Parameter Screening Study for Optimizing the Static Properties of Nanoparticle-Stabilized CO2 Foam Based on Orthogonal Experimental Design.

Nanoparticle (NP)-stabilized foam technology has found potential applications in CO2 enhanced oil recovery (EOR) and greenhouse gas geological storage practices and accordingly attracts lots of research interest. To screen the optimal formula for the satisfactory foam performance, orthogonal experimental design (OED) is used in this paper for the complex multifactor multilevel system consisting of five influential factors of NP size, surfactant concentration, NP concentration, temperature, and salinity at four different levels in the range of 7-40 nm, 0-0.15 wt %, 0-0.2 wt %, 25-55 °C, and 0-3 wt %, respectively. Based on the orthogonal principle, only 16 experiments were performed to analyze the effect of various factors on the foam height and foam half-life properties. In addition to showing that the influence of the single factor on foam static properties, OED results reveal that the surfactant concentration and temperature are dominating factors on foamability and stability of the NP-stabilized CO2 foam, respectively. Finally, NP-stabilized CO2 foam with satisfactory static characteristics is obtained with the OED recommended composition of a 0.15 wt % surfactant concentration, 0.1 wt % NP concentration, and NP size of 7 nm in 1 wt % saline solution at temperatures of 30 and 50 °C, validating that the OED method could substantially facilitate the laboratory screening and optimization process for a successful NP-stabilized CO2 foam application.

Suppression of cell migration by protein kinase Cdelta.

The ability of cancer cells to migrate is strongly correlated with malignant progression and metastasis. Survival signals that suppress apoptosis have also been linked to increased cell motility. We previously reported that suppression of protein kinase Cdelta (PKCdelta) provided survival signals in a rat fibroblast model system. These studies have been extended to human breast cancer cells with differential cell motilities and PKCdelta levels. BT-549 cells, which lack detectable expression of PKCdelta, migrate very efficiently, whereas MCF-7 cells, which express high levels of PKCdelta, migrate very poorly. Ectopic expression of PKCdelta suppressed cell migration in the BT-549 cells, and downregulation of PKCdelta enhanced cell migration in the MCF-7 cells. Downregulation of PKCdelta in the MCF-7 cells also led to increased secretion of the matrix metalloprotease MMP-9. The migration of mouse embryo fibroblasts (MEFs) from wild type and PKCdelta knockout mice was also examined and MEFs from PKCdelta knockout mice had a five-fold increase in cell migration relative to the wild-type MEFs. These data provide evidence that PKCdelta suppresses cell migration in both human breast cancer cells and in primary mouse fibroblasts, and indicate that the loss of PKCdelta in human cancers could contribute to both cell survival and metastasis.