Fill Gas Research Articles

The System Analysis of Decision Support in the Development of a Network of Gas Filling Stations

The article describes the elements of the project for the development of software tools for automating decision support processes when planning measures for the development of a regional network of automobile gas filling compressor stations: diagrams of the design and construction of gas filling stations; the problem of finding places for the rational placement of gas filling stations according to the criteria of process (industrial equipment parameters), structure, cost and topology optimality. The functional diagram contains a description of all information flows and control flows. A variant of the solution of the problem of placing objects of transportation with natural gas, using an algorithm of directed enumeration of variants of solutions, is proposed.

Development of aHg-free UV light source incorporating a Kr/Br2 gas, and its application for wastewater treatments.

Mercury lamps are typically the major light sources in water treatments. However, the use of mercury has raised some concerns with regard to the Minamata Convention on Mercury. As such, Hg-free microwave discharged electrodeless lamps (MDELs) that incorporate a rare gas and a halogen gas (R/H-MDEL) have been investigated with such Hg-free mixture filler gases as Kr/Cl2, Xe/Cl2, and Kr/Br2 (R/H). Of these, only the Kr/Br2-MDEL lamp is self-ignited at an inner pressure of 15Torr when irradiated with microwave radiation. Accordingly, a novel Kr/Br2 three-layer MDEL (Kr/Br2-MDEL) photoreactor was fabricated to assess the optimal gas composition and gas pressure toward its performance vis-à-vis thetreatment of model wastewaters contaminated with the tartrazine dye in aqueous media and with Escherichia coli (E. coli) bacteria. The extent of degradation of the tartrazine dye and sterilization of E. coli increased with irradiation time, with microwave radiation power (100, 200, and 300W), and with increased sample flow rate 0.4 L min‒1 to 0.8 L min‒1. The tartrazine-contaminated wastewater was treated at a flow rate of 0.4 L min‒1 for 60min of microwave irradiation by three different protocols that resulted in UV (62%) >> UV/ROS (24%) > ROS (0%); ROS denotes reactive oxygen species. After 5min irradiation of the E.coli wastewater, also at 0.4 L min‒1, the order was UV (99.5%) ≈ UV/ROS (99.3%) >> ROS (14.5%). For comparison, the photosterilization of E. coli with an equivalent Hg/Ar-MDEL light source was also nearly complete (99.7%). Thus, the suitability of the environmentally friendlier Kr/Br2 gas fill to replace Hg/Ar filler gas in MDELs for the photoelimination of organic pollutants and microbial disinfection in aqueous media has been demonstrated.

Depletion of atomic hydrogen in a high power helicon discharge

Depletion of the ground state atomic hydrogen density has been directly measured using two-photon laser-induced fluorescence in a high-density helicon plasma. The depletion is correlated with the plasma pressure becoming increasingly higher than the neutral gas fill pressure. Spatially resolved measurements show depletion of atomic hydrogen in the centre of the discharge chamber. Temporally resolved measurements display a replenishment of atomic hydrogen in the plasma afterglow at high plasma densities in comparison to the typical two-step decay at lower plasma densities.

Effect of krypton admixture in deuterium on neutron yield in a megaampere dense plasma focus

Experiments on a MA-class Dense Plasma Focus (DPF) device have been carried out to investigate changes in neutron production by adding moderate amounts of krypton to a deuterium fill gas. The neutron yield from Z-pinch devices, including DPFs, conventionally scales as the peak current to the fourth power. However, a dramatic drop-off from ∼I4 scaling occurs above 3 MA, which recent modeling [D. T. Offermann et al., Phys. Rev. Lett. 116, 195001 (2016)] attributed to the transition in the predominant neutron production mechanism from beam-target fusion to thermonuclear fusion. Previously, the addition of Kr (and other high-Z) dopants has been shown to enhance beam-target fusion yields at currents below 300 kA, with optimal concentrations at 1%–2% Kr, whereas here we show that the optimal concentration of Kr at the MA level is near 0.1% by volume—elucidating a trend in the optimal Kr doping concentration as a function of the device scale. The neutron time-of-flight data reveal that Kr doping creates shorter and more intense neutron bursts, likely due a tighter but unstable pinch, highlighting a key trade-off for Kr doping.

Application of cross-beam energy transfer to control drive symmetry in ICF implosions in low gas fill Hohlraums at the National Ignition Facility

Cross beam energy transfer (CBET), invoked by setting a wavelength difference, Δλ, between inner and outer beam cones, can be used to increase the drive on the waist in indirectly driven inertial confinement fusion experiments at the National Ignition Facility (NIF). Historically, hot spot symmetry control in capsule implosions in high (≥0.9 mg/cm3 4He) gas fill Hohlraums was enabled by substantial CBET. However, these implosion designs suffered from inflight symmetry swings, high SRS backscatter on the inner cones, and significant hot electron generation posing a threat to DT fuel preheat. Subsequent experiments in larger, low (≤0.6 mg/cm3 4He) gas fill Hohlraums demonstrated round implosions by varying the inner cone fraction throughout the laser drive at Δλ = 0 Å while keeping backscatter and hot electron generation very low. To enable driving larger capsules at a given Hohlraum size, additional tools for implosion symmetry control are required. With this goal in mind, this paper presents a detailed experimental study of using CBET in low gas fill Hohlraums near NIF's current peak power capability. We find a ∼2.5× higher sensitivity of the P2 Legendre mode with respect to Δλ changes compared to that of high gas fill designs. We attribute this observation to the fact that backscatter remains very low and that CBET remains in a linear regime, as suggested by simulations. As a result, a much smaller Δλ of order 1 Å is sufficient for sustaining implosion symmetry while keeping laser-to-Hohlraum coupling high and hot electron generation very low. While this study used plastic ablator capsules, our findings can be generalized to other ablator materials and, hence, show great promise for using wavelength detuning as a strong lever for implosion symmetry control in future low gas fill designs that require smaller case to capsule ratios in order to increase the energy coupled to the capsule.

Dynamics of a Crankshaft Mechanism under the Pressure of a Viscous Gas

We study an initial–boundary value problem with free boundary for one-dimensional equations of viscous gas dynamics. The problem models the motion of a crankshaft mechanism under gas pressure. It is assumed that the gas fills a cylinder, which is modeled by the interval $$[0,1]$$ . A variable point $$a(t)\in[0,1]$$ models a piston moving inside the cylinder. The piston is assumed to be connected to a planar three-link crankshaft mechanism. We also assume that a velocity distribution on the boundary of the cylinder and a density distribution on gas inflow segments are given. The gas motion is described by the one-dimensional Navier–Stokes equations of viscous compressible fluid dynamics. It is required to determine the joint motion of the gas and crankshaft mechanism. We prove that this problem has a weak renormalized solution.

The role of hydrogen gas bubble in hydrophobic properties in mixed micro layer (Al2O3+Mg)

Purpose: To find out more about the role of hydrogen gas bubbles in improving the hydrophobic nature of a layer, especially in the layers of microparticles Alumina (Al2O3) with Magnesium (Mg). Design/methodology/approach: The method used is an experimental method by first conducting the SEM-Edx test, testing the content of the elements in the waxy layer and observing the topographic shape on the surface of the taro leaves. Then prepare a mixture of Alumina micro particles with Magnesium to investigate the hydrophobicity of the taro leaves. The mixed presentations between Alumina and Magnesium are: (0, 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100%). Findings: The results of this study found three conditions of the Alumina and Magnesium mix layer when in contact with a droplet, namely: Hydrophobic conditions occur when the surface structure of the rough mixed micro layer forms micro crevices, then bubbles of hydrogen gas fill it to form trapped gases. When droplets come in contact with the surface of the mixed layer the effect of the gas being trapped is very effective at creating hydrophobic properties. While the transition conditions occur when more and more hydrogen gas bubbles along with the increasing percentage of Mg and the opposite occurs in micro particle fissures. Bubbles fill the micro-gap space fully so that the tops of the micro particles are covered by bubbles. This causes the droplet surface tension to weaken, so the droplet contact angle decreases. Furthermore, hydrophilic conditions occur when the micro gap is getting narrower as the percentage of Mg increases and the formation of hydrogen gas bubbles increases. The high level of bubble density in the micro gap closes the peaks of the micro particles, which results in the surface tension of the droplet getting weaker. In this weak surface tension condition, the hydrogen bubble can break through the droplet surface tension and change its hydrophobic nature to hydrophilic. Research limitations/implications: This research is limited to the hydrophobicity of Alumina and Magnesium materials, mainly to investigate the role of hydrogen gas in supporting the hydrophobic nature of taro leaves (Colocasia esculenta). Practical implications: The practical implication in this study is the use of hydrophobic membranes which are widely applied to filtration. Originality/value: Discovered the composition of a membrane mixture of Alumina (Al2O3) and Magnesium (Mg) to create hydrophilic and hydrophobic conditions.

Temperature distributions and gradients in laser-heated plasmas relevant to magnetized liner inertial fusion.

We present two-dimensional temperature measurements of magnetized and unmagnetized plasma experiments performed at Z relevant to the preheat stage in magnetized liner inertial fusion. The deuterium gas fill was doped with a trace amount of argon for spectroscopy purposes, and time-integrated spatially resolved spectra and narrow-band images were collected in both experiments. The spectrum and image data were included in two separate multiobjective analysis methods to extract the electron temperature spatial distribution T_{e}(r,z). The results indicate that the magnetic field increases T_{e}, the axial extent of the laser heating, and the magnitude of the radial temperature gradients. Comparisons with simulations reveal that the simulations overpredict the extent of the laser heating and underpredict the temperature. Temperature gradient scale lengths extracted from the measurements also permit an assessment of the importance of nonlocal heat transport.

Wireless ‘under the skull’ epidural EEG and behavior in piglets during nitrous oxide or carbon dioxide gas euthanasia

Consciousness is central to animal welfare concerns. Its assessment is most often conducted based on behavior, with a poor understanding of the correspondence between behavior and the neurobiological processes that underlie the subjective experience of consciousness. Recording of brain electrical activity using electrodes placed under the skull improves EEG recording by minimizing artifacts from muscular or cardiac activities, and it can now be combined with wireless recording in free-moving animals. This experiment investigated the correspondence between wireless ‘under the skull’ epidural EEG and the behavior of 18 five-week-old female piglets undergoing nitrous oxide (N2O) or carbon dioxide (CO2) gradual fill gas euthanasia at 25% replacement rate per minute of the chamber volume. Piglets exposed to CO2 had a peak in EEG total power (‘Ptot’) during the flailing stage, whereas piglets exposed to N2O had a higher EEG 95% spectral edge frequency (‘F95’) during their initial explorative behavior phase and a drop in EEG median frequency (‘F50’) after loss of posture. Loss of posture without righting attempt, as the last behavioral state observed during euthanasia, preceded the onset of transitional EEG on average by 0.9 and 3.1 min (for CO2 and N2O treatments, respectively), and the onset of isoelectric EEG by 4.5 and 6.2 min (for CO2 and N2O treatments, respectively). Paddling movements occurred shortly before and during transitional EEG but never during isoelectric EEG, whereas gasps persisted after the EEG had become isoelectric. The dynamics of EEG spectral changes were complex to interpret in relation to the degree of consciousness, but isoelectric EEG as an unequivocal indicator of unconsciousness appeared several minutes after loss of posture with no righting attempt. This leaves a window of uncertainty in regards to the potential for consciousness after loss of posture during gradual fill gas euthanasia in piglets.

High-sensitivity gas pressure sensor based on a multimode interferometer using hollow-core tube lattice fiber.

A non-diaphragm fiber gas pressure sensor based on a multimode interferometer (MI) using a hollow-core tube lattice fiber (HC-TLF) as a gas cell is proposed and experimentally demonstrated. The sensor is fabricated by fusion splicing a sandwich structure of a graded-index multimode fiber, HC-TLF, and lead-in/out single mode fiber. Several side-holes are drilled by using a femtosecond laser on the side wall of the HC-TLF to allow gas in and out of the fiber. The positions of side-hole in HC-TLF have been investigated during the experiments, which indicate that the highest gas pressure sensitivity existed as the side-hole located in the gap between adjacent cladding holes of the HC-TLF. The proposed structure exhibits a high sensitivity of 8.1 nm/MPa with the average gas fill time of 2.2 s. This sensor also has low temperature sensitivity and low temperature cross sensitivity of 12.3 pm/°C and 1.5 kPa/°C as the temperature rises to 400°C. In addition, the advantages of the gas pressure sensor, such as small size, rapid response, low temperature cross sensitivity, and simple fabrication process, make it suitable for high-pressure measurement in harsh conditions, e.g., downhole and ocean bottom.

Switching Behavior of a Gas-Filled Model DC-Contactor Under Different Conditions

The switching behavior of gas-filled contactors was investigated using a model switch. High-speed imaging and spectroscopy provided information regarding the characteristics of the arc plasma. The impact of external magnetic fields, fill gas, fill pressure, and current amplitude was investigated. The most important factor, influencing the switching behavior for currents below 100 A, is provided by external magnetic fields, which increase arc voltage and arc instability considerably. The observed changes of the side-on profiles of the characteristic emission lines indicate changes in particle densities and arc temperature.

Ferrite-free closed-loop inductively-coupled low mercury pressure UV lamp

Characteristics of ultraviolet (UV) radiation (254 nm) sources employing ferrite-free inductively-coupled low pressure mercury discharge excited in the closed-loop quartz tube with the inner diameter (ID), dt = 16,6 mm and the length, Λpl = 815 mm were experimentally studied. Discharge was maintained at a frequency of 1,7 MHz and RF powers, Plamp = 95–170 W, in the mixture of mercury vapor (~7–8 mTorr) and buffer gas fill (Ar, 30%Ne + 70%Ar) at pressures of 0,7 and 1,0 Torr. A 3-turn induction coil made from low loss Litz wire (resistivity, ρw = 1,4 × 10–4 Ω cm−1, wire diameter, dw = 1,5 mm) was disposed on the lamp surface along the closed-loop tube perimeter. As lamp RF power increased from 95 to 170 W, induction coil power losses, Pcoil, decreased from 7–9 to 3–4 W while coil power efficiency, ηcoil = 1- (Pcoil/Plamp), grew from 92 to 98%. Lamps with buffer gas at pressure of 1,0 Torr, operated at plasma RF power, Ppl = 105–150 W, had high plasma UV radiation generation efficiency, η254pl, max = Φ254/Ppl = 67%–68%, while lamp UV radiation generation maximal efficiency, η254, max = ηcoilη254pl, max, had slightly lower values of 63%–66%.

Measurement and parameterization of sub-1 eV ion temperatures in a helium plasma confined by a magnetic mirror

Using a magnetic mirror plasma device, helium ion temperatures were investigated using high resolution Doppler spectroscopy of the He II line at 468.6 nm. The objective was to improve the quality of fits to Langmuir probe data. Measured temperatures, which represent an average value over a line of sight, ranged from 0.07 eV to 0.32 eV with higher values reached in stronger magnetic fields. An analytic expression for the line of sight integral of a variable width Gaussian signal is presented, and it is demonstrated that the integrated signal can, in practice, be accurately fitted by a single Gaussian line shape. A large number of spectra was acquired using a randomized experimental design with four independently controllable engineering variables and three discrete magnetic fields. Separate parameterizations of the results for each magnetic field in terms of the engineering variables showed that the data could already be well fitted using only the plasma current as a predictor. The fit to the ion temperature data was significantly improved when both the plasma current and filament bias voltage were used as predictors. The helium gas fill pressure had negligible predictive value for the ion temperature. (figures in this article are in colour only in the electronic version).

The nuclear architecture of NGC 4151: on the path toward a universal outflow mechanism in light of NGC 1068

ABSTRACT We report near-infrared integral field spectroscopic observations of the active galactic nucleus NGC 4151 with archive data from the NIFS-Gemini North Telescope. We have selected best-seeing observations (≲0.3 arcsec) that, allied to our methodology of image processing techniques, show structures with spatial resolution comparable to those of the HST. The intricate outflow of NGC 4151 is revisited in light of the results found for NGC 1068, in a previous work, and a very similar dynamic is found: the low-velocity [Fe ii] emission depicts the glowing walls of an hourglass structure, while the high-velocity gas fills its volume. From this finding, we show that the misalignment between the jet and the NLR is not a projection effect, as previously thought. A molecular outflow is detected for the first time in this galaxy and, just like in NGC 1068, the transition between the molecular and the ionized gas phases comes from the fragmentation of molecular cavity walls into bullets of ionized gas exposed to the central source. Furthermore, it is suggestive that the same geometrical dichotomy between the cones seen in NGC 1068 is found here, with one side, where the cavity is disrupted by the AGN, being more extended than the other. Finally, a new spatial correlation between the high-velocity [Fe ii] and the soft X-ray emission of [Ne ix] is found, which is unexpected given the difference between their ionization potentials.

Symmetric fielding of the largest diamond capsule implosions on the NIF

We present results for the largest diamond capsule implosions driven symmetrically on the National Ignition Facility (NIF) (inner radius of ∼1050 μm) without the use of cross beam transfer in cylindrical Hohlraums. We show that the methodology of designing Hohlraum parameters in a semi-empirical way using an extensive database resulted in a round implosion. In addition, we show that the radiation flux symmetry is well controlled during the foot of the pulse and that swings in P2 symmetry between the inflight dense shell and hot spot are within ±4 μm and that swings around peak compression are also within the symmetry specification of ±4 μm. We observed a stronger dependence of symmetry on the capsule scale than previously observed and also observed enhanced inner beam propagation for experiments using a gas fill density of 0.3 mg/cm3 and 1000 μm inner radius capsules. We have observed sufficient symmetry and mass remaining at near full NIF power and energy, up to 480 TW and 1.9 MJ, with little laser–plasma interactions (low laser backscattered light) and predict that this design could support extended NIF energy of up to 2.1 MJ.

Personalized Ventilation to Multiple Patients Using a Single Ventilator: Description and Proof of Concept.

To design and test a ventilator circuit that can be used for ventilation of two or more patients with a single ventilator, while allowing individualization of tidal volume, fractional concentration of oxygen, and positive end-expiratory pressure to each patient, irrespective of the other patient's respiratory system mechanics. Description and proof of concept studies. Respiratory therapy laboratory. Ventilation of mechanical test lungs. Following a previously advocated design, we used components readily available in our hospital to assemble two "bag-in-a-box" breathing circuits. Each patient circuit consisted of a flexible bag in a rigid container connected via one-way valve to a test lung, along with an inline positive end-expiratory pressure valve, connected to the ventilator's expiratory limb. Compressed gas fills the bags during "patient" exhalation. During inspiration, gas from the ventilator, in pressure control mode, enters the containers and displaces gas from the bags to the test lungs. We varied tidal volume, "respiratory system" compliance, and positive end-expiratory pressure in one lung and observed the effect on the tidal volume of the other. We were able to obtain different tidal volume, dynamic driving pressure, and positive end-expiratory pressure in the two lungs under widely different compliances in both lungs. Complete obstruction, or disconnection at the circuit connection to one test lung, had minimal effect (< 5% on average) on the ventilation to the co-ventilated lung. A secondary circuit "bag-in-the-box" system enables individualized ventilation of two lungs overcoming many of the concerns of ventilating more than one patient with a single ventilator.

Orbital Magnetic Resonance Imaging Demonstrates Better Contact between the Gas and Anterior Inferior Retina in Side versus Face-Down Position

To demonstrate the relationship between an intraocular gas bubble, the retina, and the residual intraocular fluid in different head positions using orbital magnetic resonance imaging (MRI) in 3 patients who underwent pars plana vitrectomy (PPV) with gas tamponade. Novel study. Patients undergoing PPV with gas-fluid exchange (sulfurhexafluoride [SF6] or perfluoropropane [C3F8]). Magnetic resonance imaging scans were obtained in 3 patients undergoing PPV with gas-fluid exchange (SF6 or C3F8). All surgeries were performed by a single surgeon (E.D.M.). On the first postoperative day, the volume of intraocular gas fill was estimated separately by 2 surgeons (A.H. and E.D.M). Four orbital MRI scans were obtained from different head positions, including face up (supine), face down (prone on a massage pillow), flat on the right side, and flat on the left side. Relationship between the gas bubble and residual vitreous fluid. The MRI images demonstrated, with excellent contrast, the gas and fluid locations in the vitreous cavity in all scans. The relationship between the gas bubble and residual vitreous fluid showed a rapid shift when the patient's head position changed. The MRI images demonstrated that with both 70% gas fill and 95% gas fill, lying on the side can give better support to the inferior retina than face-down positioning. The images demonstrated the importance of accurate head positioning, because a slight change in head position resulted in inadequate contact between the anterior inferior retina and the gas bubble. To our knowledge, this is the first time that the relationship between an intraocular gas bubble and contact with the retina has been evaluated in different head positions invivo using MRI imaging. The MRI images demonstrated that side positioning gives better contact between the gas bubble and the inferior and anterior retina than prone positioning even when the gas fill is only 70% of the vitreous cavity.

Understanding ICF hohlraums using NIF gated laser-entrance-hole images

The newly available ns-gated laser-entrance-hole (LEH) imager on the National Ignition Facility provides routine, non-perturbative measurements of the x-ray emission from laser-heated plasmas inside the hohlraum as viewed at 19° to the hohlraum axis through one of its LEHs. Multiple images are acquired for a series of times and filter-selected x-ray energy bands within a single shot. The images provide time dependent data on phenomena including the effective radius of the LEH, the length of the gold-plasma “bubble” evolving off the interior wall surface heated by the outer beams, the evolving radius of the x-ray heated hohlraum wall, and the radius of the ablation front of the fusion capsule. These measurements are explained and illustrated with sample data. These techniques are then applied to understand hohlraum behavior as a function of gas fill. For hohlraums with helium gas fill densities of 0.15 to 0.30 mg/cm3, synthetic images computed from simulations agree well with experimental gated LEH images when an inhibited heat transport model [Jones et al., Phys. Plasmas 24, 056312 (2017)] is used. This model can be adjusted to reproduce the expansion rate of the laser-heated plasma bubble in such a way as to improve agreement with the images. At the higher 0.6 mg/cc gas fill, the experimental images show more pronounced 3D features, resulting in slightly less good agreement with the 2D simulations.

Diffusion process simulation and ventilation strategy for small-hole natural gas leakage in utility tunnels

The utility tunnel provides enough spaces, dry environment, better monitoring and maintenance for municipal pipelines. When gas pipelines are incorporated into the utility tunnel, the flammability and explosion property of the natural gas would threaten its safe operation. At present, the safety prevention technology and the safety design specifications for gas pipeline in utility tunnels are not mature. To investigate the gas diffusion characteristics in the utility tunnel, and to propose an emergency accident ventilation strategy, in this paper, the mechanism of small-hole gas leakage diffusion under natural and mechanical ventilation is studied, and the influential factors are simulated and analyzed in detail using the Fluent software. The results indicate that under the natural ventilation, the gas spreads to the whole compartment at the leakage time of 300 s, while under the normal ventilation scheme, the leaked natural gas fills the downstream half of the compartment at the time of 120 s. When the leak size and pressure increase, the alarm response time shortens, the concentration of test point increases, and the danger zone expands. To prevent alarm failure and gas gathering for the near-outlet leakage, it is recommended that the last detector and the air outlet should be placed as close as possible to the fireproof wall. In addition, when a leak occurs, increasing the air change rate can greatly reduce the overall gas concentration. When the leak size is no more than 5 mm, and the pipeline pressure is lower than 0.4 MPa, the minimum accident ventilation scheme could guarantee the safe operation of the utility tunnel. When the pipeline pressure grows to 0.8 MPa, the effective air change rates of the emergency accident ventilation are 15 times/h, 18 times/h, and 24 times/h, respectively for the leak sizes of 4 mm, 5 mm, and 6 mm. Moreover, for the pipeline pressure of 1.6 MPa, the effective air change rates are 21 times/h, 30 times/h, and 36 times/h, respectively for the leak sizes of 4 mm, 5 mm, and 6 mm.

Factors impacting gas fill after microincision vitrectomy surgery combined with fluid-gas exchange.

PURPOSE:The objective of the study was to investigate possible factors influencing gas fill after microincision vitrectomy surgery (MIVS) combined with fluid–gas exchange.MATERIALS AND METHODS:This was a retrospective chart review of patients who underwent MIVS combined with fluid–gas exchange (20% C3F8) from February 2017 to December 2017.RESULTS:Sixty-one eyes of 58 patients were identified. The mean age was 59.97 ± 9.65 years. The mean gas fill percentage was 76.28% ± 14.29% on day 1, 65.49% ±13.65% on day 3, 60.03% ± 14.53% on day 4, and 43.9% ± 20.88% on day 7 postoperatively. Compared to phakic eyes, eyes that were pseudophakic prior to surgery had a lower gas fill on days 1–3, but the difference did not reach significance on day 3. Eyes that underwent phacovitrectomy had a significantly lower gas fill on days 1–3 than eyes that did not.CONCLUSION:Postoperative pseudophakic status is associated with lower gas fill after MIVS. Adjusted gas fill should be considered in these cases.