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Metal-insulator-semiconductor capacitors are investigated, in which the insulator is cross-linked polyvinylphenol and the active layer a blend of poly(3-hexylthiophene), P3HT, and the electron acceptor [6,6] -phenyl-C61 -butyric acid methyl ester (PCBM). Admittance spectra and capacitance-voltage measurements obtained in the dark both display similar behaviour to those previously observed in P3HT-only devices. However, the photo-capacitance response is significantly enhanced in the P3HT:PCBM case, where exciton dissociation leads to electron transfer into the PCBM component. The results are consistent with a network of PCBM aggregates that is continuous through the film but with no lateral interconnection between the aggregates at or near the blend/insulator interface. [ABSTRACT FROM AUTHOR]

SummaryAims The rheological properties of erythrocytes are impaired in diabetes mellitus, especially because of changes in their membrane lipid composition. In hypercholesterolaemic patients, lowering plasma cholesterol is associated with an improvement of the erythrocyte rheological parameters. The aim of this study was to investigate the relationship between erythrocyte deformability, plasma lipids, lipid membrane composition and cytosolic cations in poorly controlled Type 2 diabetic patients and to test the effects of a cholesterol-lowering treatment on these parameters. Methods We compared 37 poorly controlled Type 2 diabetic patients with 26 controls. In 22 of the diabetic patients who showed an impairment in erythrocyte deformability (filtration index > 10.5 on the Hanss’ haemorheometer), a double-blind randomized trial compared the effect of the inhibitor of HMG CoA reductase pravastatin 20 mg per day for 4 months vs. placebo on the erythrocyte parameters. Results Compared with controls, diabetic patients had higher filtration index (FI), erythrocyte sodium and calcium contents and lower free cholesterol–phospholipids ratio in erythrocyte membranes. Erythrocyte sodium content correlated positively with the FI and the membrane free cholesterol–phospholipids ratio. In the pravastatin-treated group (11 patients), fibrinogen decreased significantly, FI reached a normal value (< 10) in six patients. Four of the five other patients who still had abnormal FI after 4 months of treatment had either a high plasma triglycerides (≥ 4.60 mmol/l) or a high plasma fibrinogen (≥ 4 g/l) level at baseline. Only two of the 11 placebo-treated patients achieved a normal FI. Conclusion These data suggest that in poorly controlled Type 2 diabetic patients there is a link between the chemical composition and the rheological properties of erythrocytes. Erythrocyte deformability may be improved by lowering plasma cholesterol with a statin. [ABSTRACT FROM AUTHOR]

The detection of nitric oxide (NO) release by human polymorphonuclear neutrophil leukocytes (PMNs) presents several difficulties, mainly due to concomitant production of O2- and H2O2, which could interfere with the measurements. A Nafion and nickel porphyrin-coated microelectrode was used to measure NO production in PMNs in vitro. It allowed detection of 6.3±1.9 nM NO in a PMN-containing system and was unaffected by added chemicals. Addition of the chemotactic oligopeptide f-met-leu-phe (fMLP; 100 nM) induced a NO release which reached a value of 71±30 pmol NO/106 PMN×ml[sup -1] 5 min after stimulation in the presence of SOD (150 U/ml). If SOD was omitted, the corresponding value was 36±20 pmol NO/106 PMN×ml-1. Presence or absence of catalase did not alter the amount of NO measured. Addition of the NO-synthase inhibitor NG-monomethyl-L-arginine (LNMMA; 1 mM) reduced the current by 82 ± 20%. These results agree with the rate of NO production in human PMNs when measured spectrophotometrically using the NO-dependent oxidation of oxyhaemoglobin to methaemoglobin. The NO production in human PMN was dependent on fMLP concentrations, but independent of cell-concentrations of 0.5-3.5×106/ml. This paper shows that a electrochemical method, e.g. Nafion and porphyrin-coated microelectrode, is suitable for studies of NO release from stimulated human PMNs. [ABSTRACT FROM AUTHOR]

The effect of OTS (octadecyltrichlorosilane) Self-Assembled Monolayer (SAM) grafted on SiO2 gate dielectric of pentacene-based OFETs (organic field-effect transistors) is investigated. A significant improvement of the charge mobility (μ), up to 0.74 cm2/V s, is reached thanks to OTS treatment. However, in spite of improved performances, several drawbacks, such as an increase in mobility dispersion, substantial hysteresis in IDS-VG characteristics and high threshold voltages (VT), are observed. Changing solvent and deposition method turns out to have no significant effect on the mobility dispersion. A more accurate approach on the evolution of the mobility and the threshold voltage dispersion with OTS storage time highlights the effect of the OTS solution aging. Even if no difference is evidenced in the surface energy and roughness of the OTS layer, electrical characteristics exhibit considerable deterioration with OTS solution storage time. Using an “aged” OTS solution, opened under air, kept under argon and distilled before use, results in an increase of the IDS-VG hysteresis as well as in VT and in mobility dispersion. In comparison, fresh-OTS-based OFETs present a very low hysteresis, a threshold voltage close to 0 and a much lower mobility dispersion. It is demonstrated that aged OTS solutions contain impurities that are not removed by distillation process, which leads to a less densely packed layer causing interfacial charge traps thus deteriorated performances. [ABSTRACT FROM PUBLISHER]