Analysis of deep levels in a phenylenevinylene polymer by transient capacitance methods

Transient capacitance methods were applied to the depletion region of an abrupt asymmetric n(+) -p junction of silicon and unintentionally doped poly[2-methoxy, 5 ethyl (2' hexyloxy) paraphenylenevinylene] (MEH-PPV). Studies in the temperature range 100-300 K show the presence of a majority-carrier trap at 1.0 eV and two minority traps at 0.7 and 1.3 eV, respectively. There is an indication for more levels for which the activation energy could not be determined. Furthermore, admittance data reveal a bulk activation energy for conduction of 0.12 eV, suggesting the presence of an additional shallow acceptor state. (C) 1999 American Institute of Physics. [S0003-6951(99)02308-6].

Determination of deep and shallow levels in conjugated polymers by electrical methods

Conjugated organic semiconductors have been submitted to various electrical measurement techniques in order to reveal information about shallow levels and deep traps in the forbidden gap. The materials consisted of poly[2-methoxy, 5 ethyl (2' hexyloxy) paraphenylenevinylene] (MEH-PPV), poly(3-methylthiophene) (PMeT), and alpha-sexithienyl (alpha T6) and the employed techniques were IV, CV, admittance spectroscopy, TSC, capacitance and current transients. (C) 1999 Elsevier Science B.V. All rights reserved.

Electronic levels in MEH-PPV

pn-Junctions of MEH-PPV on top of heavily doped n-type silicon were used in electrical measurements. Through deep-level transient-spectroscopy (DLTS)-like measurements, four traps (two majority and two minority traps) could be identified on top of the shallow acceptor level responsible for conduction. Furthermore, evidence is found for interface states. (C) 2000 Published by Elsevier Science S.A. All rights reserved.

Development of an ecotoxicological protocol for the deep-sea fauna using the hydrothermal vent shrimp Rimicaris exoculata

In light of deep-sea mining industry development, particularly interested in massive-sulphide deposits enriched in metals with high commercial value, efforts are increasing to better understand potential environmental impacts to local fauna. The aim of this study was to assess the natural background levels of biomarkers in the hydrothermal vent shrimp Rimicaris exoculata and their responses to copper exposure at in situ pressure (30MPa) as well as the effects of depressurization and pressurization of the high-pressure aquarium IPOCAMP. R. exoculata were collected from the chimney walls of the hydrothermal vent site TAG (Mid Atlantic Ridge) at 3630m depth during the BICOSE cruise in 2014. Tissue metal accumulation was quantified in different tissues (gills, hepatopancreas and muscle) and a battery of biomarkers was measured: metal exposure (metallothioneins), oxidative stress (catalase, superoxide dismutase, glutathione-S-transferase and glutathione peroxidase) and oxidative damage (lipid peroxidation). Data show a higher concentration of Cu in the hepatopancreas and a slight increase in the gills after incubations (for both exposed groups). Significant induction of metallothioneins was observed in the gills of shrimps exposed to 4μM of Cu compared to the control group. Moreover, activities of enzymes were detected for the in situ group, showing a background protection against metal toxicity. Results suggest that the proposed method, including a physiologically critical step of pressurizing and depressurizing the test chamber to enable the seawater exchange during exposure to contaminants, is not affecting metal accumulation and biomarkers response and may prove a useful method to assess toxicity of contaminants in deep-sea species.