A TEM study of morphological and structural degradation phenomena in LiFePO₄-CB cathodes:Morphological and structural degradation in LiFePO4-CB cathodes

LiFePO4-based cathodes suffer from various degradation mechanisms which influences the battery performance. In this paper morphological and structural degradation phenomena in laboratory cathodes made of LiFePO4 (LFP) mixed with carbon black (CB) in an 1 mol L-1 LiPF6 in EC:DMC (1:1 by weight) electrolyte are investigated by transmission electron microscopy (TEM) at various preparation, assembling, storage and cycling stages. High-resolution TEM (HRTEM) imaging shows that continuous SEI layers are formed on the LFP particles and that both storage and cycling affects the formation. Additionally loss of CB crystallinity, CB aggregation and agglomeration is observed. Charge-discharge curves and impedance spectra measured during cycling confirm that these degradation mechanisms reduce the cathode conductivity and capacity.Comment: 5 figures, 2 table, journal article in International Journal of Energy Research, 201

Imaging of treatment response to the combination of carboplatin and paclitaxel in human ovarian cancer xenograft tumors in mice using FDG and FLT PET

A combination of carboplatin and paclitaxel is often used as first line chemotherapy for treatment of ovarian cancer. Therefore the use of imaging biomarkers early after initiation of treatment to determine treatment sensitivity would be valuable in order to identify responders from non-responders. In this study we describe the non-invasive PET imaging of glucose uptake and cell proliferation using 2-deoxy-2-[(18)F]fluoro-D-glucose (FDG) and 3'-deoxy-3'-[(18)F]fluorothymidine (FLT) for early assessment of treatment response in a pre-clinical mouse model of human ovarian cancer treated with carboplatin and paclitaxel.In vivo uptake of FLT and FDG in human ovarian cancer xenografts in mice (A2780) was determined before treatment with carboplatin and paclitaxel (CaP) and repeated day 1, 4 and 8 after treatment start. Tracer uptake was quantified using small animal PET/CT. Tracer uptake was compared with gene expression of Ki67, TK1, GLUT1, HK1 and HK2.Tumors in the CaP group was significantly smaller than in the control group (p=0.03) on day 8. On day 4 FDG SUVmax ratio was significantly lower in the CaP group compared to the control group (105 ± 4% vs 138 ± 9%; p=0.002) and on day 8 the FDG SUVmax ratio was lower in the CaP compared to the control group (125 ± 13% vs 167 ± 13%; p=0.05). On day 1 the uptake of FLT SUVmax ratio was 89 ± 9% in the CaP group and 109 ± 6% in the control group; however the difference was not statistically significant (p=0.08).Our data suggest that both FDG and FLT PET may be used for the assessment of anti-tumor effects of a combination of carboplatin and paclitaxel in the treatment of ovarian cancer. FLT provides an early and transient signal and FDG a later and more prolonged response. This underscores the importance of optimal timing between treatment and FLT or FDG imaging since treatment response may otherwise be overlooked

Early Detection of Response to Experimental Chemotherapeutic Top216 with [18F]FLT and [18F]FDG PET in Human Ovary Cancer Xenografts in Mice

BACKGROUND: 3'-Deoxy-3'-[(18)F]fluorothymidine ((18)F-FLT) is a tracer used to assess cell proliferation in vivo. The aim of the study was to use (18)F-FLT positron emission tomography (PET) to study treatment responses to a new anti-cancer compound. To do so, we studied early anti-proliferative effects of the experimental chemotherapy Top216 non-invasively by PET. METHODOLOGY/PRINCIPAL FINDINGS: In vivo uptake of (18)F-FLT in human ovary cancer xenografts in mice (A2780) was studied at various time points after Top216 treatment (50 mg/kg i.v. at 0 and 48 hours) was initiated. Baseline (18)F-FLT scans were made before either Top216 (n = 7-10) or vehicle (n = 5-7) was injected and repeated after 2 and 6 hours and 1 and 5 days of treatment. A parallel study was made with 2'-deoxy-2'-[(18)F]fluoro-D-glucose ((18)F-FDG) (n = 8). Tracer uptake was quantified using small animal PET/CT. Imaging results were validated by tumor volume changes and gene-expression of Ki67 and TK1. Top216 (50 mg/kg 0 and 48 hours) inhibited the growth of the A2780 tumor compared to the control group (P<0.001). (18)F-FLT uptake decreased significantly at 2 hours (-52%; P<0.001), 6 hours (-49%; P = 0.002) and Day 1 (-47%; P<0.001) after Top216 treatment. At Day 5 (18)F-FLT uptake was comparable to uptake in the control group. Uptake of (18)F-FLT was unchanged in the control group during the experiment. In the treatment group, uptake of (18)F-FDG was significantly decreased at 6 hours (-21%; P = 0.003), Day 1 (-29%; P<0.001) and Day 5 (-19%; P = 0.05) compared to baseline. CONCLUSIONS/SIGNIFICANCE: One injection with Top216 initiated a fast and significant decrease in cell-proliferation assessable by (18)F-FLT after 2 hours. The early reductions in tumor cell proliferation preceded changes in tumor size. Our data indicate that (18)F-FLT PET is promising for the early non-invasive assessment of chemotherapy effects in both drug development and for tailoring therapy in patients