Physico-chemical behaviour of irradiated polyimide thin films

The effect of Cu 3+ ion-beam irradiation on the microstructure of two polyimide ( PI ) films ( PMDA-ODA, Kapton ® and BTDA-ODA ) was examined using ATR-FTIR and XPS spectroscopy. The electrical conductivity, Mechanical and Electromechanical properties were also examined. It was found that Cu 3+ ion-beam irradiation was directly responsible for the disruption of the main chain imidic groups in the polymer, which indicated the breakdown of the backbone linkages of the polymer, via cleavage of the nitrogen of the imide and elimination of hydrogen from the PI molecular structure. Electrical conductivity characteristics of the PMDA-ODA films, revealed that they behaved as typical semiconductor films. The resistance of the irradiated films was found to be inversely proportional to temperature, confirming their semiconducting behaviour with calculated thermally sensitive activation barriers in the range 0.4–2.3 eV. The disruption of the main chain imidic groups in the polymer and the formation of the carbon rich channels affected both the tensile strength and the electromechanical properties of the PI films. This is evidenced by changes in Young’s Modulus, and they became slightly brittle at the highest levels of irradiation fluence. The electromechanical properties of PMDA-ODA irradiated films possessed GF values much higher those of conventional composites and an order of magnitude higher than any previously reported. Thus, the irradiated PI films are suitable as sensitive strain gauges with applications as strain sensors, provided they are protected from intense radiation sources

Does fertilization practices increase residual nitrate nitrogen in soil irrigated with treated wastewater? An experimental trial on maize

Treated wastewater has significantly improved DM yield compared to ground water. The form of nitrogen provided by the water was determinant in drawing yields. Irrigation with ground water (where nitrogen is as nitrate) induces a faster migration of nitrogen at depth. In contrast, using treated wastewater (where nitrogen is as ammonium), resulting in a relative distribution of the remaining nitric smaller in the lower profile and therefore higher in the surface, especially after the second year (2010). In addition, the relative distribution of nitrates in the soil surface is even more important in the presence of organic manure. All happens as if a certain amount of ammonium provided by treated wastewater is retained in the organic compounds of manure. Yields were significantly lower in irrigation with treated wastewater in the second year and especially when fertilization was given in additional. If the soil can be used for storage of the nitrogen supplied by the treated wastewater during the first year of irrigation (24 kg N-NO3/ha before irrigation to 115 kg N-NO3/ha after irrigation), to the second year the capacity drops (to 64 N-NO3/ha) and a significant increase in nitrate leaching occurs. Therefore, unlike the contribution of manure that seems enrich the topsoil nitrate nitrogen, at least during the first campaign, mineral fertilization unreasoning causes faster migration of nitrogen at depth

Extracellular matrix components indicate remodelling activity in different fibrosis stages of human non-alcoholic fatty liver disease

AIMS: The composition of several important extracellular matrix components (ECM) has not yet been elucidated in human non-alcoholic fatty liver disease (NAFLD). We aim to investigate the proportion of hepatic stellate cells (HSCs) and activity of matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs) in human NAFLD liver tissue with respect to severity of inflammation and fibrosis. METHODS AND RESULTS: Histopathological features were quantified by NAFLD activity score and grading assignment. The collagen proportionate area (CPA) was measured. Slides were stained with alpha-smooth muscle actin (alpha-SMA), as a marker of activated HSCs, and alpha-SMA was quantified digitally. Zymography was performed to measure the proteolytic activity of MMP-2 and MMP-9. TIMP-1 and TIMP-2 protein concentration was measured with enzyme-linked immunosorbent assay (ELISA). alpha-SMA was higher in severe fibrosis (6.3%, interquartile range 2.9-13.1) than mild and no fibrosis (median 1.1 and 0.9%, P < 0.001) and correlated strongly with CPA (Rs = 0.870, P < 0.001). ProMMP-2 activity in severe (4.1%, IQR 2.6-16.2) and mild fibrosis (2.7%, IQR 1.9-3.9) was higher than in no fibrosis (1.5%, (IQR 0.95-2.1); P = 0.001 and P = 0.046) and showed a moderate positive correlation with CPA (Rs = 0.495, P = 0.001). TIMP-1 and TIMP-2 were significantly higher in severe fibrosis than mild or no fibrosis. Both showed moderate correlation with CPA (TIMP-1: Rs = 0.471, P = 0.002 and TIMP-2: Rs = 0.325, P = 0.036). MMP-9 correlated as the only ECM component to inflammation severity. CONCLUSIONS: Advanced human NAFLD-fibrosis has a distinct ECM composition with increased HSCs and increased TIMP inhibition, but there is also ongoing remodelling activity of MMP-2

Dielectric/metal/dielectric alternative transparent electrode: observations on stability/degradation

The use of indium-free transparent conductive electrodes is of great interest for organic optoelectronic devices. Among the possible replacements for ITO, dielectric/metal/dielectric (D/M/D) multilayer structures have already proven to be quite efficient. One issue with organic devices is their lifetime, which depends not only on the organic molecules used but also on the electrodes. Therefore we study the variation, with elapsed time, of the electrical and optical properties of different D/M/D structures, with M  =  Ag or Cu/Ag. Six years after realization, it has been shown that if some structures retained an acceptable conductivity, some others became non-conductive. For a sample which remains conductive, in the case of a PET/MoO3/Ag/MoO3 multilayer structure, the sheet resistance changes from 5 Ω/sq–17 Ω/sq after six years. This evolution can be compared to that of a PET/ITO electrode that varies from 25 Ω/sq–900 Ω/sq after six years. It means that not only are the PET/MoO3/Ag/MoO3 multilayer structures more flexible than PET/ITO, but they can also be more stable. Nevertheless, if some PET/MoO3/Ag/MoO3 multilayer structures are quite stable, some others are not. This possible degradation appears to be caused primarily by the physical agglomeration of Ag, which can result in Ag film disruption. This Ag diffusion seems to be caused by humidity-induced degradation in these Ag-based D/M/D structures. Initially, defects begin to grow at a \u27nucleus\u27, usually a microscopic particle (or pinhole, etc), and then they spread radially outward to form a nearly circular pattern. For a critical density of such defects, the structure becomes non-conductive. Moreover the effect of humidity promotes Ag electrochemical reactions that produce Ag+ ions and enhances surface diffusivity with AgCl formation

Efficient hole-transporting layer MoO3:CuI deposited by co-evaporation in organic photovoltaic cells

In order to improve hole collection at the interface anode/electron donor in organic photovoltaic cells, it is necessary to insert a hole transporting layer. CuI was shown to be a very efficient hole transporting layer. However, its tendency to be quite rough tends to induce leakage currents and it is necessary to use a very slow deposition rate for CuI to avoid such negative effect. Herein, we show that the co-deposition of MoO3 and CuI avoids this difficulty and allows deposition of a homogeneous efficient hole-collecting layer at an acceptable deposition rate. Via an XPS study, we show that blending MoO3:CuI improves the hole collection efficiency through an increase of the gap state density. This increase is due to the formation of Mo5þ following interaction between MoO3 and CuI. Not only does the co-evaporation process allow for decreasing significantly the deposition time of the hole transporting layer, but also it increases the efficiency of the device based on the planar heterojunction, CuPc/C60

Microstructural properties of ZnO :Sn thin films deposited by intermittent spry pyrolysis process

Zinc oxide films have been prepared via spray pyrolysis using a perfume atomizer. ZnCl2 has been used as precursor. The influence of the precursor solution and dopant concentration has been investigated. Homogeneous films are obtained with a precursor concentration ranging between 0.3 and 0.4 M and a SnCl2 dopant concentration of 1–2%. The films exhibit broad band gaps and small conductivity. The microstructural properties of these films have been compared with that of films deposited using a classical nozzle. Films deposited by perfume atomizer are rougher, with smaller grain size, compared to films deposited with a classical nozzle

Social Climber attachment in forming networks produces phase transition in a measure of connectivity

Formation and fragmentation of networks is typically studied using percolation theory, but most previous research has been restricted to studying a phase transition in cluster size, examining the emergence of a giant component. This approach does not study the effects of evolving network structure on dynamics that occur at the nodes, such as the synchronization of oscillators and the spread of information, epidemics, and neuronal excitations. We introduce and analyze new link-formation rules, called Social Climber (SC) attachment, that may be combined with arbitrary percolation models to produce a previously unstudied phase transition using the largest eigenvalue of the network adjacency matrix as the order parameter. This eigenvalue is significant in the analyses of many network-coupled dynamical systems in which it measures the quality of global coupling and is hence a natural measure of connectivity. We highlight the important self-organized properties of SC attachment and discuss implications for controlling dynamics on networks.Comment: 6 pages, 4 figure

Broadening of the transmission range of dielectric/metal multilayer structures by using different metals

ZnS/M12/ZnS structures, with M12 ¼ Ag, Cu or Cu/Ag, were deposited under vacuum by simple joule heating effect (sublimation or evaporation). The optimum thicknesses of the different layers were experimentally determined: 50/45 nm for ZnS, 11 nm for Ag, 16 nm for Cu and 3 nm/9 nm for Cu/Ag. The presence of the double metal Cu/Ag interlayer induces a significant broadening of the optical transmittance spectrum of these structures. The properties of the structures depend strongly on deposition rate of the different films. When the deposition rates of ZnS, Cu are 0.15 nm/s and 0.30 nm/s for Ag, the averaged transmission, between 400 nm and 1000 nm is 85% while the sheet resistance is 5.0 ± 0.2 Ω/sq. These performances allow achieving an averaged factor of merit ΦM, between 400 nm and 700 nm, of 70 x 10-3 Ω-1. This averaged value tends toward those usually achieved by transparent conductive oxides

Hurler disease (mucopolysaccharidosis type IH): clinical features and consanguinity in Tunisian population

Mucopolysaccharidosis type I (MPS I) was a group of rare autosomal recessive disorder caused by the deficiency of the lysosomal enzyme, alpha -L -iduronidase, and the resulting accumulation of undergraded dematan sulfate and heparan sulfate. MPS I patients have a wide range of clinical presentations, that makes it difficult to predict patient phenotype which is needed for genetic counseling and also impedes the selection and evaluation of patients undergoing therapy bone marrow transplantation