Evaluation of alternative sludge settleability indices

Proposed modifications of the standard sludge volume index (SVI) to eliminate its unpredictable variation with suspended solids (SS) concentration include stirring, conduct of the test at constant SS concentration, and dilution. We have tested these modifications by making correlations between the respective indices and the content of filamentous organisms in activated sludge expressed in terms of total extended filament length. The results indicate that diluted SVI is the best index of sludge settleability among those tested. Correlation of diluted SVI with specific functional relationships between settling velocity and SS concentration would enable the application of this parameter to prediction of thickening capacity in secondary clarifiers.     

Circuit modeling of the emitter-wrap-through solar cell

Back-contact solar cells have the potential to reduce module assembly costs and give a higher conversion efficiency. Such a device must be simple to fabricate on an industrial scale and be tolerant of low minority-carrier diffusion lengths. The emitter-wrap-through (EWT) cell is a device design that can meet these goals. In this device, the diffused junction is present on both sides and is connected by laser-drilled holes through the silicon. EWT cells were frequently found to have poor fill factors (FFs) due to shunt-like behavior. The holes were found to possess no defects that adversely affect device performance. However, detailed equivalent circuit modeling of the EWT cell was able to explain the shunt-like behavior. Experiments were performed to confirm the physical mechanisms described by the equivalent circuit model. Device optimization guided by the equivalent circuit model has led to the demonstration of a large area EWT cell with a FF of 77.64% and efficiency of 18.2%     

A vector based on the SV40 origin of replication and chromosomal S/MARs replicates episomally in CHO cells

We have developed an episomal replicating expression vector in which the SV40 gene coding for the large T-antigen was replaced by chromosomal scaffold/matrix attached regions. Southern analysis as well as vector rescue experiments in CHO cells and in Escherichia coli demonstrate that the vector replicates episomally in CHO cells. It occurs in a very low copy number in the cells and is stably maintained over more than 100 generations without selection pressure.     

Prothymosin alpha 1 effects in vitro on chemotaxis, cytotoxicity and oxidative response of neutrophils from melanoma, colorectal and breast tumor patients

Immunoregulatory effects of thymic peptides on functions of polymorphonuclear leukocytes (PMNs) are poorly investigated. We studied the effects of prothymosin alpha 1 (Pro alpha 1) on PMNs from patients with colorectal tumors, breast tumors and melanoma (total n = 37) in comparison with healthy donors (n = 18), with respect to chemotaxis, cytotoxicity against HCT-116 colon tumor cells, oxidative response (chemiluminescence reaction) as well as expression of surface marker molecules. We found that Pro alpha 1 was equally effective in stimulating the chemotactic activity of PMNs from tumor patients and healthy donors (43% increase). PMNs from tumor patients, especially with breast tumor, showed a significant enhancement of cytotoxicity against the tumor target cells in comparison with healthy donors. With respect to the PMNs cytotoxicity, only about 50% of the colorectal tumor patients and healthy donors responded to Pro alpha 1 and FMLP. As to the oxidative response of PMNs, elevated levels were found only among colorectal tumor patients. Pro alpha 1 significantly increased the oxidative response in breast and colorectal tumor patients by 55% and 25%, respectively. Pro alpha 1 decreased the expression of CD16 on PMNs of healthy donors, but not that of CD11a, CD11b, CD11c, CD13, CD14, CD15 and CD32. Therefore, we suggest, that Pro alpha 1 may improve some PMN functions of tumor patients, associated with the proposed role in host-tumor interaction.