Paramagnetic relaxation enhancement (PRE) refers to acceleration of relaxation rates via dipole-dipole interactions between an unpaired electron and a nucleus. The theoretical framework of PRE was laid in the 1950s, yet its applications in studying protein structures only took place in the last decade. In this review, the theories underpinning PRE and the approaches to measure PRE rates are introduced. The commonly used paramagnetic probes for generating PRE in protein systems are reviewed. The principles of using PRE to characterize protein ground-state structure and transient excited-state structure are described. Further improvements of PRE techniques affording more detailed and comprehensive information regarding protein structure and dynamics are envisioned.

Pulse programmer is an integrating part of NMR spectrometer, which is used to generate RF pulse and to receive echo trains signals. Taking advantage of the synchronous performance and excellent timing control capacity of FPGA, a FPGA-based pulse programmer for low field NMR spectrometer was designed to generate pulse sequences for different NMR experiments. Flexible control of the frequency, phase and amplitude of the RF pulses could be achieved with this pulse programmer. Performance of the pulse programmer was evaluated with measurements of transverse and longitudinal relaxation rates of CuSO₄ solution under uniform magnetic field (0.540 Tesla). The pulse programmer was also used to collect echo trains signals with high signal-to-noise ratio.

The design and implementation of a broadband RF power amplifier used in nuclear magnetic resonance spectrometer were introduced. Based on a two-stage architecture, the power amplifier was composed of a high frequency module, a broadband module and two directional couplers, to meet various requirements of NMR experiments. The rise time, fall time and power linearity of the power amplifier was measured on a home-built 500 MHz NMR spectrometer. Comparison of NMR sensitivity demonstrated good performance of this power amplifier in common NMR experiments.

The composition of coal tar from the Xiaohuangshan region, Xinjiang was studied by NMR spectroscopy and IR spectrometry. Structure parameters of the tar were calculated, and used to evaluate the degree of coalification and hydrocarbon generation capacity of the crude coal. The average aromatization-carbon ratio was found to be 0.78, carbon number (N) 1.64, replace index (σ) 0.49, and condensation index (Q)0.51. It was found that there were many alkyl-side chains connecting to the condensation aromatic nuclei, whose chain length was relatively short. Structural information was yielded from normalized and integrated IR spectra with the OPUS software. The parameters obtained from the NMR and IR spectra indicated that the crude coal was in medium metamorphic grade, and belonged to humic coal containing mainly vitrinite. According to the hydrocarbon generation mechanism, the gas potentiality of the coal tar was found to be better than oil, with its gas potential carbon mainly located in the methyl units. It was concluded that the coal from the Xiaohuangshan region can be used as the raw material to producing coal gas.

¹H NMR and self-diffusion NMR techniques were used to investigate the phase transition and diffusion property of two PNIPAs with different molecular weight distribution (MWD) in D₂O. It was found that MWD had significant influence on the phase transition and diffusion behaviors of PNIPAs. The broad-MWD PNIPA showed a smoothly decreased lower critical solution temperature (LCST)concentration curve, whereas the curve of the narrowMWD PNIPA decreased rapidly first, and then became flat. In the selfdiffusion experiments, the decay curve of the broad-MWD PNIPA showed a certain curvature, which became bigger and bigger with decreasing temperature and increasing concentration. But the decay curve of the narrow-MWD PNIPA was a nearly straight line, and the influences of temperature and concentration were minimal. Comparing the mean self-diffusion coefficient analyzed by a stretched exponential relation based on the classical Kohlrausch-Williams-Watts equation with that fitted with Equation (1), it could be shown that the former method is less susceptible to the influence of MWD.

NMR quantitative analysis of drug is the method with simple operation and use just a few amount of samples. The method can accomplish the qualitative as well as the quantitative analysis simultaneously，and do not need any standard compound but only the common internal standard for the quantitative analysis. The analysis speed and the precision of the method is close to the HPLC method. In this paper，the results of determination for water-soluble vitamin by NMR quantitative analysis with chemical analysis have been compared .The experiment  shows the  results of the NMR quantitative analysis are coincident with the result of the chemical method.  Therefore，the NMR quantitative analysis method can be used market regulation of drugs.

The ¹H NMR NOESYPR1D technique was used to analyze quality stability of complex prescription Chinese drugs. Shuanghuanglian oral liquid produced by different companies was analyzed by the method, and indices for similarity were established. The results showed that the method described in the paper can be used to assess the quality of Shuanghuanglian oral liquid effectively.

A theoretical method was proposed to study the optical and EPR spectra of PbMoO₄: Yb³⁺ crystal. The related formulas of optical and EPR spectra were derived from the crystal-field theory. A 14-order energy matrix of 4f¹³ electronic configuration in D_2d point symmetry was constructed by these formulas. The optical and EPR spectra of PbMoO₄: Yb³⁺ crystal were investigated by diagonalizing the energy matrix. The theoretical results were found to be in good agreement with the experimental values. In addition, the crystal-field parameters were determined by calculation.

Wall shift is the main problem for improving long term stability of atomic hydrogen clocks. In this paper, a simple method for measuring wall shift was introduced, and the possible techniques for eliminating the wall shift and improving the long term stability of hydrogen atomic clocks were discussed.

Gallium (III) triflate-catalyzed reaction between o-phenylenediamine and ethyl propiolate under solvent-free and ultrasonic irradiation conditions produced a novel 1, 5-benzodiazepine derivative with a yield rate of 88%. Complete assignment of the ¹H  and ¹³C NMR chemical shift of the compound was obtained using 2D NMR techniques, including DEPT, ¹H-¹H COSY, ¹H-¹³C HMQC and ¹H-¹³C HMBC. Mass fragmentation pathway was proposed based on the high resolution MS spectrum of the compound.

A new series of (E)-3-(4-hydroxyphenyl)-1-(piperidin-1-yl)prop-2-en-1-one derivatives were designed and synthesized. ¹H and ¹³C NMR spectral assignments of these compounds were presented by one- and two- dimensional NMR experiments and conformations were analyzed by ROESY, variable-temperature NMR spectroscopy and molecular modeling.

The structure of curcumol was modified via a two-step reaction: exocyclic double bond oxidation and oxygen bridges acylation within the seven-membered ring. The reaction product was purified by silica gel column chromatography. Compound 2 was characterized by IR, ESI-MS, ¹H NMR, ¹³C NMR and 2D NMR (i.e., gCOSY, gHSQC and gHMBC) techniques. The ¹H  and ¹³C NMR signals of compound 2 were assigned. Its structure was elucidated as 8-hydroxyl -12-isopropyl-2-methyl-tricyclo[6.2.2.0^1,5] dodecane-10-oxa-6, 9-dione.

The chemical constituents of Iris tectorum Maxim. were extracted with 95% alcohol, isolated by column chromatography on silica gel, and purified by recrystallization. The structures of the compounds were analyzed on the basis of the spectral data. A phenolic diglycoside, Tectoruside, was isolated from the n-Butanol portion of the extract, and its structure was elucidated by various spectroscopic data, including 2D NMR. The ¹H and ¹³C NMR chemical shifts of the compounds were assigned. Its structure was found to be 1-{3′-methoxy-4′-[O-β-D-glucopyranosyl (1→6)-β-D-glucopyranosyl\]phenyl}ethanone.

The ¹³C  and ¹H NMR chemical shifts of gefitinib were assigned using 1D and 2D NMR techniques, including ¹H-¹H COSY, gHMQC and gHMBC. The effects of ¹⁹F substitution on ¹H and ¹³C NMR spectra of the compound were investigated.

Localized magnetic resonance spectroscopy (MRS) is a non-invasive technique for acquiring in vivo biochemical and diagnostic information, acting as a powerful complement to MRI. It can provide important information for clinical diagnosis and disease prediction. However, 1D in vivo ¹H MRS has the problems of peak crowding, low spectral resolution and difficult peak identification. The twodimensional (2D) MRS has been introduced to address these problems to a large extent. In this review, we analyzed the advantages and disadvantages of several typical 2D MRS methods. Their in vivo  applications in brain, muscle, breast and prostates were also discussed. Although 2D MRS has the limitation of long experimental time, it still holds some unique advantages and presents a promising prospect according to the latest research.