HSQC experiments are the most basic experiments in protein NMR. In HSQC experiments, water suppression is mainly achieved by a pair of field gradient pulses whose intensity ratio is in accordance with the ratio of the heteronuclear gyromagnetic ratios. In this paper, a simple method is propsed to achieve clean water suppression in HSQC experiments by properly modulating the gradient pulse length.

This study explores the properties of the SiO₂ powders prepared from tetraethyl orthosilicate (TEOS) pre-solution with and without incorporating polyethylene (PEG) of different molecular weights. SiO₂ powders were prepared by the sol-gel method in combination with oven-drying before and after annealing. The hydrolysis and condensation reactions of TEOS pre-solution at pH 3 occur more thoroughly than that at pH 5, 7, and 9. The rate of hydrolysis and
condensation is found to increase with temperature and the molecular weight of PEG for pre-solution and a maximum in the powder yield is reached for TEOS pre-solution at pH 3. The powder prepared from the TEOS pre-solution added with PEG is superior to that without adding PEG, with a higher water adsorption capacity. With the powders annealed at a temperature up to 500 ^oC, the ethanol concentration was found to be increased. In addition, the relation between water adsorption and surface area of SiO₂ powders for purification of ethanol is discussed based on both liquid and solid state nuclear magnetic resonance (NMR) spectroscopies, scanning electron microcopy (SEM) and BET.

Angiogenesis inducing agents, such as Sildenafil, can be used to treat stroke. In this study, USPIO-enhanced MRI was used to visualize collateral vessels in the penumbral area of lesions of rats subjected to transient middle cerebral artery occlusion (tMCAO), and the evaluate efficacy of the Sildenafil treatment. Here, P904, a USPIO agent, was used as a T₁ reducing agent at a low dose for MR angiography and as a T₂* reducing agent at a moderate dose for
visualization of very small vessels on gradient echo susceptibility-weighted imaging (SWI). SWI scans without/with USPIO injection were performed for the following cases: tMCAO without any treatment (n=5), tMCAO with Sildenafil treatment (n=6), and sham tMCAO (n=1) at four different time points (i.e., baseline, 24 h, two weeks and four weeks after tMCAO). The presence of newly developed vessels in the periphery of the ischemic core was only observed in those
animals showing severe ischemic brain damage and at the same time received Sildenafil treatment at two weeks post tMCAO. This work suggests that, at 7 T, high resolution SWI in conjunction with USPIO injection at a moderate dose can be used to visualize post-stroke angiogenesis in the tMCAO rat model.

Automated metabolite quantification with curve fitting is essential for analyzing large amount of in vivo magnetic resonance spectroscopic imaging (MRSI) data. However, such analysis is often hindered by distorted peak lineshapes and baselines normally seen in in vivo MRSI experiments. In the present study, a multiscale approach was utilized for peak-specific automated phase correction in multi-slice MRSI data of human brain. The results suggest that this
novel approach can improve the robustness and efficiency of metabolite quantification and facilitate automated analysis of multi-slice in vivo MRSI data of human brain.

Gliomas are the most common malignant tumors. The lack of detailed information on the progression of gliomas make their clinical diagnosis and treatment a challenging endeavor. In this study, the metabolic profiles of two glioma cell lines (i.e., CHG5 and U87) with different malignancy were analyzed by 1H NMR. The results showed that there were significant differences in the metabolic profiles of these two cell lines. High levels of 15 metabolites including citratate, and lower levels of 6 metabolites including lactate and taurine were found in the CHG5 cell line, compared to the U87 cell line. The
findings of this study suggested that metabolic profiles of glioma cell lines could be associated with their malignant features, thus may potentially be used as a measure in elucidating the molecular mechanisms underlying the progression of gliomas and in the development of non-invasive markers for monitoring of gliomas.

In petroleum exploration, diffusion coefficient measured with NMR techniques is often used to identify fluid types (e.g., oil, water, and gas) and to calculate the saturation degree of reservoir rocks. In the micro-pores, however, the apparent or effective diffusion coefficient must be lower than the free diffusion coefficient. In this paper, the relationship between pore size and apparent diffusion coefficient is simulated using the finite difference and random walk methods. The effects of restricted diffusion on the accuracy of the petrophysical parameter calculations were analyzed under the well-logging and laboratory
conditions. Lastly, the application conditions and advantages of the two simulation methods were discussed.

含芳香环的氨基酸残基多处于蛋白质的疏水内核或者是蛋白质与配体的结合部位，这些残基间的非共价键相互作用对于蛋白质结构的稳定性和生物的特异性识
别有重要意义．因此，在蛋白质的核磁共振研究中，芳香基团被认为是一个研究蛋白质结构动力学的潜在探针．但是由于芳香基团的1H-13C HSQC谱的灵敏度较低，目前，利用核磁共振对其进行研究乏善可陈．造成这一现象的主要原因可能在于芳香环体积较大，往往存在慢的翻转运动，导致其NMR信号被展宽．作者利用CPMG-INEPT HSQC序列可以有效地减小慢运动影响的特征，将其应用到了GB1蛋白质芳香环的¹H-¹³CHSQC谱中，有效的增强了芳香基团HSQC谱信号的灵敏度，得到了部分在常规HSQC中无法观测的信号．

²H NMR and PFG NMR were performed on uniaxially stretched Nafion membrane to evaluate the deformation effects on its morphology and properties. We
conducted a systematic study on Nafion over draw ratio range from 1 to 7. Uniaxial deformation was found to lead a strong alignment of the hydrophilic channel, and enhance the water mobility along the draw direction before reaching the max orientation (L<5). These effects could be used for improving the PEMs´ properties. The deformation after the max orientation (L≥5) led to a decrease of mobility of the water molecules. This stretching effect also led to anisotropic swelling of the membranes in solvent as the channels align along the draw direction. The absorption and mobility of methanol increased as the draw ratio, hindering its application in DMFC.

Indole-3-pyruvic acid is an important α-keto acid in the tryptophan pathway. In this work, two main forms of indole-3-pyruvic acid in acetonitrile and water solutions were studied using multi-dimensional NMR techniques. The results showed that both forms were present, and the enol-form of indole-3-pyruvic acid was the dominant form in acetontrile whereas the keto-form was the main form in water. This work provided detailed assignments for the ¹H and ¹³C NMR signals from both the enol- and keto-forms of indole-3-pyruvic acid, offering essential spectroscopic information for this metabolite.

A frequency synthesizer based on PLL and DDS was designed for high-field NMR spectrometers. An MCU controller with CAN interface is used as the center
processor for the system, which receives instructions from the NMR console and controls the other components to change the power and frequency of the output. The PLL frequency synthesizer is used to get stable and pure signal for mixing, contributing to low phase noise and wide band spanning from 5 to 645 MHz. Combined with DDS, the resolution of the synthesizer can be as high as μHz. This design has many other benefits, including easy control, high precision and low cost.

LmKTT-1a is a dual-functional toxin recently discovered in scorpion venom glands. It has both protease and potassium ion channel inhibiting properties. Preliminary work has determined the solution structure of LmKTT-1a and evaluated its potassium ion channel inhibition function. In this study, NMR techniques and chemical shift perturbation analysis were used to identify the interaction interface between LmKTT-1a and the protease Trypsin. The residues of V10 to F17 in the loop region of LmKTT-1a was found to be the crucial binding sites. The NMR results were confirmed by a serious of mutations and enzymatic assays, and we found that K14 is the most pivotal residue in the interaction between Trypsin and LmKTT-1a. This work helped to further understand the structural-function relationship of LmKTT-1a.

This paper exploits one optimized unitary operator to prepare a type of highly entangled state of multiple qubits—cluster state. Based on optimal control theory, the duration of optimized unitary operator has been shortened due to the application of a series of non-selective pulse. We experimentally implemented the optimized unitary operator on a NMR spectrometer. By firstly generating a pseudo-pure state, a three-qubit cluster state was produced by applying the optimized unitary operator. Our experimental results show the feasibility of the optimized unitary operator.

Magnetic resonance imaging (MRI) is now a routine neuroimaging tool in the clinic. Throughout all phases of stroke from acute to chronic, MRI plays an important role to diagnose, evaluate and monitor the cerebral tissue undergoing stroke. This review provides a description of various MRI methods and an overview of selected MRI studies, with an embolic stroke model of rat, performed in the MRI laboratory of Department of Neurology, Henry Ford Hospital, Detroit, Michigan, US.

Phase images of magnetic resonance imaging (MRI) contain abundant information about local susceptibility changes among different types of tissues, and getting phase images requires no additional scan time. The diagnosis of cerebrovascular diseases and nervous system diseases may benefit from the quantification of paramagnetic substances in tissues. Quantitative susceptibility mapping (QSM), which uses the local phase information, has become a hot topic in basic and clinical studies. Paramagnetic substances in tissues cause local susceptibility changes and lead to local inhomogeneous magnetic field. However, the reconstruction of susceptibility distribution from induced magnetic field is an ill-posed inverse problem, and there are still many problems to be
solved at present. This article focuses on the theory of QSM, reconstruction methods and its applications in MRI.