Escherichia coli (E. coli) is often used to produce recombinant proteins rapidly with high yield. However, the bacteria expresses non-target proteins unexpectedly in many cases, some of which may later be proven useful. Full characterization of these unpredicted proteins are usually expensive and time-consuming. In this study, we used E. coli to express neuron- restrictive silencer factor/RE1-silencing transcription factor (NRSF/REST) functional motif ZnF2-8, which is involved in the interaction of NRSF/REST with neuron-restrictive silencer element (NRSE/RE1) dsDNA or small non-coding dsRNA for neuron gene transcriptional repression or activation. Overexpression of a non-target protein was observed. Two-dimensional ¹H-¹⁵N HSQC NMR spectroscopy, X-ray crystallography and other biochemical assays were used in combination to characterize the non-target protein to be b-lactamase.

Solid-state NMR spectroscopy was used to study the segmental motion of high-crystallinity PEO8∶NaPF6 electrolytes with different PEO molecular weights (Mw =1 000 and 6 000 g/mol, respectively). ¹³C-magic angle spinning (MAS) NMR spectra and static powder patterns, as well as static 2D exchange spectra, revealed that large-angle reorientation of the crystalline PEO segments in both PEO8∶NaPF6 complexes starts at a very low temperature (~243 K), similar to the case in pure crystalline PEO. At higher temperature, long-range reorientation gives rise to a well-defined high-temperature powder pattern of uniaxial chemical shift anisotropy (δ₃₃ > δ₂₂ = δ₁₁), perhaps as the result of flipping of PEO. In contrast to other PEO/Na (Li) solid electrolytes, the segments in crystalline PEO8∶NaPF6 are highly mobile even when coordinated with Na+, and this is comparable with PEO. It is suggested that the segmental motion in crystalline PEO8∶NaPF6 electrolyte can enhance ion transportation along the coil, improving ionic conductivity.

Solid-state NMR techniques were used to study the structure and confined dynamics of poly-methyl methacrylate (PMMA)/laponite nanocomposite. ¹H magic angle spinning (MAS) spectra and relaxation experiments indicate that organic modifiers (AIBA) interact strongly with laponite nano-sheets, and the structure of PMMA nanocomposite is homogenous at the scale of several nanometers. The results of ¹³C spin-lattice relaxation times (T₁,C) experiments indicate that mobility of the PMMA segments, especially the carbonyl groups, in nanocomposite decreases under the confinement of laponite nano-sheets. ¹³C SUPER experiments further indicate that the incorporation of laponite induce a slight change of the CSA line shape of PMMA carbonyl groups.

α-synuclein is an intrinsically disordered protein, and is implicated in Parkinson's disease. Previous studies have found that the aggregation rate, fibril structure, propagation and cytotoxicity of α-synuclein change markedly with salt concentration. However, the underlying molecular mechanisms remain poorly understood. In this work, 3-fluorotyrosine (3FY) labeling was introduced into α-synuclein, and the conformational changes of the protein under different salt concentrations were studied by ¹⁹F NMR. It was found that the protein was more compact at low salt concentration than at high salt
concentration; and such conformational changes may account for the fibril morphology diversity and physiological effects of the protein at different salt concentrations. It was also concluded that ¹⁹F NMR is a sensitive technique to measure conformational change of intrinsically disordered protein.

It is well-known that, in magnetic resonance imaging (MRI), the presence of spike noise in the K-space will degrade the quality of reconstructed images. In this work, we proposed a method to remove spike noises based on the non-linear conjugate gradient (NLCG) reconstruction algorithm of compressed sensing (CS). The traditional CG algorithm reconstructs images in the wave-domain, making it difficult to remove spike noises. The proposed algorithm is a partial K-space reconstruction algorithm. Using image sparsity as a restrain, the algorithm reconstructs only the data which is covered by spike noises. Compared with the interpolation and NLCG algorithm, the proposed algorithm was shown to yield better images with less artifacts without the need to know the accurate localization of the spike noises.

Polarization transfer ¹³C NMR techniques, such as DEPT and its modified versions (i.e., DEPT⁺⁺, Q-DEPT and Q-DEPT⁺), are frequently used in the analysis of complex mixture, given its high sensitivity and resolution. However, the practical use of quantitative DEPT experiments are often hampered by spectral distortions, which makes accurate quantification difficult. In this study, we incorporated elements of the Q-DEPT sequence into the DEPT⁺⁺ pulse sequence, with the aim to eliminate spectral distortions in Q-DEPT⁺. The polarization transfer mechanisms underlying DEPT⁺⁺ were analyzed. It was
found that it is possible to obtain distortionless spectrum in quantitative DEPT++ experiment simply by calibrating the flip angle of the read pulse.

This paper presents a new DEPT spectral editing method. Multivariate linear regression was used to analyze the spectra and calculate the best fitting coefficients. The obtained fitting results were then used to calculate DEPT subspectra, yielding separated CH₃, CH₂ and CH signals. The new spectral editing method was shown to perform well on DEPT spectra, especially the complex ones.

Metabonomics analyzes metabolite profiles in living systems and its dynamic responses to changes of endogenous (i.e., physiology and development) and exogenous(i.e., environment and xenobiotics) factors. Pattern recognition plays an important role in data-processing in metabonomic. L₁-norm support vector machine (L₁-norm SVM) is an accurate and robust method in pattern recognition, but not widely used in metabonomics. In this study, we used L₁-norm SVM to analyze metabonomic data obtained from mice infected by schistosomiasis. It was shown that L₁-norm SVM had better performance than
orthogonal partial least squares (O-PLS) in terms of clustering and feature selection. The results also showed that support vector machines have great potential and prospects for data-processing in metabonomics.

Based on multi-frequency shift, a novel technology was proposed for controlling gradient amplifier in magnetic resonance imaging. Phase-locked-loop (PLL) circuit was used to achieve phase shift, and insulated-gate bipolar transistor (IGBT) full-bridge to achieve parallel output current and output power inductor. An output negative feedback system and average current control on every bridge were used to achieve high power, low ripple and low noise current output for the amplifier. The technology was validated on a custom-made gradient amplifier.

Inclusion complex of β-cyclodextrin (β-CD) and D-camphor was prepared from saturated solution with stirring. The stoichiometric ratio of the inclusion complex was found to be 1∶1, as indicated by the 1H NMR results. XRD and FTIR spectroscopy was used to probe the intermolecular interactions between D-camphor and β-CD. 1H ROESY NMR results showed that the bicyclo[2.2.1]-2-heptanone of D-camphor was located in the cavity of β-CD, and its methyl group was partially outside. Quantum chemical calculation was used to obtain minimized binding energy and optimized structure, suggesting the
presence of hydrogen bonding.

Using analgesic dihydroetophine (compound 1) as the example, the stereochemical structures of thebaine derivatives were studied by NMR spectroscopy.
Multiple-frequency selective excitation double pulsed field gradient spin echo 1D NOESY experiments in combination with 2D NMR techniques were used to assign the severely overlapped ¹H and ¹³C resonances from compound 1. According to results of 1D NOESY experiments and the coupling constants measured, the conformational property and C-7 configuration of compound 1 in deuteriochloroform solution were elucidated.

(25S)-27-hydroxypenogenin-3β-O-α-L-rhamnopyranosyl-(1→4)-[O-α-L-rhamnopyranosyl-(1→2)]-O-β-D-glucopyranoside (1) and polyphylloside III (2) were isolated from Trillium tschonoskii by column chromatography. One-dimensional and two-dimensional NMR techniques, including ¹H NMR, ¹³C NMR, DEPT, HSQC, HMBC and ¹H-¹H COSY, were used to elucidate the structures of these compounds. ¹³C NMR and ¹H NMR chemical shifts of the two compounds were completely assigned.

In this paper, we report the use of ³¹P NMR to monitor the synthesis process of 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP). ³¹P NMR was used to detect signals from the residues of key intermediates phosphorous acid and 3. The synthesis process was optimized based on the ³¹P NMR results. Impurity such as PCl₃ were analyzed.

Magic-angle-spinning (MAS) solid-state NMR studies of biomolecules involve application of rapid sample rotation and radiofrequency pulsing, both of which can increase the sample temperature significantly, causing distorted spectra, sample dehydration and even sample degradation. In this review, the mechanisms leading to bio-sample heating in MAS solid-state NMR experiments are first introduced. The importance of sample temperature monitoring is then emphasized. Finally, we present the methods that can be used to to alleviate the problem, including optimization of sample preparation, selecting
optimal NMR parameters, and improving NMR spectrometer hardware such as the probes.