Nonexponetial relaxation of photoinduced conductance in organic field effect transistor

We report detailed studies of the slow relaxation of the photoinduced excess charge carriers in organic metal-insulator-semiconductor field effect transistors consisting of poly(3-hexylthiophene) as the active layer. The relaxation process cannot be physically explained by processes, which lead to a simple or a stretched-exponential decay behavior. Models based on serial relaxation dynamics due to a hierarchy of systems with increasing spatial separation of the photo-generated negative and positive charges are used to explain the results. In order to explain the observed trend, the model is further modified by introducing a gate voltage dependent coulombic distribution manifested by the trapped negative charge carriers.Comment: 17 pages, 3 Figure

Sistemas Agroflorestais como Estratégia de Adaptação aos Desafios das Mudanças Climáticas no Brasil

This paper analyzes the role of agroforestry systems (AFS) as an adaptative measure to climate change in Brazil. A treatment-effects model (Propensity Score Matching) was developed. We identified the main determinants of the use of AFS and if the municipalities in which this technique is used are less vulnerable to climate change. The results showed that socioeconomic variables (land ownership, financing options, access to information and technical assistance) and agronomic variables (water resources availability and soil quality) influence the adoption of agroforestry systems in Brazilian municipalities. Climate conditions (temperature and precipitation) also play an important role in the use of these systems, which confirms their role as an adaptative strategy. It was also concluded that the AFS have the potential to improve the Brazilian agricultural performance due to the fact that the land value tends to be higher in municipalities where these systems are used. Thus, the AFS can make the agricultural sector less exposed to the negative effects of climate change in both the present and in future scenarios

Anthracene-tethered ruthenium(II) arene complexes as tools to visualize the cellular localization of putative organometallic anticancer compounds.

Anthracene derivatives of ruthenium(II) arene compounds with 1,3,5-triaza-7-phosphatricyclo[3.3.1.1]decane (pta) or a sugar phosphite ligand, viz., 3,5,6-bicyclophosphite-1,2-O-isopropylidene-α-d-glucofuranoside, were prepared in order to evaluate their anticancer properties compared to the parent compounds and to use them as models for intracellular visualization by fluorescence microscopy. Similar IC(50) values were obtained in cell proliferation assays, and similar levels of uptake and accumulation were also established. The X-ray structure of [{Ru(η(6)-C(6)H(5)CH(2)NHCO-anthracene)Cl(2)(pta)] is also reported