The bacterial adhesion on and the cytotoxicity of various dental cements used for implant-supported fixed restorations.

Objective: Bacterial adhesion on and cytotoxicity of eight luting agents used for implant-supported restorations were investigated.

Materials And Method: Surface roughness (Ra), surface free energy (SFE) values and three-dimensional images by atomic-force microscopy of circular specimens were determined. Bacterial suspensions of Streptococcus sanguinis and Streptococcus epidermidis were incubated at 37°C for 2 h.

Ratchet effects induced by terahertz radiation in heterostructures with a lateral periodic potential.

We report on the observation of the Seebeck ratchet effect. The effect is measured in semiconductor heterostructures with a one-dimensional lateral potential excited by terahertz radiation. The photocurrent generation is based on the combined action of a spatially periodic in-plane potential and a spatially modulated light, which gives rise to a modulation of the local temperature.