A home-made high pressure apparatus and a static NMR cell capable of standing high pressure up to 10 MPa were employed to study the formation of methane hydrate in SBA-15 with uniform pore size and ordered hexagonal structure. It is found that，under static condition， the introductive period for methane hydrate formation in the mesochannels of SBA-15 is shorter than that for the formation of bulk methane hydrate，suggesting that SBA-15 can promote the formation of methane hydrate. In situ high-pressure ¹H and ¹³C NMR studies show that at certain pressure，even in the presence of excess methane，not all the water molecules confined in the mesochannels of SBA-15 can be completely utilized to form methane hydrate.

The fluidity of erythrocyte membrane in the presence of xenobiotics, such as hydroxylamine derivatives and phenolic compounds was studied by ESR in combination with spin labeling technique. The results indicated that the fluidity inside the membrane decreased evidently in the presence hydroxylamine derivatives and cumyl hydroperoxide, as results of oxidative stress and cross-link of the membrane lipids. In contrast, the mobility of the lipids on the surface of the membrane was increased, mainly due to the direct membrane effect from the small organic molecules. Accordingly, both hydroxylamine derivatives and phenolic compounds enhanced the fluidity of the surface of erythrocyte membrane.

A digital receiver for uses in nuclear magnetic resonance spectrometers was developed. Compared with the traditional ones, the digital receiver described in this study is capable of eliminating completely image peaks resulting from phase errors in the reference signals and unbalance in the gains between the two receiver channels. In addition, the digital receiver has features such as low cost, high flexibility, easy to use and small size. Detailed design strategy and experimental demonstration are given in the paper.

An explosive detection system based on nuclear quadrupole resonance (NQR) is introduced. A special excitation pulse sequence was used to excite and generate NQR signal from the ¹⁴N nuclei in the explosives. However, the amplitude of explosive NQR signal is usually too low (about 10^-8 V) to be observed reliably in natural environment. To overcome this problem, an effective multi-pulse sequence combined with small signal detecting and processing techniques was employed when building the NQR measurement system. Using the system developed, we successfully obtained the NQR signal from a 100 g RDX explosive sample at room temperature with a probetosample distance of 5 cm and an acquisition time of 5 s.

In this paper, the configurations of dibenzene-chromium and its derivatives were optimized by the ab initio method at B3LYP/6-31G(d,p) level. Vibrational analyses were performed, and no imaginary frequency was found in the vibrational spectra of  these  compounds. On these bases, the ¹³C NMR spectra of these compounds were studied  by the GIAO method at B3LYP/6-31++G(d,p) level. It was found that the calculated spectra agreed well with the experimental values.

In this study, atomic electro-negativity interaction vector (AEIV) and atomic state index (ASI) were formulated to describe the chemical environment and atomic state of 255 carbon atoms. Using the multiple linear regression (MLR) technique, a quantitative model was established to define the relationship between the ¹³C NMR chemical shifts and the AEIV/ASI of these atoms. The correlation coefficients (R) and standard deviation (SD) of molecular modeling (MM) were R_MM=0.915 and SD_MM=14.879 ppm, respectively. Leave-one-out (LOO) cross-validation (CV) technique was applied to validate the prediction capability of the model using an external test set, and the R_CV and SD_CV values were found to be 0.909 and 15.324 ppm, respectively. The results indicate that the model established has favorable predictive capability and satisfactory stability in estimation.

Based on chemical shift measurements in N-phenylacetamides, N-phenylbenzamides, N-phenyl-o-hydroxybenzamides and methyl N-phenylcarbamates, an equation: δ_cal=δ_0n+C×(Δ_o+Δ_m+Δ_p) for calculating carbonyl ¹⁷O-NMR chemical shifts of substituted N-phenylamides was formulated. Thirteen substituent parameters were obtained with least-square linear regression. Experimentally measured ¹⁷O chemical shifts of 47 substituted N-phenylamides were used as the test set to examine the accuracy of the calculated results. The confidence limit was found to be 99.5% and the calculating errors for above 95% compounds were less than 3.0 (relative errors 0.3%).

Based on chemical shift measurements in benzoyl fluorides, benzoyl chlorides and benzoyl bromides, an equation: δ_cal=δ_0n+C×(Δ_o+Δ_m+Δ_p)  for calculating carbonyl ¹⁷O-NMR chemical shifts of benzoyl halides was formulated. Thirteen substituent parameters were obtained with leastsquare linear regression. Experimentally measured ¹⁷O chemical shifts of 39 substituted benzoyl halides were used as the test set to examine the accuracy of the calculated results. The confidence limit was found to be 99.5% and the calculating errors for above 90% compounds were less than 5.0 (relative error≤0.5%).

Puerarin, an isoflavone compound, is the bioactive component of traditional Chinese medicine puerarin lobate (wild). A novel diethyl puerarin-7-yl phosphate was synthesized by the Atherton-Todd reaction with high productive yield. It was found that the compound synthesized has two sets of NMR signals at room temperature, suggesting the existence of two conformational isomers in solution. The ¹H chemical shifts of the compound were assigned using two-dimensional NMR techniques, including ¹H-detected heteronuclear multiple-quantum coherence and ¹H-detected multiple-bond heteronuclear multiple-quantum coherence.

A triterpene saponin was extracted from traditional Chinese medicine Cucurbita pepo cv Dayangua. Its structure was determined by 2D NMR. Complete assignment of the ¹H and ¹³C chemical shifts for the compound was obtained. The structure was elucidated to be cucurbitacin E 2-O-b-D-glucoside.

A phenylpropanoid glycoside isolavandulifolioside was isolated from Leonurus heterophyllus. Complete chemical shift assignment for this compound was achieved on the basis of 2D NMR analysis. The structure of the compound was determined.

The “pseudo mirroring image” relationship between  the resonance peaks of the two trans protons of acrylamide (AM) in CDCl₃ and DMSO mixed solvent was studited as a function of the radio of the two solvents. The changes of chemical shifts in different solvents were studied by ¹H NMR and 2D NOESY. Variable temperature ¹H NMR indicated the formation of hydrogen bonds between -NH₂ of AM and the protons of residue water in solvent.

The fruiting bodies of higher Ganoderma are well-known traditional Chinese medicines. The results of many previous studies have indicated that Ganoderma triterpenoids found in Ganoderma sp. are the main bioactive components. In recent years, a great number of novel triterpenoids with unique chemical structures has been isolated from Ganoderma.¹³C NMR is a powerful tool to determine the structure of Ganoderma triterpenoids. In this paper, a meta-analysis was performed on previously reported ¹³C NMR chemical shifts of triterpenoids and another substances isolated from Ganoderma and on their assignment. The characteristics of and interpretation rules for the ¹³C NMR spectra of these compounds were discussed. The results obtained in this study should be useful for future studies investigating the chemical structures, configuration and conformation of Ganoderma triterpenoids.