Extension of Methane Emission Rate Distribution for Permian Basin Oil and Gas Production Infrastructure by Aerial LiDAR.

Aerial LiDAR measurements at 7474 oil and gas production facilities in the Permian Basin yield a measured methane emission rate distribution extending to the detection sensitivity of the method, 2 kg/h at 90% probability of detection (POD). Emissions are found at 38.3% of facilities scanned, a significantly higher proportion than reported in lower-sensitivity campaigns. LiDAR measurements are analyzed in combination with measurements of the heavy tail portion of the distribution (>600 kg/h) obtained from an airborne solar infrared imaging spectrometry campaign by Carbon Mapper (CM). A joint distribution is found by fitting the aligned LiDAR and CM data. By comparing the aerial samples to the joint distribution, the practical detection sensitivity of the CM 2019 campaign is found to be 280 kg/h [256, 309] (95% confidence) at 50% POD for facility-sized emission sources. With respect to the joint model distribution and its confidence interval, the LiDAR campaign is found to have measured 103.6% [93.5, 114.2%] of the total emission rate predicted by the model for equipment-sized emission sources (∼2 m diameter) with emission rates above 3 kg/h, whereas the CM 2019 campaign is found to have measured 39.7% [34.6, 45.1%] of the same quantity for facility-sized sources (150 m diameter) above 10 kg/h. The analysis is repeated with data from CM 2020-21 campaigns with similar results. The combined distributions represent a more comprehensive view of the emission rate distribution in the survey area, revealing the significance of previously underreported emission sources at rates below the detection sensitivity of some emissions monitoring campaigns.

Comparison of Phacoemulsification Grooving Efficiency in Longitudinal vs Transversal Handpieces.

Purpose: To determine the difference, if any, in grooving efficiency at various settings on the Whitestar Signature Pro phacoemulsification (phaco) system. Methods: Cataractous lenses were simulated by exposing porcine lenses to formalin for 2 hours. A total of 120 lenses were analyzed at various power settings on both longitudinal and transversal handpieces. Twenty trials each were performed with power set to 25%, 50%, and 75% on both handpieces. A Whitestar Phaco Handpiece System was used to provide longitudinal power, and a Whitestar Signature Ellipsis Handpiece provided transversal power. Lenses were placed within a plastic chamber and grooved by an investigator blinded to settings. A second investigator recorded times and adjusted settings. The Whitestar Signature Pro phaco system was used for grooving. Results: There was no significant difference in grooving times between the longitudinal and transverse handpieces at any power setting (P > 0.05). There was a significant decrease in grooving times when comparing the 25% power setting with the 75% power setting for the transversal handpiece (P=0.021). Conclusion: Both longitudinal and transversal handpieces on the Whitestar Signature Pro phaco system produce similar results to one another at each power setting. There is a general trend toward shorter grooving times, reflecting greater efficiency, at higher power settings. Grooving efficiency on the transversal handpiece may be more affected by changes in the power settings as compared with the longitudinal settings.

Temperature Change of Ophthalmic Viscosurgical Devices in a Bi-Chamber Set-Up at a Flow of 0 and 20mL/min.

Purpose: To understand the role of ophthalmic viscosurgical devices (OVDs) in corneal incision contracture (CIC). Specifically, the aim was to evaluate with the tip of the phacoemulsification needle free of OVD, how various OVDs near the tip and sleeve may transmit thermal energy to the incision site. Methods: A small chamber was filled with balanced saline solution (BSS), and a thin membrane was placed on the surface. OVD was placed atop the membrane. A temperature probe was placed in the OVD, while the handpiece pierced the membrane. The experiment was run both with and without flow and vacuum. Temperature measurements were gathered for each of the OVDs at four separate time points at 0 and 20mL/min flow. Results: As expected, there was a more pronounced temperature increase in all test groups with no fluid flow. While the temperature increase was not significantly different from BSS for any of the OVDs tested at either 0 or 20mL/min, Viscoat showed the most variable results at both flow settings. Conclusion: As long as the phaco tip is not in OVD, residual OVD near the incision is not exothermic and so not an additional risk for CIC.

Effect of low and passive flow on OVD thermal properties during phacoemulsification.

OBJECTIVE: To study the thermal properties and response magnitude of a forced-infusion phacoemulsification machine on 4 ophthalmic viscosurgical devices (OVDs). DESIGN: Experimental study. METHODS: A phacoemulsification tip, thermocouple, and gauge were placed into an artificial anterior chamber with balanced saline solution (BSS) or approximately 0.1 mL of OVD. Once the thermocouple measured a consistent temperature, the pedal was engaged for 60 seconds; then the tip was removed. The machine was cooled for 5 minutes and flushed with BSS to return to baseline. This was repeated 10 times for each OVD. The research consisted of 2 scenarios: vacuum-blocked flow rate and low aspiration flow rate. RESULTS: All OVDs showed greater temperature changes than BSS. In the vacuum-blocked scenario, these increases were statistically significant. The medium viscosity dispersive OVD (DiscoVisc) reached temperatures exceeding 60°C. In the low-flow scenario, HEALON5 and DisCoVisc were significantly different at 5 seconds and only HEALON5 at 10 seconds. No temperature increases over BSS were greater than 1.0°C. CONCLUSIONS: The dispersive, cohesive, and viscoadaptive OVDs demonstrated higher temperature changes than BSS but did not reach the threshold for corneal incision contracture. The study team verified the need for at least a minimal flow rate before ultrasound, which is especially evident in the first 10 seconds, because a flow rate of only 20 mL/minute mitigated OVD-related thermal effects. Understanding thermal responses enables corneal incision contracture risk reduction.

Effect of longitudinal and torsional ultrasound on corneal endothelial cells: experimental study in rabbit eyes.

PURPOSE: To compare corneal endothelial damage from longitudinal and torsional ultrasound during phacoemulsification. SETTING: John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA. DESIGN: Experimental study. METHODS: 9 New Zealand white rabbits underwent bilateral surgery. After incision, the Intrepid Balanced Tip of the Centurion Ozil handpiece was inserted into the anterior chamber, and the following settings were used: 50 mL/min flow, 70 mm Hg intraocular pressure, 600 mm Hg vacuum, and 60% longitudinal (1 eye) or torsional (contralateral eye) ultrasound for 30 seconds. Cumulative dissipated energy (CDE) was noted. After euthanasia and enucleation, the corneas were removed, stained with trypan blue/alizarin red, and photographed (400× photographs from 5 specific areas and 1 overview photograph from each corneal button). The ImageJ program was used to evaluate cell damage and loss in the photographs obtained from each cornea. RESULTS: Cavitation bubbles around the phacoemulsification tip were generally observed in the longitudinal group. CDE was 17.4 ± 0.58 and 6.93 ± 0.15 in the longitudinal and torsional groups, respectively (P = .003). The percentage of intact cells was statistically higher in the torsional group (94.22% ± 5.99% vs 56.85% ± 22.29%), and the percentage of lost cells was statistically higher in the longitudinal group (42.10% ± 22.02% vs 4.97% ± 6.23%) (P = .003). This was observed in the analysis of the 400× photographs and the overview photographs. CONCLUSIONS: This study suggests that torsional ultrasound was associated with significantly less corneal endothelial cell damage than classical longitudinal tip motion, providing further insight on mechanisms of corneal endothelial damage during phacoemulsification.

Effect of phacoemulsification fluid flow on the corneal endothelium: experimental study in rabbit eyes.

PURPOSE: To quantify the damage to the corneal endothelium from the flow of a balanced salt solution during phacoemulsification. SETTING: John A. Moran Eye Center, University of Utah, Salt Lake City, Utah. DESIGN: Experimental study. METHODS: 12 New Zealand white rabbits received bilateral surgery. 6 eyes served as controls with no irrigation (incision only). In 18 eyes, the Intrepid Balanced tip of the Centurion Ozil (Alcon Laboratories, Inc.) handpiece was inserted into the anterior chamber for continuous irrigation at 50 mL/min with either 250 or 500 mL of balanced salt solution. After killing humanely and enucleation, the corneas were removed, stained with trypan blue-alizarin red, and photographed in a standardized manner (×400 photographs from 5 specific areas and 1 overview photograph from each corneal button). The ImageJ program was used to evaluate cell damage and loss in the photographs obtained from each cornea. RESULTS: Analysis of the ×400 photographs showed no statistically significant differences between control, 250 mL, and 500 mL groups in the percentage of intact, damaged, or lost cells (P = .896, .851, and .972 respectively). For the overview photographs, the differences in areas of intact and damaged cells among the groups were statistically significant, likely because of the peripheral areas of damage related to touches between the phacoemulsification tip and the endothelium during irrigation. CONCLUSIONS: The volume of balanced salt solution flow alone did not seem to be a major contributing source of endothelial cell damage and loss, providing further insight into mechanisms of corneal endothelium damage during phacoemulsification.