Decrease In Gas Volume Research Articles

ILM Insertion for the Treatment of Macular Hole Associated with Phakic Intraocular Lens Implantation

Purpose: To report a case of macular hole closure using an internal limiting membrane (ILM) flap following implantation of a posterior chamber phakic implantable contact lens (ICL).Case summary: An 18-year-old female patient presented with visual loss of the left eye after ICL implantation. She had high myopia of -12.5 diopter (spherical equivalent) and a corrected visual acuity of 2/100. The fundus photograph and optical coherence tomography showed a full-thickness macular hole measuring 688 µm in width and 976 µm in length. The ILM around the hole was detached from the retinal surface, which was greater in size than the macular hole. The initial surgical intervention involved vitrectomy, inverted ILM flap placement, and gas tamponade. The decrease in gas volume was associated with a loss of the ILM flap. For hole closure, the remaining ILM flap in the peripheral macula was harvested and inserted in the hole during the second surgery. The silicone oil was used for tamponade. One month after ILM insertion, complete closure of the hole was observed. The visual acuity improved to 20/40 after silicone oil removal.Conclusions: A large full-thickness macular hole developed after ICL implantation in a patient with high myopia. Macular hole surgery using ILM insertion and prolonged tamponade closed the hole and effectively improved the visual acuity.

Coupling relationship of fluidization behavior, reaction and particle structure of Ni/MgO catalyst toward fluidized CO methanation

The coupling relationship of fluidization behavior, reaction activity and particle structure of Ni/MgO catalyst toward fluidized CO methanation is systematically investigated. The poor fluidization quality or defluidization, to a large extent, is caused by the rapid decrease in gas volume induced by methanation reaction. This reaction derived defluidization or poor fluidization results in great changes in structure and chemical compositions of the Ni/MgO catalyst, and which in turn lead to a decrease of reaction activity. The better fluidization quality catalyst is beneficial for maintaining the catalyst structure and exhibits the higher resistance to the negative effect by rapid decrease of the gas volume. The fluidization quality of the stable fluidized catalyst can be improved by addition of N2. However, the catalyst particles with poor fluidization quality are easy to be defluidized due to the rapidly decrease in gas volume even with addition of inert components.

Pressure Fluctuation Analysis of the Defluidization Caused by a Reaction Involving Gas-Volume Reduction in a Fluidized Catalyst Bed

Severe defluidization occurs when a reaction that is accompanied by a decrease in gas volume is performed in a fluidized catalyst bed. Defluidization occurs because the gas velocity in the emulsion phase decreases to less than the minimum fluidization velocity. Because numerous useful industrial reactions involve a decrease in gas volume, the development of a method for rapid detection of defluidization is important for maintaining good fluidization. In this study, the inside of a column was visually observed during CO2 hydrogenation in a fluidized bed. When the reaction rate was low, good fluidization was always observed. However, defluidization, such as channeling, occurred occasionally when the reaction rate was increased. These reaction conditions were classified as the defluidization region in this study. The time-change characteristics for the frequency of pressure drop fluctuations were studied using continuous wavelet transfer (CWT). Additionally, the autocorrelation function was used to determine the dominant frequency. Using these functions, the decrease in the dominant frequency and the periodicity of the pressure fluctuations were detected in the defluidization region, even when the bed was observed to be satisfactorily fluidized. On the other hand, the prediction of defluidization itself several seconds before it occurred proved difficult.

Prevention of defluidization by gas dilution for reactions involving gas–volume reduction

In industrial fluidized bed processes, the system often involved a change in volumetric flow. Defluidization occurs when reactions involving a decrease in gas volume are carried out in a fluidized catalyst bed. This is due to decrease in gas velocity below the minimum fluidization velocity in the emulsion phase. One method to improve fluidization quality is to supply an inert gas with reactant gases: similar effect can be obtained by supplying an excessive amount of one of the reactants. In the present study, the effect of a diluted reactant gas on fluidization quality is quantitatively analyzed by performing CO2 hydrogenation in a fluidized catalyst bed. Stable operation can be established by operating the fluidized bed to avoid the conditions contained in the defluidization zone using two parameters that influence fluidization quality.

Analysis of fluidization quality of a fluidized bed with staged gas feed for reactions involving gas‐volume reduction

AbstractA significant defluidization occurs when carrying out reactions involving a decrease in gas volume in a fluidized catalyst bed. The cause of this phenomenon is a decrease in the gas velocity in the emulsion phase below the minimum fluidization velocity. Fluidization quality is improved by a staged gas feed when hydrogenation of CO2 is carried out. To evaluate the experimental results, two parameters are introduced; gas‐volume reduction rate and gas‐volume ratio. Fluidization quality and defluidization zone are indicated as a map using these parameters. The vertical distributions of these parameters are calculated using a reactor model to obtain operating lines. The calculation shows that fluidization quality can be improved by operating the reactor by avoiding the operating lines of the defluidization zone in the map. For this purpose, it is required to control the gas‐volume ratio at a level near unity and maintain the gas‐volume reduction rate below 0.01/s. © 2010 American Institute of Chemical Engineers AIChE J, 2010

Elimination of Defluidization Caused by Reactions Involving a Volume Reduction in a Fluidized Catalyst Bed and Improvement of Fluidization by Two-Stage Feeding

Defluidization and a decline in fluidization quality were observed in reactions involving a decrease in gas volume. This was due to a reduction in gas velocity in the emulsion phase owing to the reactions. The decrease in the gas velocity led to a reduction in the emulsion phase voidage. Finally, a part of the fluidized bed was defluidized and lifted up through the column like a moving piston. In the present study, methanation of carbon dioxide was carried out as a model reaction, and the effect of the two-stage distribution of the fluidizing gas on the improvement of the fluidization quality was investigated. The bed was fluidized by supplying hydrogen from the bottom of the fluidized bed. The other reactant, carbon dioxide, was supplied from the bottom distributor and a secondary gas inlet. By using this method, it was possible to avoid defluidization. The influences of the level of the secondary inlet and the distribution ratio of carbon dioxide on fluidization quality were studied by plotting two parameters that affect fluidization quality.

Oleic acid lung injury: a morphometric analysis using computed tomography.

The oleic acid-induced lung injury (OAI) model is considered to represent the early phase of acute respiratory distress syndrome (ARDS). Its inherent properties are important for the design and the interpretation of interventional studies. The aim of this study was to describe the evolution of morphometric lung changes during OAI using computed tomography (CT) analysis. Furthermore, the effect of a temporary change in positive end-expiratory pressure (PEEP) was evaluated. Fifteen anaesthetized pigs were ventilated in volume-controlled mode with a baseline PEEP of 5 cm H(2)O. Helical CT scans were taken at baseline and 1 h after oleic acid injection. The PEEP was then either increased to 10 cm H(2)O (n = 5), decreased to 0 cm H(2)O (n = 5) or kept constant (n = 5) for 30 min. For the next 30 min, the baseline PEEP level was applied in all animals before the final CT scans 2 h after the induction of OAI. Dimensional and volumetric changes were determined from radiographical attenuation values. There was a major decrease in gas volume and an increase in tissue volume within the first hour. A net increase in total lung volume, with a larger transverse area but no displacement of the diaphragm, was manifest after 2 h. A minor increase in volume of non-aerated lung, located to the caudal region, was observed during the second hour. The tidal volume was redistributed to the middle and apical regions. The temporary change in PEEP did not influence the morphological progress of OAI. Decreased gas volume and increased tissue volume are the dominating morphometric characteristics of oleic acid lung injury, occurring mainly within the first hour. With these changes manifest, the course of injury is not affected by a limited period of moderately changed PEEP during the second hour. The net increase of total lung volume suggests a predominance of oedema formation over airway and alveolar collapse.

Anaerobic treatment of tannery wastewater: toxic effects of wastewater constituents and dosage of ferric chloride

Investigates anaerobic two‐stage treatment of tannery wastewater. This results in a mean chemical oxygen demand (COD) removal of 60 per cent for tannery B and more than 70 per cent for tanneries A and C with CODo = 5,710mg l‐1 and mean detention time held at 3.5 days. Gas production was small, rating an estimated 75 l kg‐1 CODo with CODo = 5,710mg l‐1. Tests simultaneously the influence of quality and quantity of wastewater on COD removal and gas production (multiple regression). Finds significant inhibitory effects were caused by chloride on gas volume and by sulphate on COD removal. Chromium showed no significant effect. Dosage of ferric chloride for removal of the toxic sulphide effected a decrease in gas volume and had no effect on COD removal (analysis of variance).

Methanation of carbon dioxide and fluidization quality in a fluid bed reactor—the influence of a decrease in gas volume

A large decrease of fluidization quality was observed when methanation of carbon dioxide was carried out in a fluid-bed reactor even if the catalyst particles had the optimal properties for good fluidization. The cause of this phenomenon was explored by measuring pressure fluctuations, bubble frequency and extent of CO 2 conversions. The results indicated that the decrease of the fluidity was caused by a reduction in volume of reactant gases due to the reaction. The voidage in the emulsion phase is considered to be an important factor affecting the fluidity. The fluidization quality and contacting efficiency could be improved by such devices as baffle internals or two-stage spargers.