B1 domain of staphylococcal protein G (GB1) is a widely used model protein for developing in vivo and in vitro protein structural determination methods based on paramagnetic nuclear magnetic resonance (NMR) such as pseudocontact chemical shift (PCS) and paramagnetic relaxation enhancement (PRE). However, few previous studies have investigated the interactions between GB1 and metal ions, especially paramagnetic ions. In this study, the interactions between GB1 and divalent/lanthanide metal ions were studied by NMR spectroscopy. It was found that GB1 weakly bound with paramagnetic lanthanide ions and paramagnetic divalent ions, including Cu²⁺, Mn²⁺ and Co²⁺. In contrast, GB1 did not bind with diamagnetic divalent ions, such as Ca²⁺, Mg²⁺ and Zn²⁺. Furthermore, it was demonstrated that there were two binding sites for Cu²⁺ in GB1, but only one for lanthanide ions and divalent ions Mn²⁺ and Co²⁺. The current study demonstrated that NMR spectroscopy is a powerful tool to study weak binding between protein and metal ions. And the results indicated that care must be taken to avoid possible interference to paramagnetic NMR data when using GB1 as the model protein.

The combination of doxorubicin and paclitaxel is widely used in clinical cancer therapy. Due to enhanced permeation and retention effects of nanomaterials in tumor tissues, nanocarriers with good biocompatibility have been designed to encapsulate doxorubicin/paclitaxel, and used to facilitate delivery of the drugs to achieve better therapeutic outcome. In this study, NMR-based metabonomic analyses were used to study the metabolic profiles in spleen tissues of normal healthy mice and of 4T1 tumor-bearing mice, which were treated with either saline, or doxorubicin/paclitaxel in their free forms, or doxorubicin/paclitaxel encapsulated in nanocarriers. The results demonstrated that treatment with the free forms of doxorubicin/paclitaxel remitted tumor-induced disturbances in gut microbiota, while treatment with nanocarrier-encapsulated doxorubicin/paclitaxel alleviated increased glucose and fumarate metabolism associated with tumor bearing. In contrast, tumor-related splenomegaly and metabolic alterations in amino acids, organic acids, nucleic acids and choline, both attributable to immune responses of the spleen, were not ameliorated by drug treatment. This could also be due to the fact that the treatment period was too short to have any significant effects. This work provided metabolic phenotypical information of the spleen tissues in 4T1 tumor-bearing mice, and helped to understand the metabolic impacts of drug delivery systems on the spleen.

To provide guidance to clinical diagnosis and develop individual-based treatment/prognostic evaluation, this study explored the correlations between morphological characteristics of glioblastoma (GBM) measured by conventional MRI and expression levels of GBM-specific molecular biomarkers. MRI data of 60 patients with histopathologically confirmed GBM were analyzed retrospectively, from which the morphological characteristics of GMB (i.e., TLD, ELD and CTE/TLD ratio) were measured. Histochemical staining was used to measure the levels of GBM-specific molecular biomarkers (i.e., EGFR, IDH-1, TP53, PTEN and NEFL), which were calculated as the product of staining index and stained area. Correlations among the morphological characteristics and the levels of molecular biomarkers were assessed using multivariate logistic regression analyses. There was a significant correlation between TLD and EGFR level (r=0.796). The correlation between TLD and PTEN level was positive (r=0.533), while the correlation between TLD and IDH-1 level was negative (r=-0.672). CTE/TLD had a positive correlation with EGFR (r=0.622) and PTEN (r=0.638) levels, along with a negative correlation with IDH-1 level (r=-0.493). ELD had no significant correlation with the levels of all five molecular biomarkers. It was concluded that the morphological characteristics of GBM derived from conventional MRI had correlations with the expression levels of EGFR, IDH-1 and PTEN, and it was possible to derive heterogeneity, molecular classification and prognosis of GBM using conventional MRI.

Both compressed sensing (CS) and parallel imaging (PI) can be used to accelerate magnetic resonance imaging (MRI) by under-sampling the k space data. Several methods combining CS and PI have been proposed to further improve the scanning speed. In this paper, we proposed a new approach to combine CS and PI. We used GRAPPA (Generalized Autocalibrating Partially Parallel Acquisitions) algorithm to reconstruct local under-sampled k space data, and CS to reconstruct the whole k space data for each coil. In the CS reconstruction step, we constrained that the reconstructed k space data should be assimilated to both the sampled k space data and the reconstructed k space data by GRAPPA. In addition, we designed a new sampling strategy to improve the quality of image reconstruction. In vivo imaging results demonstrated that the proposed approach could effectively remove artifacts and improve the image quality.

Reconstruction, post-processing and visualization of images are important parts of magnetic resonance imaging (MRI). In this work, a new open source framework, namely Yet Another Pipeline (YAP), was proposed for reconstruction, post-processing and visualization of MR images. With YAP, researchers can build customized image-processing pipelines with ease. Compared with the existing open source frameworks, YAP has the following features:(1) it has an interface-based design, enabling function extension by plugin development; (2) it uses a script language with straightforward grammar, making it easy to build and modify customized pipelines; (3) it supports branches in the pipelines, facilitating pipeline building and debugging. YAP has been implemented on a commercial MRI system.

Magnetic resonance imaging (MRI) is a widely used medical imaging technique. In MRI system, gradient magnetic fields are used to code spatial information. However, the fast-switching electric currents in the gradients coils used to generate gradient fields also induce vortex electric field, often referred as eddy current, in the surrounding metal conductors. In this paper, a method for eddy current field measurement was proposed. Based on the Faraday law of electromagnetic induction, an eddy current field measuring device was designed. Combining hardware acquisition and software processing, the eddy current field was obtained by subtracting the ideal gradient field from the magnetic field measured experimentally, whose waveform could be displayed in real time. The proposed method was verified by experimental results.

CPMG sequence is widely used to measure crosslink density of rubber. However, the crosslink density obtained by this technique has a strong dependence on the interval times between the pulses in CPMG sequence, and the results measured have only a weak correlation with rubber hardness. To overcome this shortcoming, we proposed in this work to construct a ¹H T₂ relaxation curve by summing Gaussian-weighted CPMG relaxation curves acquired at by varying the interval time between the pulses in CPMG sequence. Using the multi-echo Gaussian-weighted relaxation curve to calculate the crosslink density gave results that had greatly improved correlation with the rubber hardness. The new method was also fast and efficient, as it took only one-tenth of the experimental time required for the conventional ¹H double quantum NMR (¹H DQ NMR) experiment.

NMR spectra of aqueous solutions of cetyltrimethylammonium bromide (CTAB)/triton X-100 (TX-100), sodium dodecyl sulfate (SDS)/TX-100 and CTAB/TX-100/SDS surfactant mixtures were acquired. The proton chemical shifts of each component and their dependence on concentration were determined and used to derive the critical micelle concentrations (CMCs) of CTAB, TX-100 and SDS in each mixture. It was found that, in several cases, the role played by the steric effect in the synergism of surfactant mixtures were not less than that of the electrostatic interaction. The larger the cross sectional area of the polar head was, the greater the synergy would be. It is concluded that the steric effect is a major player in the synergistic effect of surfactant mixtures, especially when the electrostatic interaction is weak.

NMR techniques were used to study the relative arrangement and interaction sites in mixed micelles formed in NP-10/Tween40 and NP-10/C₁₀E₆ aqueous solutions. The results of two-dimensional NOESY experiments and relaxation time measurements showed that the interaction site of these two pairs of mixed surfactants were similar, but the intermolecular interaction between NP-10 and Tween40 was stronger than that between NP-10 and C₁₀E₆. T₂ measurements demonstrated that inter-heteromolecular interactions decreased when the molar concentrations of Tween40 and C₁₀E₆ were larger than 2 and 4 folds of that of NP-10, respectively. Under such circumstances, the inter-homomolecular interactions began to play a key role, indicative of the ideal mixture molar ratio and the change of synergistic effect in the complex systems. T₂/T₁ ratio measurements indicated that molecular chain movement in the NP-10/Tween40 mixture was more limited than that in the NP-10/C₁₀E₆ mixture. The above conclusions were verified by spatial distance measurements.

Two C₁₉-diterpenoid alkaloids, homochasmanine (compound 1) and 14-debenzoylfranchetine (compound 2), were isolated from the roots of Aconitum handelianum. Their structures were elucidated by one-dimensional and two-dimensional nuclear magnetic resonance (NMR) techniques, including ¹H NMR, ¹³C NMR, DEPT, ¹H-¹H COSY, HSQC, HMBC and NOESY. The ¹H and ¹³C NMR signals of the compounds were completely assigned.

An ibuprofen-phillygenin ester was synthesized through the Schotten-Baumann reaction with ibuprofen and phillygenin as the starting materials. Ultraviolet absorption (UV) spectrum, infrared absorption (IR) spectrum, matrix-assisted laser desorption/ionization-mass spectra (MALDI-TOF-MS), and one-dimensional/two dimensional nuclear magnetic resonance (NMR) spectra (i.e., ¹H-NMR, ¹³C-NMR, ¹³C-DEPT, ¹H-¹H COSY, ¹H-¹H NOESY, ¹H-¹³C HSQC and ¹H-¹³C HMBC) of the compound were collected. All ¹H and ¹³C NMR signals were assigned.

Ultraviolet (UV) spectrum, infrared (IR) spectrum, high resolution-mass spectrum (HR-MS), nuclear magnetic resonance (NMR) spectra (i.e., ¹H NMR, ¹³C NMR, DEPT, ¹H-¹H COSY, ¹H-¹³C HSQC and ¹H-¹³C HMBC) of ecabet sodium were collected and analyzed to elucidate its structure. All ¹H and ¹³C NMR signals were assigned.

4-Amino-5-chloro-2,3-dihydro-N-[1-(3-methoxypropyl)-4-piperidinyl]-7-benzofurancarboxamide was synthesized by amide condensation reaction using 4-amino-5-chloro-2,3-dihydrobenzofuran-7-carboxylic acid and 1-(3-methoxypropyl)-4-piperidinamine as the reactants. The resultant compound, also named prucalopride, is a derivative of dihydrobenzofuran 5-H4 receptor antagonist, and an important drug for treating chronic constipation. The NMR spectrum of prucalopride is crowded and complex due to the fact that there are many carbon atoms in the molecule have similar chemical environment. In this study, ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) and liquid chromatographyhigh resolution mass spectrometry (LC-HRMS) were used to analyze the composition of prucalopride. ¹H NMR, ¹³C NMR, DEPT, ¹H-¹H COSY, ¹H-¹³C HSQC and ¹H-¹³C HMBC spectra of the compound were collected, and its ¹H and ¹³C NMR signals were assigned.

The frequency stability of a passive rubidium atomic frequency standard (RAFS) largely depends on the performance of the microwave cavity used in the physics package. In this paper, a large-size slotted tube microwave cavity with an inner diameter of 40 mm, as well as the physics package based on this cavity, were designed and built. Theoretical calculations and experimental results showed that the magnetic lines inside this cavity were highly parallel to the quantization axis. The frequency discrimination slope and the shot noise of the physics package were measured. The results showed that the cavity could be used to realize an RAFS with frequency stability of 2×10^-13τ^-1/2.