Mikrobielle Zerstörung keramischer Werkstoffe

Microbial destruction of ceramic materials Ceramic materials-natural stones, concrete, ceramics, and glass-are subjected to attack by microorganisms. This biodeterioration may contribute substantially to the decay of materials. Generally the biological testing of the resistance of ceramic materials to biogenic attack can not be substituted by chemical and/or physical testing. The biotest includes the evaluation of the interactions between microorganisms and environment, especially the substratum (ceramic material). In case of the biogenic sulfuric or nitric acid corrosion the biotest of the materials in a strictly controlled simulation apparatus resulted in differences of the materials durability, which could not be detected by other testing methods. Chemical sulfuric acid attack resulted in negligible differences. Thus the use of biotest systems enables us to detect within many different materials the appropiate ones.     

Effect of NCAM-transfection on growth and invasion of a human cancer cell line

A cDNA encoding the human transmembrane 140 kDa isoform of the neural cell adhesion molecule (NCAM) was transfected into the highly invasive MDA-MB-231 human breast cancer cell line. Transfectants with a homogeneous expression of NCAM showed a restricted capacity for penetration of an artificial basement membrane. However, when injected into nude mice, both control and NCAM-expressing cell lines produced equally invasive tumors. Tumors generated from NCAM-transfected cells were heterogeneous, containing NCAM-positive as well as NCAM-negative areas, indicating the existence of host factors capable of modulating NCAM expression in vivo. In nude mice, NCAM-transfected cells developed tumors with longer latency periods and slower growth rates than tumors induced by NCAM-negative control cells, implying that NCAM may be involved not only in adhesive and motile behavior of tumor cells but also in their growth regulation. There was no indication of differences in cell proliferative characteristics between the different NCAM-transfected and the control transfected cells as determined by flow cytometric DNA analysis, suggesting an increased cell loss as the reason for decreased in vivo growth rate of the NCAM-transfected cells. The fact that NCAM expression influences growth regulation attributes a pivotal role to this cell adhesion molecule during ontogenesis and tumor development.     

Simulation study for the CDM ESD behaviour of the grounded-gate nmos

The parasitic bipolar transistor inherent to grounded gate nMOSts is modelled accounting for the specific conditions applied by CDM ESD stress. The impact of the gate length on the CDM-specific bipolar saturation mode is addressed. The different operation modes occurring during CDM ESD stress translate to self-heating which explains the observed test results.     

Perceptual grouping in visual word recognition

Morphine has been reported to possess immunosuppressive actions in both in vitro as well as in vivo assays of immune function. Our work in female B6C3F1 mice, surgically implanted with a 75-mg time release morphine pellet, has confirmed previous reports of a rapid loss in the cellularity of the spleen and thymus. To evaluate the effect of morphine on the subpopulations of cells in the thymus, two color fluorescence flow cytometry studies were performed. Fluorescently conjugated monoclonal antibodies specific for the murine cell surface CD4 and CD8 markers were used to identify the four major subpopulations of thymocytes. These studies indicated that morphine pellet-implanted mice suffered a loss in each of the four thymocyte subpopulations in comparison to placebo-implanted mice. However, the loss (> 90%) in the important CD4+/CD8+ subpopulation of immature thymocytes greatly exceeded that which was observed for any other subpopulation. Kinetic studies of morphine's effect on the thymocyte subpopulations revealed that the maximal depletion of the CD4+/CD8+ cells occurs approximately 4 days after pellet implantation. Thymocyte cell populations recovered by 14 days, with an increase above placebo for the double positive cells. Naltrexone administration blocked thymic alterations, suggesting that these immunologic consequences of morphine may be mediated through an opiate receptor. Measurements in thymocytes from morphine pellet-implanted mice showed an increased level of DNA fragmentation, whereas in vitro exposure to morphine (1-100 microM) produced no such increases. This suggests morphine may be working indirectly to induce apoptosis of immature thymocytes.