Novel ^99mTc(III) Complexes [^99mTcCl(CDO)(CDOH)₂B–R] (CDOH₂ = Cyclohexanedione Dioxime) Useful as Radiotracers for Heart Imaging

In this study, we evaluated seven new ^99mTc­(III) complexes [^99mTcCl­(CDO)­(CDOH)₂B–R] (^99mTc–2Fboroxime: R = 2-formylfuran-3-yl (2F); ^99mTc–3Fboroxime: R = furan-3-yl (3F); ^99mTc–5Fboroxime: R = 5-formyfuran-2-yl (5F); ^99mTc–HPboroxime: R = 6-hydroxylpyridin-2-yl (HP); ^99mTc–MPYboroxime: R = 5-methoxypyridin-3-yl (MPY); ^99mTc–PMboroxime: R = 1,5-pyrimidin-3-yl (PM); and ^99mTc–4PYboroxime: R = pyridin-4-yl (4PY)) for their potential as heart imaging agents. All new ^99mTc­(III) radiotracers except ^99mTc–2Fboroxime were prepared with high radiochemical purity (RCP > 95%). The low RCP (∼75%) for ^99mTc–2Fboroxime is most likely caused by steric hindrance from the 3-formyl group. Biodistribution and imaging studies were performed in SD rats. Planar image quantification was performed to compare their myocardial retention times. We found that the myocardial washout curves of new ^99mTc­(III) radiotracers were best fitted the biexponential decay function. The AUC (area under the curve) values followed the general trend: ^99mTc–5Fboroxime (129 ± 6) > ^99mTc–3Fboroxime (114 ± 11) > ^99mTc–Teboroxime (104 ± 16) > ^99mTc–MPYboroxime (92 ± 18) > ^99mTc–4PYboroxime (77 ± 10) > ^99mTc–PMboroxime (68 ± 14) ≈ ^99mTc–HPboroxime (62 ± 14). The 2 min heart uptake values from biodistribution studies follow the ranking order of ^99mTc–5Fboroxime (3.75 ± 0.15%ID/g) ≈ ^99mTc–MPYboroxime (3.73 ± 0.24%ID/g) > ^99mTc–PMboroxime (3.47 ± 0.15%ID/g) ≈ ^99mTc–3Fboroxime ≈ (3.25 ± 0.77%ID/g). The 5 min heart uptake of ^99mTc–5Fboroxime (3.91 ± 0.09%ID/g) was almost identical to its 2 min heart uptake (3.75 ± 0.15%ID/g), and its 15 min heart uptake value (2.83 ± 0.08%ID/g) compared well to the 2 min heart uptake of ^99mTc–Teboroxime (3.00 ± 0.37%ID/g). It took ∼5 min for ^99mTc–5Fboroxime to approach the 1 min heart uptake value of ^99mTc–Teboroxime (∼3.5% ID/g) and ∼9.5 min to reach the 2 min heart uptake value of ^99mTc–Teboroxime (∼3.0% ID/g). The best image acquisition window is 0–5 min for ^99mTc–5Fboroxime. High-quality single-photon emission computed tomography images of the rat hearts were acquired in any of the 5 min window over the first 20 min after its administration. ^99mTc–5Fboroxime has significant advantages over ^99mTc–Teboroxime as the radiotracer for myocardial perfusion imaging

Supplemental Material: Molybdenum isotopes in mafic igneous rocks record slab-mantle interactions from subarc to postarc depths

Methods, data, and supplemental figures. </p

Keywords of the 2010 Gulf of Mexico oil spill by degree and weighted degree.

<p>Keywords of the 2010 Gulf of Mexico oil spill by degree and weighted degree.</p

News Media Distribution of the two trending events.

<p>News Media Distribution of the two trending events.</p

Community networks about the two trending events.

<p>Community networks about the two trending events.</p

Visualization results of the whole-sample words networks of the two trending events.

<p>Visualization results of the whole-sample words networks of the two trending events.</p

Visualization results of the monthly-words networks of the two trending events.

<p>Visualization results of the monthly-words networks of the two trending events.</p

An Approach To Enhance the CO₂ Tolerance of Fluorite–Perovskite Dual-Phase Oxygen-Transporting Membrane

Most of the alkaline earth-containing perovskite-based oxygen-transporting membranes (OTMs) have insufficient tolerance toward CO₂ that potentially limits their commercial applications, for example, oxy-fuel combustion processes with CO₂ capture. One concern regarding the chemical potential of oxygen that may influence the CO₂ tolerance of perovskites, however, is lacking effective investigations. In the present work, we demonstrate that the approach to increase the chemical potential of oxygen at the feed side contributes to stabilize the oxygen permeation fluxes of the fluorite–perovskite dual-phase OTM under CO₂-rich atmosphere, and we further verify that oxygen can effectively act as a “buffer” to prevent the carbonate formation. Remarkably, we achieve high and stable oxygen permeation fluxes over 0.84 mL cm^–2 min^–1 during long-term operation at 900 °C with a 0.5 mm thickness 80 wt % Ce_0.8Gd_0.15Cu_0.05O_2−δ-20 wt % SrFeO_3−δ (CGCO-SFO, nominal composition) dual-phase membrane using oxygen-enriched air as the feed gas and pure CO₂ as the sweep gas

The evolution of the quantity of news after the events occurred.

<p>The evolution of the quantity of news after the events occurred.</p

Evolution of nodes and the average degree and the average weighted degree of monthly-words networks about the two trending events.

<p>Evolution of nodes and the average degree and the average weighted degree of monthly-words networks about the two trending events.</p