Inferences of SPECT renal dynamic imaging injection quality based on lung and abdominal aorta imaging features.

OBJECTIVE: To analyze the characteristics of blood flow perfusion images at different injection levels to establish an evaluation standard for renal dynamic imaging injection quality and reduce misdiagnosis. METHODS: Data from 140 single-photon emission computed tomography renal dynamic imaging, collected in our hospital, were retrospectively analyzed. The scans were divided into four groups according to the injection quality: total leakage of the imaging agent (group A), partial leakage (group B), poor bolus injection quality (group C), and good bolus injection quality (group D). The time of appearance and regression of the pulmonary blood perfusion phase, the peak time in the abdominal aorta, and the ratio between peak count and actual drug injection count were analyzed. The renal dynamic imaging was repeated in low-quality examinations, and the comparison between the two exams provided the misdiagnosis rate caused by inadequate injections. RESULTS: The images of the lungs and abdominal aorta in group A were blurred and indistinguishable; thus, these exams were unreliable. Both appearance and fading time of the bilateral lung shadows were significantly different between groups B, C, and D (p = 0.002 and p = 0.003, respectively). The peak time and peak counting ratio in the abdominal aorta were also significantly different between these groups (p = 0.002 and p < 0.001, respectively). The misdiagnosis rates of renal dynamic imaging in groups A, B, and C due to the different injection levels were significantly different at 94.29%, 77.14%, and 18.29%, respectively. CONCLUSIONS: The times of appearance and regression of the lung shadows and the peak time and peak count ratio in the abdominal aorta in the dynamic renal imaging perfusion phase can help assess the imaging agent injection quality and identify the need for a repeated examination. Improving the imaging agent injection quality can effectively reduce the renal function misdiagnosis rate.

Cu-Doped P2-Na0.7Mn0.9Cu0.1O2 Sodium-Ion Battery Cathode with Enhanced Electrochemical Performance: Insight from Water Sensitivity and Surface Mn(II) Formation Studies.

Sodium-ion batteries (SIBs) show great application prospects in large-scale energy storage. P2-type manganese-based layered oxides have received special attention by virtue of their high theoretical capacity, low cost, and environmental friendliness. However, water sensitivity and limited cycling stability hinder their application, especially since the underlying mechanisms for the above two issues are still unclear. In this work, copper substitution is used to suppress the Jahn-Teller effect of Mn3+ and affect the corresponding lattice structure. The water sensitivity and charge compensation mechanism were carefully investigated. Results demonstrate that water sensitivity of the electrode is related to the order of Na+/vacancy in the Na interlayers since water molecules are more easily inserted into the charged state electrodes, but the tendency for the water uptake does not increase with Na+ extraction. Furthermore, Mn2+ forms on the surface of electrodes in the initial discharge process, and the redox reaction in the bulk is predominantly between Mn3+ and Mn4+. Cu-substituted in TM layer affects the arrangement of Na+/vacancy and suppresses the Mn2+ formation on the Na0.7Mn0.9Cu0.1O2 electrode that results in superior air stability and better storage properties.

Unveiling the benefits of potassium doping on the structural integrity of Li-Mn-rich layered oxides during prolonged cycling by dual-mode EPR spectroscopy.

The oxygen redox process in Li- and Mn-rich layered oxides will inevitably lead to the generation of oxygen vacancies on the surface and their subsequent injection into the bulk lattice, which incurs poor kinetics, capacity decrease, and voltage fading. Herein, this predicament is effectively alleviated by bulk doping of K+, which is intrinsically stable in the lattice to inhibit the generation of oxygen vacancies in the deep delithiated state. More importantly, the benefits of K+ doping on the structural reversibility during prolonged cycling were studied by electron paramagnetic resonance (EPR) spectroscopy in both perpendicular and parallel polarization modes and high-resolution transmission electron microscopy. The results elucidate that the migration of transition-metal ions and oxygen vacancies and the reduction of Mn-ions are mitigated after K+ doping. Consequently, the growth of Li-poor nanovoids in the bulk lattice is greatly diminished and the structural transition from layered to spinel phases is effectively delayed.