Metabonomics studies the variations of levels of endogenous metabolites in response to physiological rhythms and external stimuli, providing molecular mechanistic explanations to the effects of pathology, toxins or specific environmental conditions. It has become an important tool in systems biology. With metabonomic approaches, mass spectrometry or nuclear magnetic resonance (NMR) spectroscopy data acquired from biological samples are analyzed with pattern recognition techniques. These approaches have been successfully applied in many research areas, including biomedicine and drug toxicology. In this review, we focused on experimental design, assessment of NMR spectroscopy, pattern recognition techniques and applications of NMR-based metabonomic approaches in studying drug toxicology.

ESR is the most direct and effective technique to detect free radicals, however because most free radicals in biological systems are not stable, it is difficult to detect the free radicals by normal ESR. In order to breakthrough this limit, the spin trapping technique has been developed and successfully applied to detect the free radicals in biological system. More new spin trapping agents and a lot of papers are published in the field every year, which promote the development of free radical biology and medicine. 
We have developed the technique of spin trapping technique to detect super oxide free radical, hydroxyl free radical, lipid free radical generated in lipid peroxidation, NO free radical and single oxygen in biological system. We have also developed a technique to simultaneously measure NO and oxygen free radicals generated from cell and tissues. Using this technique, we investigated the mechanism of free radical generation by cell and tissue, scavenging effects of natural antioxidants on free radicals, the free radical generation mechanisms in inflammation, heart disease, Alzheimer’s disease, Parkinson’s disease, stroke, radiation damage and plant disease. We have got many significant results and published many papers in international journals.

The design and implementation of a high-resolution NMR spectrometer receiver was introduced. PCI-104 was used as the controller of the receiver and served to implement network communication and the other complicate control logic. FPGA was used to control IF receiver board and implement DSP. A special pulse sequence generator that generates acquisition control signal was built in FPGA to reduce coupling between the receiver and other module in the system. The receiver was integrated in a 500 MHz console.

A variable-temperature and sample handling pneumatics system was designed for NMR spectrometer. An ARM with CAN controller is used as the center processor of the system, which controls the airflow and temperature through PID control algorithm. The controller of the design can carry out changing or spinning sample and variable-temperature. This design has many other benefits, including easy control, high precision and low cost.

A high speed and reliable communication system based on the CAN (Controller Area Network) bus, STM32 controller, FPGA (Field Programmable Gate Array) and PCI-104 was designed for nuclear magnetic resonance (NMR) spectrometer. Ethernet-CAN bus communication between the NMR workstation and each controller was established and programmed with reusable method. The results from typical tuning experiment revealed that the CAN-based communication system is an ideal scheme for data communication in NMR spectrometer.

In NMR logging, amplitude of NMR echo train is often weak, and vulnerable to noise contamination originated from either electronic devices or external environment. Both real-time acquisition and noise suppression are critical to echo envelope detection. In this paper, advantages and disadvantages of various echo envelope detection methods were reviewed. The superiority of DPSD (digital phase-sensitivity detection) for NMR echo detection was discussed. The optimal filter window function was obtained from simulation of the echo envelope. Experimental results showed that not only real-time measurement and noise reduction could be achieved by DPSD, but also the amplitude and phase could be extracted accurately.

The main parameters for evaluating the performance of NMR well logging Device include sensitive volume shape, depth of investigation and signal strength. These parameters are determined by the field distribution of the sensor. In order to estimate the performance of NMR well logging device during its prophase design, the field distribution of MRIL-P was simulated by the finite element method, and the field distribution was optimized. Based on the results of simulated optimization, the sensitive volume shape of MRIL-P was obtained, and the relationship between signal strength and working frequency were validated. These results indicated that, in an inhomogeneous field, the signal strength was controlled by field strength, and increased with increasing working frequency. Our results showed that this method can be used to evaluate the performance of NMR well logging device during its prophase design, and direct the overall design.

NMR logging while drilling (LWD) has the advantage of detecting formation in-situ, and is a big progress in NMR logging. Compared with wireline NMR, NMR LWD is often performed in more hostile environment. In this paper, the magnet structures of typical NMR LWD tools, such as MRIL-WD (Halliburton), proVISION (Schlumberger) and MagTrak (Baker Hughes), were simulated and analyzed. Finite element method was employed to calculate the magnetic field distribution. The results were shown to be in good agreement with the typical tools’ nominal features. Based on the results of simulation, we proposed schemes to suppress or eliminate the effects of tool motion during drilling. This work provided insights for NMR LWD tools design, implement and optimization.

The configuration of carbon-17 ethylene bond in pregn-17(20)-ene derivatives has important influence on the pharmacological properties of the compounds. However, the previously used methods for configuration determination of pregn-17(20)-ene derivatives either are time consuming or cannot obtain certain results. In this paper, we proposed to use 1D selective NOESY to determine the configuration of carbon-17 ethylene bond in E- and Z-guggulsterone. The results showed that, by selective inversion of H-20, the NOE spectra of E-guggulsterone showed only the signal from H-21, while that of Z-guggulsterone showed additional signals from H-18 and H-12. Our results indicated that the selective NOE experiment is a rapid and simple method for configuration determination of the carbon-17 ethylene bond in pregnanes.

This paper reviews the commonly-used image reconstruction algorithms in parallel magnetic resonance imaging. First, the reconstruction algorithms used in parallel MRI without acceleration was discussed. Then, the commonly-used reconstruction algorithms in parallel MRI with acceleration, SENSE, PILS, SMASH and GRAPPA, were compared. It was shown that, with the same accelerating factor, the quality of GRAPPA and SENSE reconstructions are the best among the four, while that of PILS reconstruction is the worst. In terms of reconstruction speed, SMASH is the fastest, and GRAPPA is the slowest. The performance of all four reconstruction algorithms degraded with increasing accelerating factor, suggesting that increase of imaging speed is at the expense of the cost of SNR. We also implemented the reconstruction algorithms for parallel imaging on an Matlab GUI platform. The resulting software has the functions of reading raw data, showing sampling trajectory, calculating coil sensitivity, choosing image reconstruction method, analyzing and comparing image quality etc. We believe the software will be helpful for study and research on parallel MRI reconstruction algorithms.

Polarization spectroscopy of saturated absorption was used to lock laser frequency and set up an experimental system of laser-pumped rubidium atomic frequency standard. A preliminary frequency stability measurement was carried out, the results of which showed that a short-term frequency stability of 1.2×10^-11τ^-1/2 was achieved. By analyzing the results, we proposed some approaches to improve the performance of the frequency standard.

By summarizing published literatures, the structural and ¹³C NMR spectral features of steroidal saponins isolated from Tupistra were analyzed. So far, 53 identified steroidal saponins compounds had been isolated from the plant, including 27 spirostanols and their glycosides, 24 furostanols and their glycosides, and 2 furospirostanols. The ¹³C NMR spectra of different steroidal saponins show different features that are related to skeletons and type and position of the substituent groups in the compounds. The findings are helpful for structure elucidation and assignments of the spectroscopic signals of such compounds.

We studied a double transgenic APPSwe/PS1dE9 mouse model using T₂-weighted imaging and histological assessment to detect agerelated amyloidosis and iron load in the hippocampus and cortex. The results indicated that T₂ of older transgenic mice was slightly higher than that of the younger ones, but the difference did not reach statistical significance. We also did not found any significant T₂ difference between transgenic mice and age-matched non-transgenic littermates. Histological assessment revealed an age-related increase of amyloid load in the hippocampus and parietal cortex. Positive iron staining was observed in amyloid-rich regions of 16-month-old APP/PS1 mice, and co-localized, to a large extent, with amyloid deposits. These results indicated that T₂ might not be sensitive enough to detect amyloid and iorn deposition in this model.

The changes of T₂ of water absorbed to wood in an environment of constant temperature of 32 ℃ and relative humidity of 98% was studied and used to reflect characteristics of water distribution and migration. The migration behavior of water molecules were used to explain the interactions between wood and water, and reveal the mechanism of water sorption at the microscopic level. The results of this study suggested that NMR is an effective tool to study the complex relationship between wood and water.

The chemical constituents of the radix of Ilex asprella, separated by column chromatography, were analyzed by MS, ¹H NMR, ¹³C NMR, DEPT, ¹H-¹H COSY, HSQC and HMBC. A triterpenoid, Urs-12-ene-3β, 28-diol, 3-acetate, was isolated from the chloroform extract of the radix of Ilex asprella. The ¹H  and ¹³C NMR chemical shifts of the compound were assigned.

The compound 3,3-dimethyl-3,3′-dibenzyl-2,2′,4,4′-tetraoxaspiro[5, 5] undecane was synthesized. ¹H NMR spectroscopy and theoretical computation was used to characterize the hydrogen atoms in the compound. With Gaussian03 software package, the results of potential energy scanning revealed that four possible conformations existed for the undecane. The ¹H chemical shifts of the four possible isomers were calculated under B3LYP/6-311+g** level. The isomer showed the smallest difference between the theoretical results and experimental results was considered to be the correct conformation. The electron density maps of different isomers were drawn from its CHK files, which revealed electrostatic shielding that was consistent with the change of ¹H chemical shift.

An oligosaccharide, α-D-Gal-(1→3)-α-D-Gal-(1→6)-α-D-Glc-(1→2)-β-D-Fru (BO-1), was isolated from the seed of Bixo orellana. The ₁₃C  and ¹H NMR chemical shifts of the compound were assigned by 1D and 2D NMR techniques, including COSY、HMQC and HMBC.

Clevidipine butyrate is a short-acting dihydropyridine calcium channel blocker. The spectral data of clevidipine butyrate were reported, including UV, IR, NMR (i.e., ¹H NMR, ¹H-¹H COSY, ¹³C NMR, DEPT, HMQC and HMBC) and MS data. The NMR and IR signals were assigned. The molecular structure of clevidipine butyrate was determined.