Purpose To report long-term (>5 years) outcomes of plateau iris syndrome patients treated with argon laser peripheral iridoplasty (ALPI). Patients and Methods A retrospective chart review was performed on all patients with plateau iris syndrome treated with ALPI from 1996 to 2007. The study included 22 eyes from 22 patients with plateau iris after peripheral iridotomy that were followed for at least 1 year after ALPI. The primary outcome was incidence of needing any intraocular pressure (IOP)-lowering medications or surgery (either a filtering procedure or phacoemulsification). Demographic and baseline clinical data were summarized by mean (± standard deviation) or frequency (percentage). Snellen best-corrected visual acuity was converted to logMAR. The paired t-test was used to compare IOP changes, number of IOP-lowering medications, and best-corrected visual acuity from baseline to annual follow-up. Results Mean follow-up was 76 months. Only 2 (9%) eyes maintained an IOP <21 mm Hg without requiring medication or surgery. Seventeen (77%) eyes underwent surgery at an average of 49.1 ± 7.9 months after ALPI. Eight (36%) eyes underwent filtering surgery, and 9 (41%) eyes underwent phacoemulsification. Three months after cataract extraction, no eyes required IOP-lowering medication. Conclusions The beneficial effects of ALPI last for less than 4 years, with the majority of patients (77%) requiring surgery. Phacoemulsification alone was a successful treatment for plateau iris in our patient population.

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We studied the effect of lead content (x = 0.20−0.40) on the critical current density Jc (0 T, 77 K), irreversibility field H* (77 K), and microstructure of monocore, Ag-clad Bi1.8PbxSr2Ca2Cu3Oy (2223) tapes, finding that tapes with lower lead contents (x = 0.20–0.25) required higher processing temperatures (840 and 832 °C, respectively) to complete 2223 formation, as compared to the optimum 820 °C reaction temperature of the x = 0.30–0.40 tapes. We found that both the zero-field and the in-field properties correlated strongly to the phase purity with Jc (0 T, 77 K) reaching a maximum of ˜20 kA/cm2 for x = 0.30, and then decreasing with increasing lead content to ˜12 kA/cm2 for x = 0.40. H* (77 K) increased from ˜165 mT at x = 0.20 to ˜265 mT at x = 0.30, then declined to 195 mT at x = 0.40. Optimizing the lead content at x = 0.30 maximized both the connectivity and the flux pinning contributions to the critical current density.

The irreversibility field, H*, has been measured for a variety of mono-and multifilamentary ͑Bi,Pb͒ 2 Sr 2 Ca 2 Cu 3 O x ͑2223͒ tapes using two different transport current techniques. It is common to characterize the quality of 2223 tapes by their zero-field, 77 K critical current density ͓J c (0 T, 77 K͔͒, even though this ignores the fact that significant self-fields depress J c (0 T, 77 K) and the possibility that the in-field J c (B) characteristics may be optimized independently of the J c (0 T, 77 K) value. To provide more useful information, we propose a second characterization, that of the irreversibility field, H*. Having both H* and J c (0 T, 77 K) information helps in separating the two independent contributions that better connectivity and stronger flux pinning can make to the J c of a tape. We illustrate this point with results from a variety of mono-and multifilamentary Bi-2223/Ag tapes in damaged and undamaged conditions, which show that H* ͑77 K͒ can vary from ϳ100 to ϳ200 mT and not directly correlate with J c (0 T, 77 K). The two proposed protocols for H* measurement are robust and compatible with common transport measurement procedures. © 1997 American Institute of Physics. ͓S0003-6951͑97͒00352-5͔Both the zero-field, J c (0), and the in-field, J c (B), critical current densities of ͑Bi,Pb͒ 2 Sr 2 Ca 2 Cu 3 O x ͑2223͒ tapes must be improved to make applications economically feasible. J c is defined experimentally as J c ϭI c /A where I c is the critical current and A is the area of the whole ceramic cross section. However, this averaged, overall J c is most certainly an understatement of the maximum local J c because the current percolates through only a fraction of the cross-sectional area, A active . J c (0) contains significant contributions from current paths that include weakly linked grain boundaries, which are decoupled by small magnetic fields, and it is thus at least partially limited by self-fields generated by the transport current. However, J c (B) is strongly influenced by the strength of the flux pinning. At high fields, either intragranular 1-6 or intergranular 7,8 flux pinning becomes the main J c -limiting mechanism. Because different mechanisms determine J c (0) and J c (B), this leads us to believe that J c (B) may be optimized independently of J c (0). The irreversibility field, H*, is an increasingly common parameter used to measure flux pinning because it is strongly influenced by flux pinning. H* can be measured by several magnetization and transport current techniques. Previous work [8][9][10] has shown that individual composites often show a direct correlation between H* and J c (0). However, as we have accumulated a larger database of H* and J c (0) characterizations, we have found that there is no universal correlation and we, therefore, conclude that it is vital to characterize both the flux pinning and zero-field properties, if the highest performance is to be developed in BSCCO-2223 tapes.When H* is measured by magnetization, the magnetization signal is averaged ov...

We studied the influence of the intermediate rolling deformation on the residual crack network and critical current density in multifilamentary (Bi,Pb)2Sr2Ca2Cu3Ox (2223) tapes. Although an intermediate rolling step between heat treatment is generally beneficial in raising the critical current density, it also has the negative effect of causing cracking. Cracking was evaluated both by magneto optical imaging and by ultrasonic fracture of extracted filaments. We found that the characteristic fragment size was sensitive to both roll diameter and reduction percentage, decreasing from ~210 µm for a 10% reduction to ~115 µm for a ~20% reduction with 152 mm diameter rolls. At a constant 10% reduction, the fragment size decreased from ~210 µm to ~140 µm when changing from 152 mm to 38 mm diameter rolls. We conclude that intermediate deformation is positive in so far as it decreases the filament porosity, but that it cannot reduce this too much without introducing more cracking than can be healed in subsequent heat treatment. The critical current density thus maximizes at an intermediate deformation that counterbalances these two oppositely directed influences on the filament connectivity.

Abstract-We have studied the effect of wire drawing and cold rolling on the texture development of precursor (Bi,Pb)2Sr2CaCu20, (2212) phase and its influence on the subsequent (Bi,Pb)2Sr2Ca2Cu30, (2223) phase texture in Ag-clad tapes. A mixture of (Bi,Pb)zCu04 and SrCaCu03 powders having an overall 2223 composition was reacted to form the 2212 phase at different stages of deformation. X-ray diffraction peak height analysis was used to quantify the 2212 texture F2212=

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