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51.
Tropp J Lupo JM Chen A Calderon P McCune D Grafendorfer T Ozturk-Isik E Larson PE Hu S Yen YF Robb F Bok R Schulte R Xu D Hurd R Vigneron D Nelson S 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2011,208(1):171-177
We report metabolic images of (13)C, following injection of a bolus of hyperpolarized [1-(13)C] pyruvate in a live rat. The data were acquired on a clinical scanner, using custom coils for volume transmission and array reception. Proton blocking of all carbon resonators enabled proton anatomic imaging with the system body coil, to allow for registration of anatomic and metabolic images, for which good correlation was achieved, with some anatomic features (kidney and heart) clearly visible in a carbon image, without reference to the corresponding proton image. Parallel imaging with sensitivity encoding was used to increase the spatial resolution in the SI direction of the rat. The signal to noise ratio in was in some instances unexpectedly high in the parallel images; variability of the polarization among different trials, plus partial volume effects, are noted as a possible cause of this. 相似文献
52.
Quality assurance and quality control for thermal/optical analysis of aerosol samples for organic and elemental carbon 总被引:1,自引:0,他引:1
Chow JC Watson JG Robles J Wang X Chen LW Trimble DL Kohl SD Tropp RJ Fung KK 《Analytical and bioanalytical chemistry》2011,401(10):3141-3152
Accurate, precise, and valid organic and elemental carbon (OC and EC, respectively) measurements require more effort than
the routine analysis of ambient aerosol and source samples. This paper documents the quality assurance (QA) and quality control
(QC) procedures that should be implemented to ensure consistency of OC and EC measurements. Prior to field sampling, the appropriate
filter substrate must be selected and tested for sampling effectiveness. Unexposed filters are pre-fired to remove contaminants
and acceptance tested. After sampling, filters must be stored in the laboratory in clean, labeled containers under refrigeration
(<4 °C) to minimize loss of semi-volatile OC. QA activities include participation in laboratory accreditation programs, external
system audits, and interlaboratory comparisons. For thermal/optical carbon analyses, periodic QC tests include calibration
of the flame ionization detector with different types of carbon standards, thermogram inspection, replicate analyses, quantification
of trace oxygen concentrations (<100 ppmv) in the helium atmosphere, and calibration of the sample temperature sensor. These
established QA/QC procedures are applicable to aerosol sampling and analysis for carbon and other chemical components. 相似文献