This study was aimed at investigating the in vitro biocompatibility of a novel membrane of the composite poly(vinylidene-trifluoroethylene)/barium titanate (P(VDF-TrFE)/BT). Osteoblastic cells were obtained from human alveolar bone fragments and cultured under standard osteogenic condition until subconfluence. First passaged cells were cultured on P(VDF-TrFE)/BT and expanded polytetrafluoroethylene (e-PTFE--control) membranes in 24-well plates. Cell adhesion and spreading were evaluated at 30 min, and 4 and 24 h. For proliferation assay, cells were cultured for 1, 7, and 10 days. Cell viability was detected by trypan blue at 7 and 10 days. Total protein content and alkaline phosphatase (ALP) activity were measured at 7, 14, and 21 days. Cultures were stained with Alizarin red at 21 days, for detection of mineralized matrix. Data were compared by ANOVA and Student t test. Cell attachment (p = 0.001), cell number (p = 0.001), and ALP activity (p = 0.0001) were greater on P(VDF-TrFE)/BT. Additionally, doubling time was greater on P(VDF-TrFE)/BT (p = 0.03), indicating a decreased proliferation rate. Bone-like nodule formation took place only on P(VDF-TrFE)/BT. The present results showed that both membranes are biocompatible. However, P(VDF-TrFE)/BT presented a better in vitro biocompatibility and allowed bone-like nodule formation. Therefore, P(VDF-TrFE)/BT could be an alternative membrane to be used in guided tissue regeneration.

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Currently, numerous properties of semiconducting oxides are correlated to their morphological characteristics resulting from their exposed surfaces. In the present work, the relationship between the following morphologies rod, bean, hexagon, and rod/cube of CeO2 with the exposure of (111), (110), (100), and (311) surfaces and the main charge carriers generated by the photochemical processes was investigated. This was done in regard to the degradation of ciprofloxacin and rhodamine-B. The initial stages of the degradation of the two types of molecules were evaluated, allowing the determination of where the charge carriers generated in the semiconductor preferentially acted on the molecules. Therefore, the active species in each photocatalyst were identified by scavenger tests and correlated to the computational simulations using the density functional theory. Accordingly, the relationships between the morphology, surface exposure in the particles, surface defects, photochemically generated species, and preferential attack on the micropollutant molecule were shown. Specific surface area analyses demonstrate an effective relationship between photocatalytic activity and the exposed surface of the particle. This will allow rationalization of the relation between the catalytic and electronic properties of semiconductor surfaces.

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a b s t r a c tPerovskite solar cells have attracted attention due its high conversion efficiency and low cost. In this work, Nb 2 O 5 is used as an alternative compact hole blocking layer in conjunction with mesoporous TiO 2 and CH 3 NH 3 PbI 3 in perovskite solar cells. The influence of Nb 2 O 5 layer thickness was studied and it was found to strongly influence the J-V hysteresis of the cells. Devices constructed with 50 nm Nb 2 O 5 have small or undetectable hysteresis, which becomes detectable and increases with increasing Nb 2 O 5 layer thickness. For the best device, energy conversion efficiency of up to 12%, short-circuit currents of 17 mA/cm 2 and fill factors of 74% were found. These parameters are comparable to the best performance of similar devices where the compact layer is TiO 2 . In addition, the use of Nb 2 O 5 improved the stability of the solar cells under illumination. These improvements are attributed to a better extraction of photogenerated electrons in the perovskite layer.

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