Human Omental Mesothelial Cells Impart an Immunomodulatory Landscape Impeding B- and T-Cell Activation

Mesothelial cells form the mesothelium, a simple epithelium lining the walls of serous cavities and the surface of visceral organs. Although mesothelial cells are phenotypically well characterized, their immunoregulatory properties remain largely unknown, with only two studies reporting their capacity to inhibit T cells through TGF-β and their consumption of L-arginine by arginase-1. Whether human mesothelial cells can suppress other immune cells and possess additional leukosuppressive mechanisms, remain to be addressed to better delineate their therapeutic potential for cell therapy. Herein, we generated secretomes from omental mesothelial cells (OMC) and assess their capacity to inhibit lymphocytes proliferation, suppress activated T and B cells, as well as to modify macrophage activation markers. The secretome from mesenchymal stromal cells (MSC) served as a control of immuno-suppression. Although OMC and MSC were phenotypically divergent, their cytokine secretion patterns as well as expression of inflammatory and immunomodulary genes were similar. As such, OMC- and MSC-derived secretomes (OMC-S and MSC-S) both polarized RAW 264.7 macrophages towards a M2-like anti-inflammatory phenotype and suppressed mouse and human lymphocytes proliferation. OMC-S displayed a strong ability to suppress mouse- and human-activated CD19⁺/CD25⁺ B cells as compared to MSC-S. The lymphosuppressive activity of the OMC-S could be significantly counteracted either by SB-431542, an inhibitor of TGFβ and activin signaling pathways, or with a monoclonal antibody against the TGFβ1, β2, and β3 isoforms. A strong blockade of the OMC-S-mediated lymphosuppressive activity was achieved using L-NMMA, a specific inhibitor of nitric oxide synthase (NOS). Taken together, our results suggest that OMC are potent immunomodulators.     

Prediction of creep–fatigue crack growth rates in inert and active environments in an aluminium alloy

This paper reports on a study on creep–fatigue crack growth resistance of a precipitation hardened 2650 T6 aluminium alloy selected for fuselage panels of a future civil supersonic aircraft. The objective is to develop a methodology to predict crack growth under very low frequency loading at elevated temperatures. With this aim, creep crack growth rates (CCGRs), fatigue crack growth rates (FCGRs), creep–fatigue crack growth rates (CFCGRs) have been measured at 130 °C and 175 °C in laboratory air and in vacuum at R = 0.5 under different load frequencies and waveshape signals. It is shown that, for a given temperature, CFCGRs are unaffected by frequency below a critical value of the load period T_c. Above this value CFCGRs are directly proportional to the load period. This time-dependent crack growth regime is assisted by a significant creep damage as indicated by the large amount of intergranular decohesions induced by cavitation on fracture surfaces. CFCGRs are calculated under the assumption that fatigue damage and creep damage can be linearly summed. In vacuum the predictions are in good agreement with experimental data at both temperatures. In air however a discrepancy is observed for low frequency loading, suggesting the occurrence of a creep–fatigue–environment interaction. As a consequence the time-dependent crack growth behaviour affected by this interaction is different from creep crack growth behaviour, although the reasons for this are still unclear. A methodology is then proposed to predict CFCGRs in air. This methodology, if assessed by very low frequency experimental results, could be extended to different structural components made of aluminium alloys operating at elevated temperatures, provided that the mechanisms are unchanged.     

Synthesis of single-walled carbon nanotubes by induction thermal plasma

The production of high quality single-walled carbon nanotubes (SWCNTs) on a bulk scale has been an issue of considerable interest. Recently, it has been demonstrated that high quality SWCNTs can be continuously synthesized on large scale by using induction thermal plasma technology. In this process, the high energy density of the thermal plasma is employed to generate dense vapor-phase precursors for the synthesis of SWCNTs. With the current reactor system, a carbon soot product which contains approximately 40 wt% of SWCNTs can be continuously synthesized at the high production rate of ∼100 g/h. In this article, our recent research efforts to achieve major advances in this technology are presented. Firstly, the processing parameters involved are examined systematically in order to evaluate their individual influences on the SWCNT synthesis. Based on these results, the appropriate operating conditions of the induction thermal plasma process for an effective synthesis of SWCNTs are discussed. A characterization study has also been performed on the SWCNTs produced under the optimum processing conditions. Finally, a mathematical model of the process currently under development is described. The model will help us to better understand the synthesis of SWCNTs in the induction plasma process.      

Effect of environmental conditions on expansion in concrete due to alkali–silica reaction (ASR)

The environmental conditions to which a concrete element incorporating alkali–silica reactive aggregates is exposed play a major role in dictating the progression and manifestation of the reaction. This paper reports and analyses the results of research programs investigating the comparative evaluation of the effect of environmental conditions on the development of alkali–silica reaction (ASR) in concrete specimens stored in outdoor exposure at the authors' respective laboratories. This data is compared to samples subjected to laboratory testing (controlled environmental conditions). Concrete mixtures that incorporate reactive aggregates with varying reactivity levels are compared. The focus of this paper is on control concretes e.g. 100% opc + reactive aggregate (coarse or fine).     

Large signal design method of distributed power amplifiers applied to a 2–18-GHz GaAs chip exhibiting high power density performances

A suitable large signal design method of distributed power amplifiers, based on the optimum FET load requirement for high power operation, is proposed in this article. The gate and drain line characteristic admittances are determined, providing both the initial values and right directions for an optimum design. To validate the proposed design method, a FET amplifier demonstrator with a gate periphery of 1.2 mm has been manufactured at the Texas Instruments foundry. The MMIC distributed amplifier demonstrated an improved power density performance of 340 mW/mm over the 2–18-GHz frequency band associated with a minimum of 13% power-added efficiency and 24% drain efficiency at 1-dB compression in CW operation. © 1996 John Wiley & Sons, Inc.     

Decolorization, cytotoxicity, and genotoxicity reduction during a combined ozonation/fungal treatment of dye-contaminated wastewater

In view of compliance with increasingly stringent environmental legislation imposed by regional, national, and supranational (e.g., European Union) authorities, innovative environmental technologies for the treatment of dye-contaminated effluents are necessary in the color industry. In this study, effluents of an industrial dye producer were subjected to distinct treatment trains following an initial qualitative characterization. The effectiveness of ozonation and a treatment using white rot fungi (WRF) and their enzymes were compared with respect to parameters such as residual color, toxicity on human cells, and genotoxicity. A combined ozonation/WRF process was also investigated. The effluent exhibited significant toxicity that was reduced by only 10% through ozonation, whereas the fungal treatment achieved a 35% reduction. A combined treatment (ozone/WRF) caused an abatement of the toxicity by more than 70%. In addition, the initial genotoxicity of the effluent was still present after the ozone treatment, while it was completely removed through the fungal treatment.     

Novel method to produce single-walled carbon nanotube films and their thermal and electrical properties

Single-walled carbon nanotube films are promising candidates for applications requiring transparent conductors due to their low sheet resistance and high transparency in the visible region. Vacuum filtration is a common and easy to implement technique to produce such films but it is complicated by the need to transfer the films to desired substrates. Here we report conditions under which single-walled carbon nanotube films produced by vacuum filtration detach from the filter membrane upon submersion into water, providing a facile method to transfer filtration-produced nanotube films to desired substrates. Sheet resistance and transparency measurements show that these films are competitive with other high conductivity films made through more cumbersome procedures. Films post-treated with nitric acid or made with acid pre-treated nanotubes have superior performance to those made with high-purity nanotubes without any acid treatment. Thermal imaging by scanning thermal microscopy indicates that heat dissipation by the film is comparable to that of a glass substrate.