The glycine-rich RNA-binding protein, AtGrp7, is a component of a negative feedback loop in the circadian clock regulation of Arabidopsis thaliana. In our initial purification trial of the tobacco etch virus (TEV)-cleaved AtGrp7 RNA recognition motif (RRM) domain with the regular protocol, mixed ultraviolet signals of the target proteins and contaminants were observed. A two-step denaturing-refolding protocol was then tested, trying to solve the problem of impurities. The structure of the AtGrp7_1-90 RRM domain was fully recovered by quick-dilution refolding, evidenced by the fingerprint ¹H-¹⁵N HSQC spectrum and CS-Rosetta model structures. Isothermal titration calorimetry (ITC) and NMR titration experiments further confirmed that the RRM domain of AtGrp7_1-90 had proper functions with regards to RNA/DNA binding.

Ubiquitin is a conserved signaling protein. It is able to interact with thousands of target proteins specifically and perform its biological functions via non-covalent interactions. Ubiquilin-1 (Ubql-1) and Rad23A are two transport factors in the protein-degradation process, and both contain ubiquitin-associated domains (UBAs). S65 of the ubiquitin can be phosphorylated specifically by the kinase PINK1, and the phosphorylated ubiquitin has two interchangeable conformations in solution, the relaxed conformation and the retracted conformation. In this work, nuclear magnetic resonance (NMR) methods were used to characterize the regulation of interactions between the ubiquitin and the UBAs of Rad23A/Ubql-1 by phosphorylation. The results indicated that the UBAs selectively interacted with the relaxed conformation of the phosphorylated ubiquitin without affecting the affinity. When interacting with the UBA of Ubql-1, inter-protein binding appeared to be able to promote the transferring from the retracted conformation to the relaxed conformation.

Wide-line solid-state proton nuclear magnetic resonance (¹H NMR) spectrometry is a classical technique to study the phase structures of semi-crystalline polymers. In this paper, the wide-line solid-state ¹H NMR spectrum of semi-crystalline polyethylene was acquired, and fitted with the combination of Gaussian/Sinc, Gaussian and Lorentzian functions. The four signal components decomposed from the wide-line solid-state ¹H NMR spectra were assigned to the crystallization phase, crystalline interface phase, amorphous interface phase and amorphous phase, respectively. The chain dynamics in different phase was also studied with the temperature-dependent wide-line solid-state ¹H NMR method. The difficulties in determining the crystallinity of semi-crystalline polymers with wide-line solid-state ¹H NMR were discussed.

Two-dimensional (2D) NMR logging activation sets are acquisition means aiming at obtaining specific formation information, affecting the adaptability of NMR instruments to different types of reservoirs and the reliability of the original data. In this work, a software with the visualization function for designing 2D NMR logging activation sets was developed using the C# language, based on the component elements and working mechanism of activation. The software supported the design of activation sets for 2D NMR logging and NMR core analyzer. Meanwhile, the software provided three kinds of parameter editing methods, observation mode optimization and graphical display functions, and thus realized flexible adjustment of the activation sets. It solved the problems in the former mainstream 2D NMR logging activation sets, such as low signal-to-noise ratio of the raw data, incomplete loading of fluid relaxation characteristics due to inadequately fixed acquisition parameters and inflexible adjustment etc. In addition, the software also provided outputs for acquisition parameters and acquisition timing.

To some extent, pore throat structures of the rock can be characterized by NMR T₂ distribution and capillary pressure curve. Theoretical analysis showed that NMR T₂ distribution of a rock could potentially be used to derive its capillary pressure curve, providing a quick and non-destructive way to obtain the pore structure distribution data of the reservoir. In this study, the capillary pressure curves of typical cores were constructed from nuclear magnetic resonance (NMR) T₂ distributions using a piecewise power function method. T₂ cutoff values were introduced as piecewise points for the power function. Then the capillary pressure curves constructed with the piecewise power function method and those constructed with the non-piecewise power function method were compared. The results showed that the proposed method had improved precision, with an averaged fitting degree of 0.943 1. Introducing of T₂ cutoff values was proven to be useful in constructing NMR capillary curves by the piecewise power function method.

Ethylene glycol is a raw chemical material for production of polyester fibers used in coating material, dynamite and etc. The presence of trace methyne (CH) containing impurities greatly affects the quality, transportation and storage of ethylene glycol. So far it is difficult to analyze these trace impurities quickly with the traditional methods. Hereby, we demonstrated a simple procedure to analyze the key impurity (1, 2-butanediol) in polymer grade coal-based ethylene glycol by the nuclear magnetic resonance (NMR) multiple signal suppression technique combined with peak shape analysis.

The quantitative relationship between the ¹³C NMR chemical shifts of alkanes and their formation enthalpy was studied. A new approach for calculating the formation enthalpy from the ¹³C NMR chemical shifts was proposed. The experimentally measured formation enthalpy values of 53 alkanes were correlated with the parameters SCS (the sum of chemical shift),P3 (path counts of length three bounds) and n (the number of carbon atoms). The regression results showed a good correlation (R=0.998 2,S=3.5 kJ/mol). The random sampling method and leave-one-out method were used to verify the stability and prediction ability of the model.

Cytochalasins are a group of natural products from fungus, and have been attracting lots of research interests in the field of microbiology. Cytochalasins possess complex and diverse structures, making nuclear magnetic resonance (NMR) based structure elucidation difficult. Chaetoglobosin F is a 10-indol cytochalasin isolated from endophytic Chaetomium globosum growing in the seeds of Panax notoginseng. This paper reported the NMR data chaetoglobosin F, along with the summarization of NMR features of 10-indol cytochalasins, providing a good reference for the further research on cytochalasins.

The ¹H and ¹³C NMR signals of a novel carbazole-isatin based bis-thiocarbohydrozone derivative 2, 1-[(3Z)-2-oxoindoline-3-ylidene]-5-[(9-hexyl-3-carbazolyl)ylidene]thiocarbohydrazone, were assigned, and the structure of the compound was confirmed.

The nucleoside derivative N-isobutyryl-3'-O-(1-fluoro-1,1,3,3-tetraisopropyl-1,3-disiloxane-3-yl)-2'-benzyloxy carbonyl-guanosine (compound 1) was obtained by selectively cleaving the 1,1,3,3-tetraisopropyldisiloxanyl protecting group at 5'-position with pyridinium hydrofluoride. Liquid chromatography-mass spectrometry (LC-MS), gas chromatography-high resolution mass spectrometry (GC-HRMS), liquid one-dimensional/two-dimensional nuclear magnetic resonance (NMR) techniques (i.e., ¹H NMR, ¹³C NMR, ¹⁹F NMR, DEPT, ¹H-¹H COSY, ¹H-¹³C HSQC and ¹H-¹³C HMBC) were used to assign the signals.

Frequency adjusting precision is an important performance indicator of miniaturized rubidium atomic clock (RAC) in some applications, such as the case in GPS disciplined RAC systems. This parameter is determined mainly by the resolution of digital phase-locked loop (PLL) in the frequency multiplier-synthesizer. To improve the frequency adjusting precision of a miniaturized high-performance high-stability RAC developed by our research group, the original RAC circuit scheme was improved by designing and implementing a new decimal frequency multiplier-synthesizer based on a high precision direct digital frequency synthesizer (DDS). Tests showed that this design achieved high precision frequency adjustment, while maintained the frequency stability as high as the original scheme.

Majority of diterpenoid alkaloids are C₁₉-diterpenoid alkaloids found in the plants from the genera Aconitum, Delphinium and Consolida (Ranunculaceae). C₁₉-diterpenoid alkaloids have attached lots of research interests due to their complex structures and remarkable pharmacological activities. This paper reviewed the structural features of natural C₁₉-diterpenoid alkaloids reported in literature from 2010 to 2018, focusing on the NMR spectral characteristics of different subtypes of C₁₉-diterpenoid alkaloids and how their structures could be elucidated from the NMR data. The work may provide a reference for the further research and development of C₁₉-diterpenoid alkaloids.