The present invention provides a web containing superfine microfibers. The opening and the obstruction are sized such that, when the obstruction is disposed in the blocking position with the streamer passed through the opening and the safety pin disposed in the receiving element, the obstruction is irremovable from the blocking position until the safety pin is removed from the receiving element. In some embodiments, each of the links connects exactly two of the nodes. A lens is provided having a numerical aperture and focal length sufficient to focus the beam to a diameter of less than 20 microns on the sample surface. The apparatus includes an annular gas ring with multiple outlets for introducing a cleaning gas into the process chamber, and the method includes using the gas ring to introduce a cleaning species from a remote plasma source into the processing chamber. The LTE network comprises the relay node and the DeNB.