Numerical investigation of mechanisms affecting the piezoresistive properties of CNT-doped polymers using multi-scale models

Carbon nanotube polymer nanocomposites exhibit conductive behavior due to the formation of conductive nanotube networks inside the polymer. Their electrical resistance is known to vary with strain. Two mechanisms that affect the conductivity and piezoresistive response of CNT nanocomposites are investigated using models at two discrete material scales: (a) nanoscale models to analyze the electromechanical response of carbon nanotubes and (b) nanotube percolation models to investigate the composites electrical resistance at microscale. Numerical studies determine the impact of each mechanism on the macroscopic response of the nanocomposite. Results suggest that the variation of nanotube resistance with strain is the dominant mechanism.     

A Stochastic Optimization Approach in the Design of an Aquifer Remediation under Hydrogeologic Uncertainty

A stochastic optimization approach is presented for the remediation design of a contaminated aquifer with limited hydrogeologic information. Stochastic simulation using the Monte Carlo technique, produces a series of equally probable realisations of the spatially varying random hydraulic conductivity field. The stochastic flow and transport simulation model is coupled, using the response matrix approach, with a nonlinear optimization algorithm. The whole process is integrated into an algorithm which is effectively applied in the case study of the Kalamaria aquifer, Chalkidiki, Greece. The stochastic optimization procedure is followed by a reliability analysis, giving useful information to the decision makers concerning the effectiveness of the optimal results.     

Use of FLP/FRT system to study Drosophila development

Mycoplasma fermentans and other Mycoplasma species are colonizers of human mucosal surfaces and may be associated with human immunodeficiency virus infection. While many infectious agents have been described in different percentages of patients with Chronic Fatigue Syndrome (CFS), little is known about the prevalence of mycoplasmas and especially M. fermentans in CFS patients. A polymerase chain reaction (PCR)-based assay was used to detect Mycoplasma genus and M. fermentans genomes in peripheral blood mononuclear cells (PBMC) of CFS patients. Blood was collected from 100 patients with CFS and 50 control subjects. The amplified products of 717 bp of Mycoplasma genus, and 206 bp of M. fermentans were detected in DNA purified from blood samples in 52% and 34% of CFS samples, respectively. In contrast, these genomes were found in only 14% and 8% of healthy control subjects respectively (P < 0.0001). All samples were confirmed by Southern blot with a specific probe based on internal sequences of the expected amplification product. Several samples, which were positive for Mycoplasma genus, were negative for M. fermentans indicating that other Mycoplasma species are involved. A quantitative PCR was developed to determine the number of M. fermentans genome copies present in 1 microg of DNA for controls and CFS patients. Mycoplasma copy numbers ranging from 130 to 880 and from 264 to 2400 were detected in controls and CFS positive subjects, respectively. An enzyme immunoassay was applied for the detection of antibodies against p29 surface lipoprotein of M. fermentans to determine the relationship between M. fermentans genome copy numbers and antibody levels. Individuals with high genome copy numbers exhibited higher IgG and IgM antibodies against M. fermentans specific peptides. Isolation of this organism by culture from clinical specimens is needed in order to demonstrate specificity of signal detected by PCR in this study.