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Based on the principle of birdcage coil and the decoupling theory of array coil, a design scheme for dual-nuclear magnetic resonance imaging (MRI) coil is proposed. A LC parallel trap is used to improve the adaptability of the inductive decoupling scheme. According to the design scheme and simulation, a 1H/31P dual-nuclear parallel MRI coil is fabricated for a 4.7 T system. Dual-nuclear parallel imaging experiments are carried out on a custom-built MRI system to verify the feasibility of the coil design.

D-T2 two-dimensional nuclear magnetic resonance (2D NMR) logging technology can distinguish pore fluid types intuitively; it is widely used in oil and gas exploration. Many 2D NMR inversion methods have been proposed thus far, but most of them are limited to numerical simulation. It is necessary to study the applicability of different inversion methods for NMR logging data of various acquisition sequences and to select optimal inversion methods for the 2D NMR logging software module. In this work, the principle of 2D NMR logging is studied; truncated singular value decomposition (TSVD), BRD, LM-norm smoothing, and TIST-L1 regularization methods are also studied in detail; and the precision and computational efficiencies of CPMG and diffusion editing (DE) sequences obtained from oil—water and gas—water models are compared, respectively. The inversion results and calculation time of TSVD, BRD, LM-norm smoothing, and TIST-L1 regularization are compared and analyzed through numerical simulation, and the inversion method is optimized to process the SP mode logging data from the MR Scanner instrument. The results show that the TIST-regularization method and LM-norm smoothing method are more accurate for the CPMG and DE sequence echo trains of the oil-water and gas-water models, but the LM-norm smoothing method is less time-consuming, making it more suitable for logging data processing. A case study in well A25 shows that the LM-norm smoothing method produces results consistent with GEOLOG software, demonstrating that the LM-norm smoothing method is applicable in practical NMR logging processing. [ABSTRACT FROM AUTHOR]

A high level of oxidized low-density lipoproteins (oxLDLs) is an independent risk factor for cardiovascular disease. The aim of the present study was to investigate whether insulin-like growth factor-1 (IGF-1) protected endothelial progenitor cells (EPCs) from injury caused by ox-LDLs, and whether the endothelial nitric oxide synthase (eNOS)/nitric oxide (NO) pathway was involved in this process. EPCs were isolated from human peripheral blood and characterized. In order to evaluate the effect of IGF-1 on EPCs, cells were incubated with ox-LDLs (100 mg/ml) for 24 h to induce a model of EPC dysfunction in vitro, which demonstrated a decrease in the number of EPCs, concomitant with increased apoptosis and decreased proliferation rates. IGF-1 dose-dependently increased the number of EPCs. Concurrently, IGF-1 decreased the levels of apoptosis of EPCs and improved EPCs proliferation following ox-LDLs challenge. In addition, IGF-1 significantly increased NO levels in ox-LDLs-treated EPCs, accompanied by an upregulation in eNOS expression. The protective effects of IGF-1 on EPCs and NO production were abolished by L-NAME, a specific eNOS inhibitor. These results suggested that IGF-1 protects EPCs from dysfunction induced by oxLDLs through a mechanism involving the eNOS/NO pathway. [ABSTRACT FROM AUTHOR]

The Radar Cross Section (RCS) prediction for cavities is significant to measure a target's radar detection ability. For electrically large, deep, arbitrary shaped cavities, this paper presents a hybrid algorithm based parallel solution using Message Passing Interface on distributed memory computers. The meaning of 'Hybrid' here is threefold. First, the RCS for cavities is modeled and calculated with a hybrid algorithm of IPO (Iterative Physical Optics), FMM (Fast Multipole Method) and Generalized Reciprocit Integral (GRI) combined by a cascading segmentation technique. Second, a hybrid approach is applied to the two phases of parallelization. On phase of geometrical preprocessing, all parallel processes assume a whole workload to construct the cavity geometry independently. On the other phase of electromagnetic computing, the workload is distributed by domain decomposition. Third, the decomposition scheme is hybrid as facets are decomposed to compute near-field interation while angle samples are used to distribute far-field interaction. The superposition of electromagnetic measures and permutability of math vector operations are fully exploited to do partial computation in order to minimize the communication overhead. The hybrid parallel solution can achieve very good tradeoff between memory and time. It yields a good load balance while still keeping the parallel code pretty concise. Numerical results show near-linear scalability and over 90% parallel efficiency. [ABSTRACT FROM AUTHOR]