An apparatus for ESR and ESR imaging at L-band (1.05 GHz) was built in our laboratory, consisting of L-band ESR spectrometer, three sets of gradient coils and a personal computer-based data acquisition system. The sample cavity is a 3-loop 2-gap reentrant resonator, accepting samples with sizes up to 20 mm in diameter and 30 mm in length. The resonance frequency of unloaded resonator is 1.05 GHz. The microwave oscillator frequency is locked to the resonant frequency of loaded resonator by means of automatic frequency control (AFC). Linear magnetic field gradients (up to 2 mT/cm in amplitudes) in the X-, Y-, and Z-directions are produced by gradient coils, and have a linear range of 40 mm measuring from the center of the magnet. All projections in imaging were acquired as single scans with constant sweep time. To accurately compute the spatial distribution of the spins, the line shape function that causes line-broadening of the ESR signals needs to be removed from the observed projections. Three- dimensional ESR image is constructed based on the Lauterbur's method. Using this system, we studied the spatial distribution of TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) nitroxide radicals in sample tube. Stack images of ESR-CT and 2D, 3D ESR images were obtained.

2D NMR techniques (COSY, TOCSY, HMQC, HMQCTOCSY, HMBC, NOESY) were used to elucidate the structure of schnabepeptide, a cyclic octopeptide isolated from the whole plant of schnabelia oligophylla Hand. Mazz. (Lamiaceae). The proton-coupling network shown in the TOCSY spectrum suggests that the octopeptide contains eight amino acid residues (a L-Ser, a L-Ile, a Gly, a D-Trp, two L-Val and two Pro). The 2D NOESY and HMBC spectra show the sequential connectivity of schnabepeptide is cyclo-(NH-Trp-Val-Gly-Val-Ser-Ile-Pro-Pro-CO).

Using nuclear magnetic resonance spin-lattice relaxation time (T₁), spin-spin relaxation time (T₂), self-diffusion coefficient (D) and 2D NOESY techni
ques, the micellization process of sodium dodecyl sulfate (SDS) in polyacrylamide (PAM) aqueous solutions was studied. The molecular dynamic behaviors of SDS in the presence of PAM were compared with those in a PAM-free aqueous solution. These results suggest that: (1) the critical micelle concentration of SDS is lowered in the presence of PAM; (2) both the translational mobility and the chain plasticity of PAM decrease with the increase in SDS concentration; (3) the direct congregation between PAM and SDS can not be observed using the contour plot of 2D NOESY.

Under alkali treatment, Hemslecin A becomes its isomer Hemslecin C by acetyl migration. In this paper, the chemical structure of Hemslecin C was eluci
dated unambiguously by NMR spectroscopy, including 2D ¹H-¹H COSY, HMQC and HMBC. The ¹³C and ¹H chemical shifts of the compound were ass
igned.

A new dimeric iridoid glucoside, chrysathain, was isolated from the Chinese medicinal plant Lonicera chrysatha. Its structure and configuration were e
lucidated by 1D and 2D NMR spectroscopy. The ¹H and ¹³C NMR chemical shifts of the compounds were assigned.

1D and 2D NMR techniques were used to elucidate the structures of 2,2,6,6-Tetramethyl-4-piperidinol and 1,2,2,6,6-pentamethyl-4-piperidinol. The reson
ance of all the carbon atoms and protons in the compounds were assigned, and the stereo structures of the compounds were determined by the NOESY technique.

Pulse sequence generator is an essential component in a nuclear magnetic resonance (NMR) spectrometer. In this paper, a PC based pulse sequence generator is proposed, which is simpler and more economic compared to the conventional pulse sequence generators. It accuracy and stability in timing control are discussed for PC running on Windows 98 and Windows XP operating systems. The experimental results confirm that the PC based pulse sequence generator is useful in conventional NMR spectrometers where the static magnetic field strength is equal to or lower than 2.4 T.

5β-CHOLESTAN-3β-OL was determined as the major steroids in marine sponge -Hymeniacidon perleve- with a level of ca. 1 000 ppm. Cholesterol was fou
nd in the 5β-CHOLESTAN-3β-OL crystal using ¹H NMR spectroscopy, while GC-MS failed to obtain the same results. Using ¹H NMR spectroscopy, standard mixtures of  5β-CHOLESTAN-3β-OL and cholesterol were studied to accurately quantify the steroids that are difficult to be separated by chromatography.

The Atheron-Todd reaction has been used extensively for the synthesis of phosphates and phosphoroamidates. In this study, phenol and eyhyl-salicylate were phosphorylated by a modified Atheron-Todd procedure through dropping DEPH and tetrachloromethane into a solution mixture of phenol, triethylamine and dioxane and a solution mixture of ethyl-salicylate, triethylamine and dioxane respectively. Two diethyl substituted phenyl phosphates were obtained with good yields, their structures were elucidated by NMR and ESI-MS/MS.

A filamentous fangus Ascomyceters Hypocreaceae Hypomyces (Fr.) Ful SP. was obtained from the western mountainous area of Yunnan province of China, and cultured in the laboratory. A chemical component of the metabolite of the fungus had been identified as Elsinochrome A (EA) by UV spectrum, elemental analysis, MS, ¹H NMR, ¹³C NMR and X-ray analysis. Under appropriate conditions, the chloroform solution of EA was mixed with the chloroform solution of dibenzylamine (DBA). Irradiation of the mixed compound with a visible-light exhibits stronger absorption as observed by  a Varian E-115 ESR measurement. The results suggest that EA cause  DBA to  convert to oxynitride radical.

Magnetic resonance molecular imaging, which uses magnetic resonance imaging as a noninvasive tool to study in vivo cellular molecular events involved
in normal and pathologic processes, has recently become a hot topic in the research field of magnetic resonance imaging (MRI). Still in its early stage, the research on magnetic resonance molecular imaging has been growing rapidly due to the great values and potentials of the techniques in both clinical medicine and basic biomedical investigations. In this paper, the recent developments of magnetic resonance molecular imaging are reviewed. The methodological aspects of several types of  commonly used magnetic resonance molecular imaging techniques and the molecular probes used in the techniques are briefly introduced.

With the rapid development of polymer science and catalysis technology, it has become more and more important to understand the microstructures of polymer and catalyst. In the paper, the recent applications of ESR and NMR in studying metallocene catalyst and polyolefin are reviewed. The results suggest that the ESR and NMR techniques useful research tools in studying the microstructure of polymers and catalysts.

General conditions that affect High Resolution Magic Angle Spinning NMR (HR/MAS) were studied in this paper including five resins, five solvents and t
emperature. A Solid phase synthesis of o-glycosylated Fmoc protected amino acid was then monitored. The results demonstrated that both resin and the solvent are critical factors in affection of acquisition of NMR singlets.