Pressure Equalization Research Articles

Strong spherical V2O5/TiO2–SiO2 composites obtained by template combined with sol-gel method

This study is devoted to the preparation of strong spherical composites V2O5/TiO2–SiO2 by a combined template and sol-gel method. The composition, size and shape of the colloidal particles in butanol ash with tetrabutoxytitanium and tetraethoxysilane, as well as the physicochemical processes leading to the strengthening of the spherical agglomerates obtained using an anion exchanger with a gel structure, have been determined. Electrophoresis, small-angle X-ray scattering, and viscometry were used to demonstrate the presence in the sol of positively charged colloidal particles of lenticular and cylindrical shape, whose size, when the sol is stabilised, reaches 53 Å. The absorption of the sol by the anion exchanger in vanadium form is due to the equalisation of the osmotic pressure in the anion exchanger/sol system. Spherical composites with a diameter of 300 µm were obtained. It was shown by X-ray diffraction that the composites consist of V2O5 with an orthorhombic structure, TiO2 with an anatase structure, and amorphous silicon dioxide. The interaction at the interface between the phases of V2O5 with TiO2 and SiO2, which leads to the strengthening of the sphere of the V2O5/TiO2–SiO2 composite, has been demonstrated by IR and Raman spectroscopy. The results obtained can be used for the synthesis of MxOy/TiO2–SiO2 oxide composites with spherical agglomerates.

The start-up characteristics of a novel loop heat pipe with stainless steel capillary wick

Loop heat pipe (LHP) is an advanced thermal management technology that utilizes liquid–vapor phase change and capillary action to achieve efficient heat transfer across long distances and in various directions. The start-up of an LHP is crucial for its reliable and stable operation. This study aims to explore the start-up characteristics and temperature variations of various components under different heating conditions by designing a cost-effective flat plate evaporator LHP with a stainless-steel casing and acetone as the working fluid. The experimental analysis examined the performance of the LHP under varying heating powers from 28 to 60 W, positions, and gravity angles. The findings revealed that the LHP successfully started at 28 W, and a temperature overshoot occured when the heating position was near the compensation chamber. Notably, the start-up time was 400 s faster compared to the heating condition near the mean pressure chamber. When the evaporator was tilted such that the compensation chamber was above the evaporator’s pressure equalization chamber, circulation within the LHP could not be established. The thermal resistance of the LHP decreased with increasing heating power, achieving a maximum reduction of 51.51 %. When both the compensation chamber and the mean pressure chamber were heated simultaneously, the impact of the gravity inclination angle on thermal resistance was minimized. This study introduces an innovative capillary wick LHP with high start-up success rates and cost-effectiveness, providing both empirical data and theoretical insights for the refinement and optimization of civilian LHP designs.

High frequency venting of MEMS ultrasonic transducers and sensors: materials solutions.

Abstract This paper introduces the concept of ultrasonic venting. Similar to acoustic vents, ultrasonic vents refer to the aperture in air-coupled MEMS ultrasonic transducers (either PMUT or CMUT) intended to allow the equalization of internal and external pressures, the transfer of heat and the pass of ultrasonic waves, while impeding the penetration of fluids or particles that can affect the transducer membrane. To that end, vents are covered with a porous membrane whose properties are tuned to meet the afore mentioned requirements. The main difficulty in ultrasonic venting, compared with acoustic venting, is that the required “transparency” to ultrasonic waves is much more difficult to achieve. This involves two main problems as both transmission loss and frequency distortion are much larger at ultrasonic frequencies than in the audio range. The objectives of this paper are: to measure the response of acoustic venting materials in the ultrasonic frequency range, to determine the usability of these materials in ultrasonic vents, and to extract useful information for the design of efficient ultrasonic venting materials. Transmission coefficient spectra of different acoustic venting materials is measured in the frequency range 0.2 –2.7 MHz. The origin of the ultrasonic losses and frequency distortion are analysed as well as the role of mode conversion, internal interferences, modes interference, etc. Results reveal that none of the acoustic venting materials analysed can be used in ultrasonic venting applications, but the obtained knowledge about the response of these materials in the ultrasonic frequency range permit to advance in the selection of successful candidate materials for this application.

Exploring enhanced CO2 separation from blast furnace gas: A multicolumn vacuum swing adsorption approach with process design and experimental assessment

Excessive emissions of carbon dioxide (CO2) are a major driver of global warming. Blast furnace gas (BFG) represents a major source of CO2 emissions in the steel industry, accounting for approximately 30 % CO2 emissions among the industry sectors. Hence, effective CO2 capture from BFG is imperative. This study presents an approach utilizing the vacuum swing adsorption (VSA) technology to capture CO2 from BFG. A 6-column VSA rig was designed and constructed to separate CO2 from a simulated BFG (CO2/N2 = 20 %/80 %) using zeolite 13X as adsorbents. The VSA process involved steps of adsorption, desorption, heavy product purge, light product re-pressurization, and pressure equalization. Five different process modes, i.e., 1-column and 3-step, 2-column and 6-step, 2-column and 8-step, 3-column and 9-step, and 4-column and 16-step configurations, were implemented to evaluate the influence of various process design factors on the separation performance. Additionally, a 6-column and 36-step process was devised to conduct a parametric study of VSA cycles by varying the adsorption duration and desorption pressure. Results revealed the pivotal role of heavy product purge and pressure equalization on the separation performance. The six-column process achieved a CO2 purity and recovery of 94 % and 82 %, respectively, with a energy consumption of 0.76 GJ/tonCO2 when employing a desorption step duration of 240 s and pressure of 8 kPa. In addition, a method of process optimization based on the bed capacity ratio, C, was introduced in this study, which provides a dimensionless quantity of the utilization of the adsorption column. Moreover, capturing CO2 from BFG through the VSA cycle not only enhances its heating value but also yields substantial advantages in terms of mitigating CO2 emissions.

Enhancing coal seam gas pressure measurement accuracy and preventing leakage through dual chamber pressure balancing in borehole

Accurate measurement of coal seam gas pressure (CSGP) is critical to the evaluation of coal mine gas hazards and the potential of coal seam gas extraction. In this study, we investigate gas leakage from chambers and its influences on CSGP measurement results (MR) through numerical simulations. Furthermore, we propose, analyze and validate a novel method that balances gas pressure between two chambers, i.e. the measurement and regulation chambers, in a borehole. The results demonstrate that: (1) Traditional CSGP measurement method utilizing boreholes with a single chamber exhibit a gradual expansion of the gas pressure dropping region around the borehole, accompanied by an initial increase in chamber gas pressure followed by stabilization. The gas leakage process within the chamber undergoes three typical stages. (2) The increase of gas leakage lowers the MR value and raises the CSGP measurement error ratio (R). The relationship between MR, R and the stable value of gas leakage is nearly linear. (3) The proposed novel CSGP measurement method involves continuous gas injection into the regulation chamber to establish a dynamic gas pressure balance region between the two chambers. This approach minimizes gas leakage in the measurement chamber and accelerates gas pressure recovery. Maintaining dynamic pressure equality between the dual chambers is essential for minimizing R. (4) An automatic regulation unit is developed to achieve dynamic gas pressure balancing between the two chambers. With the novel method, R values remain below 3%, yielding higher CSGP measurement accuracy compared to alternative approaches.

Transport Characteristics and Potential Source Areas of PM2.5 in Yangquan City Under Different Pollution Levels

Based on the PM2.5 monitoring data, NCEP data, and the meteorological data of the weather situation analysis at the corresponding time in Yangquan City from 2020 to 2022, using the HYSPLIT4 backward trajectory model, multi-station potential source contribution factor analysis （MS-PSCF） and trajectory density analysis （TDA） were introduced to study the differentiation and classification of PM2.5 transport channels and potential sources in Yangquan City. The results showed that： ① The PM2.5 pollution in Yangquan was mainly concentrated in Yangquan and Pingding, whereas the pollution in Yuxian was relatively light. The proportion of days with different pollution levels and the average and maximum values of PM2.5 concentration in Yangquan and Pingding were significantly higher than those in Yuxian, and the distribution characteristics of PM2.5 were closely related to the local special terrain. ② The amount of PM2.5 pollution and the concentration of PM2.5 in different pollution levels were the highest in light wind weather. The influence of east-west regional transport on PM2.5 pollution times and PM2.5 concentration of Yangquan and Pingding was obvious, and the contribution of east wind was significant. The influence of local pollution sources was the main factor in the moderate pollution weather in Yuxian County. ③ There were four main ground conditions for the generation and maintenance of moderate or above pollution weather： warm low pressure type （22%）, high pressure front （bottom） type （54%）, high pressure back type （14%）, and pressure equalization field （10%）. High pressure front （bottom） type was the main ground situation causing the increase in PM2.5 concentration. There were two types of upper air conditions, namely, flat westerly flow type （78%） and northwest flow type （22%）. The upper westerly flow type was the main upper air condition that caused the increase in PM2.5 concentration. ④ The results of transport channels and potential source areas of PM2.5 with different pollution levels obtained by MS-PSCF and TDA were consistent. The main transport channels of PM2.5 were the northeast, southeast, and northwest channels, whereas the northeast and southeast channels were short-distance transport routes, which were the main routes causing the increase in PM2.5 concentration. The northwest channel was consistent with the northwest dust transport channel, belonging to long-distance transmission. The main potential source areas of PM2.5 pollution were located in the central and western parts of Hebei and the southeast part of Hebei, the northeast part of Henan and its junction with the southwest part of Shandong, and the southeast part of Shanxi.

Study on Safety Mining Technology of Gob in Stopping Face by Replacing Pressure Equalization with Gob Pumping—A Case Study of Sitai Mine

Gas control in the upper corner of the natural coal mining face with high gas is always a difficult problem that troubles the safe production of the working face. Among them, a high gas-prone natural coal mining face with ground air leakage is more likely to cause gas and CO to exceed limits in the corner of the working surface and is difficult to control. The traditional treatment methods often have some problems; for example, it is easy to increase air leakage in the gob with the method of gas extraction in the gob, which is not conducive to the prevention and control of spontaneous combustion of coal in the gob. At present, the more effective method is the pressure-equalization method. However, the pressure-equalization measures need to establish a complex pressure-equalization system, and close cooperation between the systems is required; once the system power fails or equipment failure occurs, the pressure-equalization state changes randomly, and it is easy to cause gas over-limits and other faults. Therefore, this paper presents a new method to control gas in the gob of a coal seam by pumping the gob of the upper-adjacent layer, using the negative pressure of pumping, and balancing the negative pressure of the upper-adjacent layer and the gob of the coal seam to form a new pressure-equalization relationship. This method can prevent the toxic and harmful gases in the goaf of the upper-adjacent layer from escaping into the passageway of the gob of the local coal seam, reduce the air leakage in the goaf, and benefit the gas control and spontaneous coal combustion prevention in the goaf.

Characteristics of numbering-up and flow distribution of multi-channel microreactor with 2-D constructal inlet distributors

In this work, the flow distributions of 16-, 8-, 4-, 2-channels microreactors with 2-D constructal inlet distributors were measured. The results showed an increase in channel numbers caused a decreasing uniformity of the flow distribution. Both asymmetrical velocity profiles before a bifurcation point and asymmetrical flow resistance after a bifurcation point played an important role on the flow distribution in microchannels. The uniformity of flow distribution showed a trend of firstly increasing and then remaining unchanged with the increase of Re (4 ∼ 680). The pressure drops of microreactors were also investigated and the empirical method is in the acceptable range for estimating the energy consumption. Extending the channel length after bifurcation point from 124.46 mm to 160.95 mm and incorporating a bypass pressure equalization chamber at bifurcation point could improve the uniformity of flow distribution.

Pressure Equalization Element for Electric Axles and Gearboxes

Pressure Equalization Element for Electric Axles and Gearboxes

Influence Factors of Pressure Swing Adsorption for Oxygen Production by the Orthogonal Method and the Response Surface Method

Adsorption pressure is one of the important factors affecting oxygen production in the process of pressure swing adsorption oxygen production. Three important factors, namely, the adsorption period, pressure equalisation time, and outlet flow rate, determine the variation in the adsorption pressure. In this study, the effects of the adsorption period, pressure equalisation time, and outlet flow rate on oxygen concentration were investigated through orthogonal experiments and response surface analysis. The experiments verified that three factors including the adsorption period, pressure equalisation time, and outlet flow rate have optimal values in the oxygen production process. Response surface analysis showed that the adsorption period had the greatest effect on the oxygen concentration, followed by the equalisation time, and the outlet flow rate had the least effect. The optimum process conditions are an adsorption time of 7.88 s, a pressure equalisation time of 0.9 s, an outlet flow rate of 2.31 L/min, and an oxygen concentration of 96.7%.

Comparative Efficacy of Different Therapeutic Interventions in Eustachian Tube Dysfunctions: A Cross-Sectional Analysis.

Eustachian tube dysfunction (ETD) affects a significant portion of the population, manifesting symptoms that impact the quality of life. Despite the prevalence of ETD, there remains a notable gap in comprehensive studies exploring the condition's dynamics within specific demographic contexts, particularly within Saudi Arabia. This study aimed to assess the prevalence and severity of ETD across different demographic groups, to evaluate the efficacy of various treatment modalities, and to identify key predictors of treatment response in a Saudi Arabian cohort. A cross-sectional study was conducted from June 2022 to May 2023 in tertiary care hospitals in the Aseer region, Saudi Arabia. Participants included adults diagnosed with ETD, assessed through clinical symptoms, otoscopic examinations, audiometric evaluations, tympanometry, and the ETDQ-7 questionnaire. The study incorporated advanced diagnostics such as nasopharyngoscopy and pressure equalization tube function tests and involved 154 participants, revealing significant variations in ETD severity, with the 46-60 age group exhibiting the highest mean ETDQ-7 score of 4.85, and urban residents displaying lower severity scores compared to rural counterparts. Pharmacological interventions were most effective, achieving the highest symptom relief and audiological improvement rates of 87.78%. Multivariate regression highlighted age, geographic location, and treatment modality as key predictors of treatment efficacy, with notable interaction effects between climate conditions and treatment types influencing outcomes. The findings underscore the heterogeneity in ETD presentation and the differential efficacy of treatment modalities.

Driving rain tightness and defects of prefabricated concrete sandwich walls with joints, windows and balconies

There have historically been, and still are, problems with water intrusion into new external walls of prefabricated concrete sandwich elements in Sweden to a varying extent. The aim of this study was to obtain documented knowledge and data on driving rain resistance, to provide a basis for improvements and calculations in a common kind of concrete sandwich system with façade components and sealing products. The study included inspections and air pressure difference measurement of façades in the field and driving rain resistance testing of experimental set-ups in a laboratory. Inspection showed that vertical joints between the concrete elements were often significantly too narrow and, at the same time, adhesion loosening of building mastic in these joints was common. TDV-tubes were often incorrectly placed or had a bad incline. Field measurements indicate no pressure equalization, which is also confirmed by lab measurements. Lab results indicated inward leakage at window-wall interface, even without wind pressure, through the TDV-tubes despite a sharp incline, in element joints with a new kind of application of pre-compressed joint sealing tape. The largest leakage flows were of 0.4% of the vertical water flow across a unit width of the façade at the given height.

A framework for design wind loads on air-permeable multilayer cladding systems

Air-permeable multilayer cladding (vinyl siding, roof pavers, discontinuous metal roofing, solar panels, etc.) are one of the most common types of building components in North America. Their defining aerodynamic feature is that they have an air cavity separating the component from the sheathing, studs, or interior layer. Due to air-permeability, external wind loads can transfer into the air cavity between the layers. Although these cladding systems have similar geometries in many ways, design loads are not generally available for such systems. This study aims to synthesize the available literature on the pressure equalization factor, which is the proportion of external load acting on the cladding and provide a framework for design wind loads on air-permeable multilayer cladding systems. To accomplish this, the many factors that affect the pressure equalization factor, such as the gap-to-cavity-depth ratio, panel size, and exposure are discussed. Then, the pressure equalization factors from multiple studies are combined to examine the effect of effective area on the pressure equalization factor. Finally, recommendations for implementing these guidelines into design standards are provided.

Effect of prolonged pressure equalization on final drifting during pressure wire studies

Pressure drifting is a troublesome error in invasive coronary function tests. This study aimed to evaluate the relationship between prolonged and short-time pressure equalizations in pressure drifting. Pressure drifting was defined as the pressure gradient between the mean pressure of the distal wire sensor (Pd) and aortic pressure (Pa) when the wire was withdrawn to the tip of the guiding catheter. Significant drifts 1 and 2 were defined as the absolute values of pressure gradients > 2 and > 3 mmHg, respectively. A logistic regression model was used to evaluate the associations between prolonged pressure equalization and each pressure drifting. The prolonged pressure equalization strategy was associated with a lower incidence of drift 1 than the short-time pressure equalization strategy (6.84% vs. 16.92%, p < 0.05). However, no statistical differences were found in the incidence of drift 2 between the prolonged and short-time pressure equalization strategies (4.27% vs. 7.69%, p = 0.34). In the multivariable regression model, only the prolonged pressure equalization strategy predicted a lower incidence of pressure drift 1. In conclusion, the prolonged pressure equalization strategy was associated with a lower incidence of significant pressure drifting with more stringent thresholds than the short-time pressure equalization strategy.

Cholesteatoma in the pediatric aerodigestive population

ObjectivesTo report the prevalence of cholesteatoma and related comorbidities in pediatric aerodigestive patients requiring tracheostomy or airway reconstruction procedures. To use study findings to inform clinical management of these complex patients. MethodsA repository of clinical data drawn from our institution's electronic medical records was queried to identify airway reconstruction (airway) and complex hospital control (control) patient cohorts. Retrospective chart review was then performed to investigate the occurrence of cholesteatoma and related pathologies in these patients, as well as clinical management. ResultsThe prevalence of cholesteatoma in airway and control patients was 6/374 (1.60 %) and 35/30,565 (0.11 %), respectively. The relative risk of cholesteatoma diagnosis in airway patients was 14.01 (95 % CI 6.06–32.14). Airway patients were more likely than control patients to have pressure equalization tube history (relative risk 3.25, 95 % CI 2.73–3.82). Age at cholesteatoma diagnosis and first surgical intervention was younger in airway compared to control patients (5.43 vs. 8.33, p = 0.0182, and 6.07 vs. 8.82, p = 0.0236). However, time from diagnosis to intervention and extent of surgery were similar between the groups. ConclusionThis is the first study to investigate the prevalence of cholesteatoma in the pediatric aerodigestive population. The relative risk of cholesteatoma diagnosis was found to be 14 times higher in patients with tracheostomy or airway reconstruction history. Underlying eustachian tube and palatal dysfunction are likely contributing factors to the elevated risk. Additionally, cholesteatoma in this population was diagnosed and required surgical intervention at a younger age, which may suggest a more aggressive disease course. Providers should maintain a high degree of suspicion for cholesteatoma in this complex population.

Design of the intensification method with the help of FracCADE software

The object of research in the work is the FracCADE software, with which it is possible to simulate the process of hydraulic fracturing and well field, on which the intensification method is designed. This hydraulic fracturing simulator was developed by Schlumberger Ltd. based on proven physical principles of hydraulic fracturing to optimize the treatment process and proven in practice. The system includes a range of hydraulic fracturing models, from 2D models to extensive 3D simulations with lateral communication. It includes a number of complementary modules for fracturing fluid and proppant optimization, injection scheduling, real-time monitoring, pressure equalization, production forecasting and economic evaluation. Some models allow simulating the geometry of the fracture, solving proppant concentration problems, and simulating possible shielding due to proppant covering the fracture or the dehydration process. Hydraulic fracturing remains one of the main engineering tools for increasing the productivity of wells. The effect is achieved due to: – creation of a conductive channel (fracture) through the damaged (contaminated) zone around the well, in order to penetrate beyond its boundaries; – spreading of the channel (fracture) in the formation to a considerable depth in order to further increase the productivity of the well; – creation of a channel (fracture), which would allow changing, influencing the fluid flow in the formation. In the latter case, fracturing really becomes an effective tool that allows to manage the operation of the reservoir (in particular, change its filtering characteristics) and implement long-term strategic development programs. The concept of hydraulic fracturing is quite simple. In general, for relatively simple geology, the physical foundations of fracturing theory are fairly well developed and tested. For the most part, the difficulties boil down to two problems: the real geological conditions and the complex multidisciplinary nature of the fracturing process itself. The process of designing fracturing in order to achieve a certain result is closely related to rock mechanics (which affects the geometric parameters of the fracture), fluid hydromechanics (in which the tasks of controlling the flow of the working fluid and placing the proppant in the fracture are solved) and chemistry, which determines the behavior of materials, which are used during hydraulic fracturing. Moreover, the hydraulic fracturing project must take into account the physical limitations imposed by the specifics of the real deposit and well. In addition, to achieve the desired results, the fracturing operation must be carried out in strict accordance with the calculations (that is, a complete cycle in which each operation plays its role).

Numerical analysis of pressure variation and gas load effects in the refrigeration system for household refrigerators

Insufficient air evacuation from a refrigeration system prior to refrigerant charging can lead to an increased non-condensable gas concentration, negatively impacting system performance. Despite its critical importance, literature on refrigeration system vacuuming procedures is notably lacking. This study developed numerical methods and constitutive models to assess gas load, validated against measured pressures using experimental setups. The model developed can be extended and applied to a wide range of vacuum systems. Examining the vacuuming process in a household refrigerator, a connected vacuum pump expedited the process, revealing higher pressures in the capillary tube and condenser outlet due to low flow conductance. The rate of pressure increase attributable to the gas load from outgassing and degassing remained below 0.6 %, deemed negligible during vacuum pump operation. A 24-hour simulation post-vacuum pump cessation showcased pressure equalization and subsequent rise due to outgassing and degassing, resulting in a 201 % increase in pressure within the compressor’s internal space connected to the process pipe. The pressure increase in the compressor attributable to outgassing amounted to 140 %, surpassing the 59 % from degassing. Notably, assuming a 3 μm crack in the process pipe led to a continuous increase in refrigerator system pressure over 24 h. Leakage significantly increases the amount of non-condensable gases inside the system, potentially leading to increased energy consumption and deterioration in system performance.

Speech, Language, Hearing, and Otopathology Results From the International Smith-Magenis Syndrome Patient Registry.

Smith-Magenis syndrome (SMS), a rare, genetically linked complex developmental disorder caused by a deletion or mutation within chromosome 17p11.2, is associated with delays in speech-language development, otopathology, and hearing loss, yet previous studies lack comprehensive descriptions of hearing and communication profiles. Here, analyses of patient registry data expand what is known about speech, language, hearing, and otopathology in SMS. International speech-language and hearing registry survey data for 82 individuals with SMS were analyzed using descriptive and inferential statistics. Hearing loss, history of otitis media and pressure equalization (PE) tubes, communication mode, expressive/receptive language, and vocal quality were analyzed for all subjects and subjects grouped by age. Statistical methods included descriptive statistics and Pearson's chi-square tests of independence to test for differences between age groups for each variable of interest. Association analyses included Pearson's correlations. Hearing and otological analyses revealed that 35% of subjects had hearing loss, 66% had a history of otitis media, and 62% had received PE tubes. Speech-language analyses revealed that 60% of subjects communicated using speech, 79% began speaking words at/after 24 months of age, 92% combined words at/after 36 months, and 41% used sign language before speech. There was a significant association between the age that first words were spoken and the age that PE tubes were first placed. Communication strengths noted in more than 40% of subjects included social interest, humor, and memory for people, past events, and/or facts. Significant delays and impairment in speech-language were common, but the majority of those with SMS communicated using speech by age 6 years. Age was a significant factor for some aspects of hearing loss and communication. Neither hearing loss nor otitis media exacerbated language impairment. These results confirm and extend previous findings about the nature of speech, language, hearing, and otopathology in those with SMS.

Analysis of Microphone Coupling and Zero-Point Calibration Model for Non-Resonant Photoacoustic Spectroscopy

Dissolved Gas Analysis (DGA) of transformer insulation oil is an effective method for monitoring transformer operating conditions and diagnosing faults. Photoacoustic spectroscopy (PAS) is widely employed for online dissolved gas analysis in transformer oil. The positioning of the pressure equalization hole within the sound field significantly impacts the microphone’s sensitivity when coupled with the photoacoustic cell in non-resonant photoacoustic spectroscopy. The static temperature and humidity characteristics inside the photoacoustic cell also have a notable influence on the microphone’s output signal. Consequently, an analysis is performed to explore the relationship between the sensitivity of the photoacoustic spectrometer and temperature/humidity, leading to the optimization of the system configuration based on the microphone parameters. Moreover, the photoacoustic zero-point signal is influenced by the temperature and humidity levels within the photoacoustic cell. To address this problem, air mixtures at different humilities are measured, resulting in the establishment of a zero-point model for the background signal in Photoacoustic Spectroscopy (PAS). Subsequently, the experimental detection of acetylene under various humidity mixtures is conducted, successfully extracting effective signals for the measurement of 5 ppm acetylene gas. These results serve as evidence showcasing the efficacy of both the proposed structural optimization and zero-point model put forth in this study.

Timing of First Set of Pressure Equalization Tubes in Pediatric Patients With Cleft Deformities.

Children with cleft palates often have comorbid eustachian tube dysfunction requiring pressure equalization tubes (PETs). PETs can relieve middle ear effusions that impede hearing. Ideal PET placement timing in this population is controversial. In this study, the audiologic exam passing rates of patients with cleft palate prior to and following PET insertion were assessed. Rates for patients receiving PETs at different ages were compared. It was hypothesized that earlier PET placement may benefit patients with additional months of improved hearing. A retrospective chart review was performed of patients with cleft palate between November 22, 2016 and November 22, 2021 at a tertiary center. Statistical analysis compared passing/normal audiologic exams in patients receiving PETs at different ages. A total of 348 patients had cleft palate diagnoses, received PETs, and had adequate hearing data for inclusion. Those with PETs inserted at 3 months of age or less had an increase in percent of patients passing audiologic exams following versus prior to PET insertion of 13% (1.3 times improvement). Those receiving PETs between 7- and 12-months had the largest rate of improvement (42%) (2.4 times improvement); other groups had changes in passing rates between 31% and 40%. The rate of passing audiologic exams following PET insertion was high across all groups, ranging from 66% to 81%. This is one of the first studies exploring the timing of PET placement in this population and showed that patients receiving PETs at 3 months of age or younger passed subsequent audiologic exams at similar rates relative to those receiving PETs later in life. 3 Laryngoscope, 134:3391-3394, 2024.