to the inherently ill-posed nature of ILT problems, it is generally challenging to perform satisfactory Laplace NMR processing and reconstruction, particularly for two-dimensional Laplace NMR. Herein, we propose a proof-of-concept approach that blends a physics-informed strategy with data-driven deep learning for two-dimensional Laplace NMR reconstruction. This approach integrates prior knowledge of mathematical and physical laws governing multidimensional decay signals by constructing a forward process model to simulate relationships among different decay factors. Benefiting from a noniterative neural network algorithm that automatically acquires prior information from synthetic data during training, this approach avoids tedious parameter tuning and enhances user friendliness. Experimental results demonstrate the practical effectiveness of this approach. As an advanced and impactful technique, this approach brings a fresh perspective to multidimensional Laplace NMR inversion.
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Affiliation(s)
- Bo Chen
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen, Fujian 361005, China
| | - Ze Fang
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen, Fujian 361005, China
| | - Yuebin Zhang
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen, Fujian 361005, China
| | - Xun Guan
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen, Fujian 361005, China
| | - Enping Lin
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen, Fujian 361005, China
| | - Hai Feng
- College of Artificial Intelligence, Application Technology Research Center of Artificial Intelligence, Xiamen City University, Xiamen, Fujian 361008, China
| | - Yunsong Zeng
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen, Fujian 361005, China
| | - Shuhui Cai
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen, Fujian 361005, China
| | - Yu Yang
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen, Fujian 361005, China
| | - Yuqing Huang
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen, Fujian 361005, China
| | - Zhong Chen
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen, Fujian 361005, China
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Tao W, Yu W, Zou X, Chen W. Machine learning assisted interpretation of 2D solid-state nuclear magnetic resonance spectra. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2023; 353:107492. [PMID: 37302236 DOI: 10.1016/j.jmr.2023.107492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 05/22/2023] [Accepted: 05/25/2023] [Indexed: 06/13/2023]
Abstract
A machine learning methodology using deep neural network (DNN) for interpreting multidimensional solid-state nuclear magnetic resonance (SSNMR) of various synthetic and natural polymers is presented. The separated local field (SLF) SSNMR which correlates local well-defined heteronuclear dipolar with the tensor orientation of the chemical shift anisotropy (CSA) of spin in the solid state can provide valuable structure and molecular dynamics information of synthetic and biopolymers. Compared with the traditional linear least-square fitting, the proposed DNN-based methodology can efficiently and accurately determine the tensor orientation of CSA of both 13C and 15N in all four samples. The method achieves prediction precisions of the Euler angles with < ±5° and is characterized by low training costs and high efficiency (<1 s). The feasibility and robustness of the DNN-based analysis methodology are confirmed by comparison to reported-literature values. This strategy is expected to aid in the interpretation of complex multidimensional NMR spectra of complicated polymer system.
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Affiliation(s)
- Wei Tao
- National Synchrotron Radiation Laboratory, Anhui Provincial Engineering Laboratory of Advanced Functional Polymer Film, CAS Key Laboratory of Soft Matter Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Wancheng Yu
- National Synchrotron Radiation Laboratory, Anhui Provincial Engineering Laboratory of Advanced Functional Polymer Film, CAS Key Laboratory of Soft Matter Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Xiangyu Zou
- Department of Accelerator Science and Engineering Physics, School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230026, China
| | - Wei Chen
- National Synchrotron Radiation Laboratory, Anhui Provincial Engineering Laboratory of Advanced Functional Polymer Film, CAS Key Laboratory of Soft Matter Chemistry, University of Science and Technology of China, Hefei 230026, China; Department of Accelerator Science and Engineering Physics, School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230026, China.
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