Layered transition metal disulfides (MS₂) and their derivatives have actual and potential applications in catalysis, ceramics, lubricants, semiconductors, energy storage, electronics and optical devices. In this work, we explored the possibility of characterizing these materials directly using solid-state NMR. Several representative transition metal disulfides (MS₂: M=Zr, Ti, W, Mo and Ta) with known structures were examined. ³³S, ^47/49Ti, ⁹¹Zr and ⁹⁵Mo solidstate NMR spectra were acquired at magnetic fields of 21.1, 14.1 and 9.4 T, respectively. Quantum chemical calculations were performed to assist in understanding the experimental results. The ³³S, ^47/49Ti, ⁹¹Zr and ⁹⁵Mo NMR parameters of  MS₂ were shown to be sensitive to local geometric and electronic environments.

Analyzing metabolic features is an important approach to understand biochemistry of cells. In this work, NMR spectroscopy was employed to analyze the metabolite compositions of HepG2 cells and culture media. More than 50 metabolites were detected and unambiguously assigned based on ¹H  and ¹³C NMR data. These metabolites are known to be involved in metabolic pathways such as tricarboxylic acid cycle (TCA), gluconeogenesis, glycolysis, metabolisms of amino acids, fatty acids, choline, purines and pyrimidines. Metabolomes of the cells and their culture media were shown to offer complementary information on cellular metabolic “fingerprints” and “footprints”. With NMRbased metabonomic approaches, the metabolic effects of quercetin, a plant secondary metabolite, on HepG2 cells were studied. The results of this work demonstrated that NMR is an efficient tool for analyzing cellular metabolome and its responses to drug interventions.

This study evaluated the tumor-targeting efficacy of folate-conjugated magnetic albumin nanospheres with in vitro and in vivo MRI experiments. Human nasopharyngeal epidermal KB cells were used for the in vitro experiment, which were incubated with folate-conjugated and non-folate-conjugated nanospheres for 24 hours. The presence of the nanospheres inside the cells were then detected using MRI and  Prussian blue staining. For the in vivo experiment, nude mice were transplanted subcutaneously with nasopharyngeal epidermal KB tumor. MRI and histopathological examination were used to detect the presence of nanospheres in the tumors after injection. The in vitro and in vivo experiments demonstrated that folate-conjugated nanospheres had significantly higher amount of deposition in the tumor cells/tumors than the non-folate-conjugated nanospheres. It was concluded that folate-conjugated magnetic albumin nanospheres had a better targeting efficacy on human nasopharyngeal epidermal KB cells, relative to the non-folate-conjugated nanospheres.

A mouse model of acute methanol poisoning was established to evaluate the protective effects of rhubarb and vitamin C (Vc) on methanol-induced oxidative stress in different organs. The mice used in the study were randomly divided into five group: blank group, control group, methanol group, rhubarb group and Vc group. EPR spin trapping technique was employed to study the intensity change of spin adducts induced by reactive oxygen species (ROS) free radicals generated in different organs of the mice. Compared with the control group, the animals in the methanol group showed significantly increased amount of ROS free radicals in the organs, suggesting the induction of acute oxidative stress. Rhubarb and Vc were shown to be able to alleviate acute methanolinduced oxidative stress.

Planarian is a free-living worm belonging to the Phylum Platyhelminthes. Because of its special evolutionary status and remarkable regenerative abilities, planarian has emerged as an ideal model organism for the study of experimental zoology, cytogenetics, developmental biology and regenerative biology. Although significant advances have been made in recent studies of planarian, little information is available in metabolome of the worm. In this work, we prepared samples of planarian body extract with the aqueous methanol extraction method, and analyzed the samples with 1D ¹H NMR spectroscopy and 2D NMR spectroscopy (e.g., ¹H-¹H COSY, ¹H-¹H TOCSY, ¹H-¹H J-RES, ¹H-¹³C HSQC and ¹H-¹³C HMBC) on a high-resolution 1 GHz NMR spectrometer. Fifty three metabolites were identified from the planarian body extracts, including amino acids, saccharides, lipids, organic acids, ketone bodies, amines, choline and nucleotide metabolites. The results of this study will provide a basic dataset for planarian metabolome research.

Long acquisition time often hinders the routine application of multidimensional NMR spectroscopy. A common approach to reduce the acquisition time is to replace the commonly used Nyquist grid sampling scheme with a random non-uniform sampling (NUS) scheme. However, NUS is inherently associated with degradation of spectrum quality. It has been demonstrated recently compressed sensing (CS) algorithms can be used to reconstruct highquality spectra from sparse NUS data. In this paper, a CS reconstruction algorithm called “Smoothed l₀ Norm Minimization” was introduced. The typical version of the algorithm was then-modified to improve its robustness under high noise condition. The improved algorithm was applied to reconstruct 1D realvalued signal and 2D NMR spectroscopy, and the results were compared with those obtained by other methods. The results showed that the algorithm proposed had better robustness to noise, and could be used to reconstruct high-quality spectra with fewer sampling data.


Truncated singular value decomposition (TSVD)-based methods are often used for two-dimensional inversion, but can suffer from drawbacks such as failure to locate an appropriate truncating position, sensitivity to noise, and generation of artificial signals. In this paper, we proposed an improved TSVDbased inversion method for 2D NMR. First, an accurate locating method using a progressive refinement regional searching algorithm was employed to find the largest preserving number of singular values. Then we calculated the minimum preserving number according to the clustering level of singular values. Lastly, an iterative TSVD method was implemented. The results on simulated and actual data set were reported. Compared with the existing TSVD-based methods, the proposed iterative TSVD method was shown to be more robust, and capable of producing spectra with higher resolution.

The radio frequency (RF) coil is a key component in the nuclear quadrupole resonance (NQR) explosive detection system to pick up the signals. In this study, we aimed to optimize the design of small-sized solenoid coils for NQR explosive detection, including the diameter, length and number of turns of the coil. Experimental tests showed that the optimized coil had high sensitivity, and could be  used to detect the NQR signals of explosives quickly and accurately.

A microwave frequency multiplier is introduced in this paper, which may be used to further miniaturize rubidium atomic clocks. A digital phase-locked loop (PLL) technique was used in the microwave frequency multiplier to transform the 10 MHz signal from VCXO to a 6 834.68XX  MHz signal. After binary frequency shift keying (2FSK) modulation and power optimization, the microwave signal was fed into the microwave cavity of the physics package. This multiplication scheme makes the circuit board smaller and the debugging process easier. The circuit with this multiplier was implemented and used in miniaturized rubidium clocks. Preliminary test showed that the short term frequency stability achievable was 1.8×10-¹¹τ^-1/2.

Fluacrypyrim is a new miticide, and a novel STAT3 activation inhibitor. In this study, the infrared spectrum, ultraviolet spectrum, 1D/2D NMR spectra and mass spectra of fluacrypyrim were obtained and interpreted. All the NMR signals were assigned. The position/intensity of the absorption band in the ultraviolet spectrum was used to analyze the chromophores. The infrared spectrum was used to elucidate the effects of the fluorine atoms on the structure of the compound.  According to the mass spectral data and the main fragment ions, the possible fragmentation pathways were obtained. The structure of the compound was determined.

NMR spectroscopy was used to investigate the stoichiometry, three-dimensional geometry and formation constant of capsaicin and β-cyclodextrin complex. Capsaicin/β-cyclodextrin solutions with different concentration ratio were measured. Inflection point on Job's curve measured by ¹H NMR appeared at r=0.5. Two-dimensional ROESY and DOSY spectra of the complexes were obtained. Cross peaks in the ROESY spectra appeared between capsaicin H-1 to H-8 and β-cyclodextrin H-3′, H-5′, H-6′. Apparent diffusion coefficients of protons in cyclodextrin and capsaicin were measured with DOSY. The results showed that the stoichiometry of the capsaicin complex was 1∶1 and the isopropyl side of capsaicin entered into the hydrophobic cavity of β-cyclodextrin from the wider rim while H-1 to H-8 of capsaicin were included into the hydrophobic cavity completely. The diffusion coefficient of complex was 2.95×10^-10m²/s.

Orlistat is a potent and specific inhibitor of gastric and pancreatic lipases. The structure of orlistat was identified by a series of spectroscopic techniques including NMR, UV and IR. The ¹H  and ¹³C NMR signals of orlistat were assigned by DEPT, COSY, HMBC and HSQC.

The 1, 4-disubstituted 1, 2, 3-triazoles were synthesized by a click chemistry reaction, copper (I)-catalyzed 1, 3-dipolar cycloaddition of alkynes with azides, under mild conditions with very high yields and dramatic rate acceleration. In order to obtained quinolinone compounds with terminal ethynyl, 1-(prop-2-yn1-yl)-7, 8-dihydroquinoline-2, 5(1H, 6H)-dione (3) was prepared from 7, 8-dihydroquinoline-2, 5(1H, 6H)-dione (1) by alkylation reaction. Two configuration stereoisomers of 3 were isolated by recrystallization and silica gel column separation. Complete assignment of the ¹H  and ¹³C NMR chemical shifts of the compound was obtained by 2D NMR techniques, including ¹H-¹H COSY and HMQC. The two configuration stereoisomers of 3 were determined by NOESY.

Two-dimensional NMR spectroscopy is frequently used in natural products research for structure elucidation and studies on structure-activity relationship. In this article, the commonly used two-dimensional NMR spectroscopy techniques for natural products research are reviewed. The merits of each technique are discussed. In particular, the new two-dimensional NMR spectroscopy methods/experiments emerging in recent years (i.e., H2BC, new H2BC, HAT HMBC and HSQC-ADEQUATE) and their applications in natural products research are introduced in detail.