ABSTRACT
High-T(c) Josephson junctions were fabricated by nanolithography using focused ion beam (FIB) milling and ion implantation. The junctions were formed in a YBa2Cu3O7-x, thin film in regions defined using a gold-film mask with 50-nm-wide (top) slits, engraved by FIB. The focused ion beam system parameters for dwell time and passes were set to remove gold up to a precise depth. 150 keV oxygen ions were implanted at a nominal dose of up to 5 x 10(13) ions/cm2 into YBa2Cu3O7-x microbridges through the nanoscale slits. The current-voltage curves of the ion implantation junctions exhibit resistive-shunted-junction-like behavior at 77 K. The junction had an approximately linear temperature dependence of critical current. Shapiro steps were observed under microwave irradiation. A 50-nm-wide slit and 0-20-nm-thick buffer layers were chosen in order to make Josephson junctions due to the V-shape of the FIB-milled trench.
Subject(s)
Ions/chemistry , Nanostructures/chemistry , Nanotechnology/methods , Electrochemistry , Gold/chemistry , Metals/chemistry , Microscopy, Electron, Scanning , Oxygen/chemistryABSTRACT
OBJECTIVE: To determine the incidence and type of extraocular motility disturbance after double-plate Molteno implantation. METHODS: In a prospective clinical series, we evaluated preoperative and postoperative ocular motility at 3 and 6 months in 24 eyes of 24 patients undergoing double-plate Molteno implantation. Visual acuity, motility testing, and subjective and objective diplopia were evaluated at each examination. RESULTS: Within the first 6 months postoperatively, new or worse strabismus developed in 11 (46%) of the 24 study patients. Three of the 11 patients had a generalized restriction of the superior rectus and the superior oblique muscles, all of which persisted 6 months after surgery. Four patients had clinical features consistent with an acquired Brown syndrome, and 6 months after surgery, 3 of the 4 patients had a residual deviation, although the deviation in 1 patient resolved. A superior oblique palsy developed in 3 patients, and a lateral rectus palsy developed in 1 patient. All 4 of the muscle palsies resolved or were resolving during the follow-up period, which ranged from 6 to 12 months. CONCLUSIONS: Extraocular motility disturbances are not rare after double-plate Molteno surgery. Muscle palsies, acquired Brown syndromes, and generalized restrictions occurred in similar proportions. CLINICAL RELEVANCE: Patients should be counseled before Molteno surgery concerning the risk of strabismus and diplopia.
