Effect of solid-electrolyte pellet density on failure of solid-state batteries.

Despite the potentially higher energy density and improved safety of solid-state batteries (SSBs) relative to Li-ion batteries, failure due to Li-filament penetration of the solid electrolyte and subsequent short circuit remains a critical issue. Herein, we show that Li-filament growth is suppressed in solid-electrolyte pellets with a relative density beyond ~95%. Below this threshold value, however, the battery shorts more easily as the density increases due to faster Li-filament growth within the percolating pores in the pellet. The microstructural properties (e.g., pore size, connectivity, porosity, and tortuosity) of [Formula: see text] with various relative densities are quantified using focused ion beam-scanning electron microscopy tomography and permeability tests. Furthermore, modeling results provide details on the Li-filament growth inside pores ranging from 0.2 to 2 µm in size. Our findings improve the understanding of the failure modes of SSBs and provide guidelines for the design of dendrite-free SSBs.

Oxaliplatin-mediated inhibition of survivin increases sensitivity of head and neck squamous cell carcinoma cell lines to paclitaxel.

The present study deals with the evaluation of the efficacy of oxaliplatin and paclitaxel combination as a potential strategy in controlling HNSCC cell proliferation and the assessment of correlation between occurrence of apoptosis and changes in expression of survivin (IAP). The panel cell lines included two HNSCC cell lines (Cal27 and NT8e) and one normal cell line (293) with differential level of survivin expression in accordance with chemosensitivity. The cytotoxicity and effect of drugs on apoptosis was determined, separately and in combination. Combined treatment of cells with paclitaxel and oxaliplatin resulted in significantly higher cytotoxicity as compared to individual single drug treatment. Cytotoxicity was prominent in paclitaxel to oxaliplatin (pacl-oxal) sequence treatment with an approximate two-fold increase in apoptosis as compared to oxaliplatin to paclitaxel (oxal-pacl) sequence treatment. Paclitaxel treatment also caused increased survivin expression showing reduced apoptosis at low concentration. Oxaliplatin, when combined with paclitaxel, decreased the survivin level with increased cell death. Inhibition of survivin by a small interfering RNA (siRNA) method also increased the sensitivity of the cancer cell lines to paclitaxel whereas over-expression of survivin in the transfected 293-cell line provided resistance. In conclusion, the interaction between drugs was synergistic and schedule-dependent. Survivin played a critical role in paclitaxel resistance through the suppression of apoptosis, and a significant induction of apoptosis was observed when oxaliplatin was combined with paclitaxel at least in part by the down-regulation of survivin.

p38-mediated regulation of an Fas-associated death domain protein-independent pathway leading to caspase-8 activation during TGFbeta-induced apoptosis in human Burkitt lymphoma B cells BL41.

On binding to its receptor, transforming growth factor beta (TGFbeta) induces apoptosis in a variety of cells, including human B lymphocytes. We have previously reported that TGFbeta-mediated apoptosis is caspase-dependent and associated with activation of caspase-3. We show here that caspase-8 inhibitors strongly decrease TGFbeta-mediated apoptosis in BL41 Burkitt's lymphoma cells. These inhibitors act upstream of the mitochondria because they inhibited the loss of mitochondrial membrane potential observed in TGFbeta-treated cells. TGFbeta induced caspase-8 activation in these cells as shown by the cleavage of specific substrates, including Bid, and the appearance of cleaved fragments of caspase-8. Our data show that TGFbeta induces an apoptotic pathway involving sequential caspase-8 activation, loss of mitochondrial membrane potential, and caspase-9 and -3 activation. Caspase-8 activation was Fas-associated death domain protein (FADD)-independent because cells expressing a dominant negative mutant of FADD were still sensitive to TGFbeta-induced caspase-8 activation and apoptosis. This FADD-independent pathway of caspase-8 activation is regulated by p38. Indeed, TGFbeta-induced activation of p38 and two different inhibitors specific for this mitogen-activated protein kinase pathway (SB203580 and PD169316) prevented TGFbeta-mediated caspase-8 activation as well as the loss of mitochondrial membrane potential and apoptosis. Overall, our data show that p38 activation by TGFbeta induced an apoptotic pathway via FADD-independent activation of caspase-8.

Cdk2 associates with MAP kinase in vivo and its nuclear translocation is dependent on MAP kinase activation in IL-2-dependent Kit 225 T lymphocytes.

Cell proliferation is controlled by cdk2 which in association with cyclin E and A regulates G1/S transition and S phase progression. cdk2 activation is dependent on its localization in the nucleus where regulatory mediators are found. We report that activation of cdk2 is associated with the formation of cdk2/MAP Kinase complexes. cdk2 associates with both inactive and activated MAP Kinase. Prevention of MAP Kinase activation by the MEK inhibitor PD98059 inhibits both activation and nuclear localization of cdk2 and S phase entry. These findings indicate that the nuclear translocation of cdk2 is associated with the formation of molecular complexes containing active MAP Kinase and is dependent on MAP Kinase activation. Oncogene (2000) 19, 4184 - 4189