An Operational Supramolecular Nanovalve

An operational supramolecular nanovalve.

A functioning nanomachine in the form of a supramolecular nanovalve that opens and closes the orifices to molecular-sized pores and releases a small number of molecules on demand is reported. The nanovalve, which is used to open and close the nanocontainer, is a pseudorotaxane composed of two components-a long thread containing a 1,5-dioxnaphthalene donor unit, which is attached to the solid su...

Construction of a pH-driven supramolecular nanovalve.

[Structure: see text] The versatility of supramolecular chemistry has been exploited in constructing nanovalves based on mesoporous silica MCM-41 and the mutual recognition between secondary dialkylammonium ions and dibenzo[24]crown-8 (DB24C8). Naphthalene-containing dialkylammonium threads were tethered to the MCM-41, followed by loading with coumarin 460 and capping with DB24C8. Controlled re...

Towards an Operational Definition of Critical Thinking

This paper offers a state-of-the-art working definition for the concept of Critical Thinking (CT hereafter) in an attempt to provide a framework for the development of an operational definition for this complex concept. Having studied various definitions and models, proposed for CT by major figures in the field, the key defining features of this rich concept were identified and classified. Base...

Proximity nanovalve with large phase-tunable thermal conductance

An Operational Approach

Computer performance modeling of possibly complex computations running on highly concurrent systems is considered. Earlier work in this area either dealt with a very simple program structure or resulted in methods with exponential complexity. An efficient procedure is developed to compute the performance measures for series-parallel-reducible task systems using queueing network models. The proc...