Fibrils of intrinsically disordered protein α-synuclein (α-syn) are hallmarks of Parkinson's disease. Electrostatic interactions are known to contribute significantly on α-syn aggregation. Here we studied how α-syn conformation and fibrillation were affected by changing the net charge of the protein via acetylation of lysine side chains. NMR spectroscopy results showed that lysine-acetylated α-syn remained disordered, and showed a more extended conformation, relative to wild-type protein. Acetylation inhibited α-syn fibrillation, revealed by thioflavin (ThT) fluorescence assay. The N- and C-terminals of the acetylated protein were highly negative charged, causing increased exposure of the non-amyloid-β component (NAC) region. It is proposed that, with the charge distribution in the acetylated protein, electrostatic repulsion, instead of hydrophobic effect, may contribute predominately to the aggregation. This charge-effect mechanism may constitute a new strategy to inhibit α-syn fibrillation.

The ¹³C centerband-only-detection-of-exchange (CODEX) variable-temperature solid-state NMR (SSNMR) technique was used to investigate the evolution of segmental dynamics in poly (vinyl phenol) (PVPh)/poly (ethylene oxide) (PEO) polymer blend within a wide range of temperatures. It was found that the glass transition began with the emergence of remarkable slow motions of the PVPh backbone segments, and ended when the CODEX signal intensity of segmental slow motion reached maximum. The SSNMR results revealed, at molecular level, that the onset and endpoint of conventional calorimetric glass transition are closely associated with the evolution of slow motions in this polymer blend.

Dating ballpoint pen hand-writings is a hot topic in forensic science. It remains untested whether NMR spectroscopy is suitable for this task. In this study, six types of oily ballpoint pen ink were characterized by ¹H NMR spectroscopy. The same method was also used to measure the changes of 2-phenoxyethanol content in oily ballpoint pen hand-writings with aging. A standard curve was established based on the experimental results. It was demonstrated that, as long as the brand of the oily ballpoint pen used was known, hand-writings made within 4 months could be dated precisely. The effects of artificial aging and natural aging were compared subsequently. It was found that ten minutes in ultraviolet aging box corresponded to approximately one day of natural aging.

Brown adipose tissue (BAT) plays a vital role in energy metabolism, and has been regarded as a novel potential drug target for treating obesity. However, the metabolic compositions of BAT and white adipose tissue (WAT) remain to be determined. We applied nuclear magnetic resonance (NMR) and gas chromatography (GC) based metabonomics approaches to characterize and compare the composition of water-soluble metabolites and fatty acids in BAT and WAT. The results indicated that these two types of adipose tissue have marked differences in carbohydrate metabolism, amino acid metabolism, fatty acids metabolism, nucleotide metabolism and choline metabolism pathways, and these differences are tightly associated with their unique biological functions. Our research provided clues and basic information for elucidation of the function of BAT at molecular level.

Tuberculosis (TB) is the second largest infectious disease caused by a single pathogen leading to mortality, only after AIDS. Discovery of biomarkers associated with disease progression is vital for TB screening and control. Metabonomics is among the most useful tools for this purpose. A few metabonomic studies on TB patients have been published. In this study, the plasma samples of TB patients with varying severity were studied by ¹H NMR based metabonomics. Orthogonal partial least squares-discriminant analysis (OPLS-DA) models showed that TB patients at different stages and healthy controls could be differentiated by their plasma metabolic profiles. It was found that the TB groups had significantly higher levels of valine, alanine, creatine, and 3-hydroxybutyrate, relative to the healthy controls. In the TB patients, the levels of lactate, pyruvate, N-acetyl glycoprotein, leucine and glutamate increased gradually with disease progression, while the level of citrate, a tricarboxylic acid (TCA) cycle intermediate, decreased with disease progression. The plasma metabolic profile changes indicated increased energy metabolism and glycolysis, enhanced ketogenesis of fatty acid, reduced TCA cycle, and disordered amino acid metabolism in the TB patients.

With advances in population aging, age-related diseases have become a global problem. Neurodegenerative disease is one type of leading aging associated diseases, the mechanism of which remains elusive. In the present study, ³¹P NMR spectroscopy was used to characterize alterations of small molecules in rat brain for different age group, and identify alterations of energy associated phosphorylated compounds with aging, which will be helpful for interpreting age-related metabolism in brain. Results showed that energy related metabolite phosphocreatine increased significantly, whereas phosphatidylcholine and phosphorylcholine reduced significantly in aged rat brain. Interestingly, glucose phosphates appeared in aged rat brain. This study demonstrated the alterations of phospholipid metabolism in rat brain with aging, which may help to understand the development of neurodegeneration, and these metabolites may be used as molecular markers for monitoring neurodegenerative disorders.

Sensitivity enhancement is an everlasting topic in analytical chemistry, for which the two most common approaches are signal enhancing and noise suppressing. In nuclear magnetic resonance (NMR) spectroscopy, signal enhancement can be achieved by utilizing high field spectrometers, cryogenic probes and/or using sophisticated pulse sequences. However, these approaches are often associated with dramatically increased cost. The other way to enhance sensitivity is to de-noise the data by post-processing, which is obviously more cost-effective and attractive. Based on the statistical resampling principle, we previously developed an NMR data post-processing method named NASR (An Effective Approach for Simultaneous Noise and Artifact Suppression in NMR Spectroscopy), which is effective to reduce unwanted noises and suppress artifacts in one-dimensional and multiple-dimensional NMR experiments. In practice, however, the optimal parameter setting for NASR is often difficult to achieve. In this study, compressed sensing (CS) was incorporated into the original NASR approach, resulting in a novel and robust noise suppression method for NMR experiments (CS_NASR), in which the subjective factors of the handlers are negligible.

Under-sampled k-space data can be used to reconstruct high-quality images with compressed sensing (CS) algorithms, greatly improving the imaging speed. However, the traditional CS reconstruction is time-consuming, and this drawback constitutes a major obstacle to the routine clinical applications of CS-MRI. To reduce the total reconstruction time, we proposed here a synchronized CS scan-reconstruction scheme. In the scheme, reconstruction is carried out while the scan is still in process, such that the reconstructed images can be displayed in real-time, and the operator can terminate the scan as he/she wishes when the quality of the images acquired so far is deemed sufficient for his/her needs. The classic variable density random sampling strategy used for traditional CS reconstruction needs to be modified, since in this scheme the final sampling pattern remains unknown before the termination of the scan. In this paper, we developed an under-sampling strategy to meet the requirements of synchronized CS scan-reconstruction, in which different probability density functions (PDFs) are used for random sampling at different phases. Experimental results demonstrated that, compared to the single-PDF approach, a two-phase sampling strategy provided better reconstruction quality in the whole scan-reconstruction process.

In this study, we aimed to study the relationship between structural characteristics of the arcuate fasciculus (AF) derived from diffusion MRI and the performance of language comprehension. Constrained spherical deconvolution and tractography were used to analyze the diffusion MRI data. A total of 14 right-handed subjects with brain tumors in the left-hemisphere were recruited. Two MRI scan which one before the tumor-removing brain surgery and the other after the surgery were performed. In each scan, a short version of Boston diagnostic aphasia Examination (BDAE) test was applied to evaluate the performance of language comprehension. Four averaged diffusion indices along bilateral AF reconstructed by tractography were extrocted. The results showed that FA and RD in the left AF changed significantly (p<0.01) after the surgery, but similar changes were not found in the right AF. Diffusion indices of the left AF tract showed significantly higher (p<0.01) correlation with the BDAE results (r=0.6~0.8), relative to the right AF (r=0.3~0.4). The findings are consistent with previous reports concerning the functional lateralization of the AF.

Compared to their parent forms of bases or acids, drugs in the form of salts have improved solubility, chemical stability, and capability for recrystallization. For the drug cytidine hydrochloride, whether the protonation position is at N-3 or NH₂ remains unclear, and X-ray crystallography cannot provide this information. In this study, ¹H and ¹³C NMR spectroscopy was used to study the exact protonation position in cytidine hydrochloride. It was shown clearly by chemical shift changes that the protonation position is at N-3 rather than NH₂. It was further confirmed that the chemical bond between C-4 and NH₂ in cytidine salts has double bond-like properties.

Spectral line profile distortion, resulted from self-absorption of rubidium atoms in the rubidium spectral lamp bulb, is detrimental to the frequency stability of rubidium frequency standard. In this study, the hyperfine spectral profiles of rubidium lamps were studied with an F-P interferometer, and the influence of the type and pressure of buffer gas, lamp operating temperature and radio frequency-excitation power on self-absorption was examined. The results showed that the lamps filled with Ar gas or Kr gas showed serious self-absorption, while Xe-filled lamps had less self-absorption. Self-absorption could also be reduced by either sufficiently decreasing the operating temperature or increasing the pressure of buffer gas and rf-excitation power of the lamp.

The mechanical properties and dimensional stability of wood are influenced by moisture sorption. Understanding changes of the state of water during wood sorption has great significance. In this study, the state and relaxation property of water in American yellow poplar and red oak during the sorption process were investigated by time-domain nuclear magnetic resonance (TD-NMR). It was found that, in both species, the peak area of bound water increased rapidly during the first 4 hours of the sorption process, while the peak area of free water showed no obvious change. These results suggested that water amount increases in the early sorption stage could mainly be attributed to bound water. Under the equilibrium condition of moisture sorption, the peak area of free water in red oak doubled that in American yellow poplar, likely due to the pore aperture of former is bigger than the later, providing more space for absorbed free water. It was also observed that the amount and rate of free water sorption were higher in red oak than in American yellow poplar.

Fully-opened unilateral nuclear magnetic resonance (NMR) systems are portable and low in cost, and thus a useful tool for in situ, real-time and nondestructive testing. The paper reviews the development of unconventional NMR, especially fully-opened unilateral NMR. The hardware structure of NMR-MOUSE developed by Professor Bernhard Blümich in RWTH Aachen University was discussed in detail, as well as the measurement methods. The applications of unilateral NMR were also introduced.

Two novel daidzein[1,3] oxazine derivatives were synthesized by a one-pot approach using daidzein, n-butyl amine and 37% aqueous solution of formaldehyde as the raw materials under ultrasonic radiation. The ¹H and ¹³C NMR chemical shifts of the title compounds were assigned by two-dimensional NMR techniques, including DEPT, ¹H-¹H COSY, ¹H-¹³C HSQC and ¹H-¹³C HMBC. The reactive sites in daidzein were determined.

The spectral data of peptidomimetics cyclo[-RGD-ψ(triazole)-GD-] were reported, including UV, FT-IR and NMR (i.e., ¹H NMR, ¹H-¹H COSY, ¹³C NMR, DEPT, ¹H-¹³C HSQC and ¹H-¹³C HMBC). The NMR signals were assigned. The infrared spectrum was analyzed to derive the types of vibrations of the functional groups in the compound. The molecular structure of peptidomimetics cyclo[-RGD-ψ(triazole)-GD-] was determined.

Cycloaddition reaction of C₆₀ with rosin compounds produces many functional fullerene derivatives. ¹H and ¹³C NMR spectra of the target compound N,N-tetrachlorophthaloyl-13-nitro-7,7-C₆₀-deisopropyldehydroabietylamine were collected and analyzed. The ¹H and ¹³C chemical shifts were assigned using two-dimensional NMR techniques, including ¹H-¹H COSY, ¹H-¹H ROESY, ¹H-¹³C HSQC and ¹H-¹³C HMBC. The spectral data obtained provided a reference for structure characterization of analogous compounds.

Lomustine is an important drug having chiral carbon atoms. In the present study, one-dimensional ¹H and ¹³C NMR, as well as two-dimensional techniques (i.e., ¹H-¹³C HMBC, ¹H-¹³C HSQC, ¹H-¹H COSY and ¹H-¹H NOESY) were used to elucidate the structure of Lomustine. The proton and carbon chemical shifts of the compound were assigned.