Recognition of chiral molecules is critical for the chemical and pharmaceutical industries. Three kinds of urea containing chiral centers (L-Phe-U, L-Ala-U and L-Val-U) were synthesized as chiral solvating agents (CSAs) to identify chiral organic carboxylic acids with different substituents, whose chiral anion recognition properties were further examined by NMR spectroscopy. In the presence of 4-dimethylaminopyridine (DMAP), enantiomeric signals of the benzylic C-H protons of mandelic acid were observed when mixed with L-Phe-U. The ΔΔδ values of the C_αH signals ranged from 2.4 to 16.0 Hz, and the enantiomer excess (ee) value of RS-rac-mandelic acid (rac-MA) can be determined accurately. It was found that the phenyl group contained in chiral solvating agents and the groups connected to the chiral carbon center of substrates would affect the separation of enantiomeric signals. Moreover, DOSY spectra reveal that the diffusion coefficients of rac-MA enantiomers differ in the chiral solvating agents, providing insights into the dynamics of chiral recognition.

The immunosuppressive tumor microenvironment (ITME) poses a significant challenge to anti-tumor immunotherapy. Our research develops a novel nanoenzyme based on Mn²⁺ and endogenous hemin. The nanozyme possesses superior multi-enzymatic activities, which could significantly reverse the ITME and trigger a vigorous anti-tumor immune response, thereby inhibiting both tumor growth and metastasis when used in conjunction with immune checkpoint inhibitor (ICI), αPD-L1. Moreover, it functions as a magnetic resonance imaging (MRI) contrast agent for the visualization of tumors and the trace of nanoenzyme.

Magnetic resonance fingerprinting (MRF) has shown great potential for the quantitative assessment of tissue susceptibility across diverse diseases. However, reconstructing high-quality temporal images from highly undersampled data and thus achieving high-precision quantitative imaging remains a primary challenge in MRF. In this paper, we propose a novel MRF reconstruction framework leveraging manifold structured data priors. This approach models fingerprint signals and tissue quantitative parameters as data points residing on manifolds, and reveals the intrinsic topological consistency between the fingerprint manifold and the parameter manifold. Based on this key observation, we introduce a manifold structured data regularization constraint for MRF reconstruction. By enforcing structural consistency between the fingerprint manifold and the parameter manifold during reconstruction, the proposed constraint effectively improves reconstruction quality. Furthermore, to fully exploit the inherent data correlations, we integrate a locally low-rank prior into our reconstruction framework, which further enhances reconstruction performance. Experimental results demonstrate that the proposed method achieves notable enhancement in reconstruction quality while significantly reducing computational time compared to existing approaches, highlighting its potential for clinical translation in high-quality MRF imaging.

Magnetic resonance imaging (MRI) demonstrates significant value in the diagnosis of fetal skeletal abnormalities during the second trimester. Current clinical practice confronts challenges in improving diagnostic accuracy and assessing the impact of diagnosis on pregnancy outcomes, while conventional prenatal B-scan ultrasonography has limitations in diagnostic efficacy. From January 2021 to January 2024, this study analyzed the second-trimester imaging reports of 58 cases who were confirmed with fetal skeletal abnormalities after labor induction or delivery, revealing MRI's superior diagnostic performance compared to B-scan ultrasonography in the detection rate of fetal skeletal abnormalities, the diagnostic coincidence rate of induced abortion recommendations and overall excellent image quality rate. The diagnostic value of MRI for detecting fetal skeletal abnormalities in the second trimester makes it a reliable technique to provide fetal skeletal information for pregnant women and their families, which is conducive to pregnancy outcomes and healthy birth, and has broad clinical application prospects.

In recent years, the exploration and development of shale oil and gas have expanded significantly, accompanied by numerous challenges. Porosity is a fundamental parameter for shale reservoir evaluation and reserve estimation, providing essential data for determining sweet spots and formulating development plans. Low-field nuclear magnetic resonance (LF-NMR) technology has unique non-invasive, non-destructive characteristics and has become a crucial method for shale porosity measurement. However, shale has substantially different nuclear magnetic resonance (NMR) response mechanisms from that of conventional sandstone and carbonate reservoir rocks. Furthermore, improper experimental parameters or inversion process can lead to errors or even faults in the measurement of shale porosity by NMR. In this paper, T₁-T₂ correlation is adopted to qualitatively identify hydrogen-containing components in dry and saturated shale. Based on the principle that NMR signal is proportional to the number of spin protons under uniform static magnetic field and constant temperature field, an experimental method is proposed to directly measure the shale porosity. This method calibrates with standard water sample, then compares the first amplitude of the NMR free induction decay (FID) signal between water-saturated and dry shale. The experimental results show that the NMR porosity obtained through this method is in good agreement with the weight porosity, and the influence of background signal from hydrogen-containing matrix components in shale is eliminated.

In the field of magnetic resonance imaging (MRI), multi-source emission can improve the uniformity of radio frequency (RF) magnetic field and the quality of MRI images. In this paper, we propose a portable MRI multi-source RF pulse generator design based on the Zynq 7000 SoC all programmable system-on-chip. The design consists of a host computer software with fully open pulse sequence parameters and a fully digitalized, highly integrated, dual credit card-sized hardware board, which outputs multiple RF pulse signals with independently adjustable waveform, frequency, phase, and amplitude in parallel. The hardware description language Verilog is used to build AXI DDS (advanced eXtensible interface direct digital synthesizer) and multiplier circuits inside the FPGA (field programmable gate array) to realize the functions of generating multiple RF pulse signals and signal modulation. The experimental results show that the design can correctly transmit four MRI RF pulse signals, providing a fully digital, reconfigurable, compact, and feasible solution for developing a portable magnetic resonance multi-source RF pulse generator.

The detection of microsamples holds extensive application demands in fields such as environmental monitoring, biological sciences, and medicine. When conventional magnetic resonance probes are used to detect microsamples, the smaller filling factors lead to reduced signal-to-noise ratios (SNR) in magnetic resonance detection. Using microcoils comparable in size to the microsamples can significantly improve detection sensitivity and enhance SNR. Furthermore, due to the growing demand for broadband detection, there is a desire to reduce experimental steps during sample analysis and shorten detection times. However, currently available commercial probes are not designed for microsample detection and are relatively too complex to meet the requirements for efficient and convenient applications. To address these issues, this study designed a multilayer solenoid microcoil with excellent field uniformity, low inductance, and resistance. The coil was fabricated using printed circuit board (PCB) technology and tested on a 1.5 T MRI system magnet equipped with a self-developed spectrometer and broadband RF front end, where multiple nuclei (¹H, ²H, ⁷Li, ¹⁹F) were detected in 250 nL samples, demonstrating broadband capability and high sensitivity. The results highlight its potential for efficient and versatile microsample analysis.

Signal-to-noise ratio (SNR) is a key parameter governing signal quality in benchtop MRS spectrometers, where quadrature circularly polarized coils offer an effective means to enhance SNR. However, the confined space within the compact magnets of desktop systems poses challenges for implementing such coils—a strategy previously unattempted in this domain. Leveraging a self-developed desktop MRS platform, this study designed and fabricated a flexible printed circuit-based transceiver-integrated circularly polarized coil system, comprising orthogonally arranged saddle and Helmholtz coils. The coil geometry was optimized through Ansys Maxwell simulations, and experimental validation using CuSO₄ solution demonstrated SNR improvements of 28.78% and 29.21% over single-channel saddle and Helmholtz coils, respectively, alongside a 37.5% reduction in reflected power. These results confirm the viability of circularly polarized coils for advancing desktop MRS probe performance.

Nuclear magnetic resonance (NMR) technology enables the acquisition of multi-scale molecular dynamics by characterizing the variation of relaxation times under different magnetic field conditions, thereby offering a critical detection methodology for petroleum logging research. To minimize magnetic field gradients induced by susceptibility differences between solid and liquid phases, low-field NMR systems are predominantly employed in petroleum logging applications. However, the inherent limitations of reduced sensitivity in low-field environments present significant challenges for applied studies, necessitating stringent noise performance specifications for receiving circuitry. As the primary stage of the signal reception chain, the preamplifier’s noise characteristics fundamentally determine the signal-to-noise ratio (SNR) of NMR measurements. To address the requirements of low-field NMR, this paper adopts a cascade topology combining a common-emitter and common-collector two-stage amplification circuit, and integrates negative feedback to optimize input broadband matching and noise figure. Consequently, a high-gain, low-noise broadband preamplifier has been developed. The implemented preamplifier demonstrates excellent performance parameters: NF≤0.73 dB, gain≥31 dB, gain flatness≤0.35 dB, and equivalent input voltage noise density≤0.45 nV/$\sqrt{\text{Hz}}$ across the 10~30 MHz frequency band. Integrated into an NMR spectrometer system, the amplifier demonstrated favorable ¹H NMR signal SNR under 0.5 T, 0.35 T, and 0.25 T magnetic field conditions. These results indicate that the developed low-noise amplifier provides critical technical support for advancing low-field NMR applications.

Magnetic resonance imaging (MRI), as a non-invasive, high-resolution medical imaging technology, is a powerful tool for clinical disease diagnosis. Current MRI systems are advancing towards higher magnetic field strength. High-field (HF) and ultra-high-field (UHF) MRI have demonstrated substantial advantages in clinical diagnosis and emerging cutting-edge imaging technologies, making them a focus of global competition. HF and UHF MRI equipment serves as a fundamental guarantee for scientific research and clinical applications, and is emphasized and supported as a strategic industry in many countries. This paper comprehensively analyzes the global market landscape and core technology competition in HF and UHF MRI equipment, highlights opportunities and challenges for China’s development in this field, and proposes targeted recommendations.