Calcium ions react with silicic acid released from dissolving porous silicon nanoparticles to create an insoluble calcium silicate shell. The calcium silicate shell traps and protects an siRNA payload, which can be delivered to neuronal tissues in vitro or in vivo. Gene delivery is enhanced by the action of targeting and cell-penetrating peptides attached to the calcium silicate shell.

In spite of the intense efforts of metrics researches, the impact of object-oriented software metrics is for the moment still quite reduced. The cause of this fact lies not in an intrinsic incapacity of metrics to help assessing and improving the quality of object-oriented systems, but in an unsystematic, dispersed and ambiguous manner of defining and using the metrics. In this paper we define ...

This paper presents the EarthTutor authoring tool, a multi-layered system designed to remove the technical hurdles preventing teachers from having full control over the structure of their lessons, without sacrificing the power and technical flexibility required for an effective ITS implementation. EarthTutor reduces the ITS design problem to a series of related but independent layers. Each laye...

Application of silicate solutions to living or heat-killed pneumococci and to certain "viridans" streptococci causes their conversion from a Gram-positive to a Gram-negative state. The original staining properties can be restored by suspending the silicate-treated bacteria in alkaline solutions of various salts but not by simple washing in water. Living pneumococci and the strains of streptococ...