Leak Pressure Research Articles

Comprehensive Aerothermal Investigation of Turbine Blade Multicavity Squealer Tip Using a Novel Methodology With Uncertainty Quantification

Abstract Ascertaining the uncertainty in the aerothermal performance of blade tips is crucial, as it represents the most delicate component of modern gas turbines. In this research article, a novel and efficient approach is proposed for quantifying uncertainties in aerothermal performance using a combination of universal kriging, polynomial chaos expansions, and Smolyak sparse grid technology. This method was applied to investigate the aerothermal performance of a high-pressure gas turbine rotor blade tip with high-dimensional robustness. The outcomes of the uncertainty quantification calculation reveal that the downstream total pressure loss coefficient and leakage flowrate increase under normal-speed (subsonic) and high-speed (transonic) conditions. The key uncertainty input that affects the aerodynamic performance of normal-speed and high-speed squealer tip is inlet total pressure fluctuation, with a variance index on the leakage flowrate of normal-speed and high-speed squealer tip of up to 73.92 and 83.85%, respectively. The study suggests that it is more important to control the operating conditions fluctuation than the cavity depth machining accuracy for aerodynamic performance robustness, which applies to both normal-speed and high-speed squealer tips. In line with the aerodynamic performance, the heat flux of normal-speed and high-speed squealer tip increases during operation. Notably, the sensitivity of high-speed squealer tip aerodynamic performance to operating condition fluctuations increases compared to the normal-speed squealer tip, necessitating active intervention for fluctuations in operating conditions at a higher cost for the high-speed squealer tip. The sensitivity analysis results indicate that the inlet total temperature fluctuation is the key parameter that controls the normal-speed and high-speed squealer tip heat flux uncertainty. Finally, it is worth noting that while the use of ribs can effectively enhance the robustness of blade tip heat transfer performance, the heat flux near the root of the ribs fluctuates significantly, which may further increase the thermal fatigue tendency in this region during actual operation.

Prediction of Leakage Pressure in Fractured Carbonate Reservoirs Based on PSO-LSTM Neural Network

Shunbei Oilfield is a fractured carbonate reservoir with complex geological structures that are influenced by fault movements and prone to collapse and leak incidents. Precisely predicting leakage pressure is crucial for conducting fracturing operations in the later stages of production. However, current fracture-related leakage pressure prediction models mostly rely on statistical and mechanical methods, which require the consideration of factors such as fracture aperture and parameter selection, thereby leading to limitations in prediction efficiency and accuracy. To enhance the accuracy of reservoir leakage pressure prediction, this study leverages the advantages of artificial intelligence methods in dealing with complex nonlinear problems and proposes an optimized Long Short-Term Memory (LSTM) neural network prediction approach using the Particle Swarm Optimization (PSO) algorithm. Firstly, the Spearman correlation coefficient is used to evaluate the correlation between nine parameter features and leakage pressure. Subsequently, an LSTM network framework is constructed, and the PSO algorithm is applied to optimize its hyper-parameters, establishing an optimal model for leakage pressure prediction. Finally, the model’s performance is evaluated using the Coefficient of Determination (R2), Root Mean Squared Error (RMSE), and Mean Absolute Percentage Error (MAPE). The evaluation results demonstrate that the PSO-optimized LSTM model achieved an R2 of 0.828, RMSE of 0.049, and MAPE of 3.2, all of which outperformed the original model. The optimized LSTM model showed an average accuracy approximately 12.8% higher than that of the single LSTM model, indicating its higher prediction accuracy. The verification results from multiple development wells in this block further confirmed that the deep learning model established in this study surpassed traditional methods in prediction accuracy. Consequently, this approach is beneficial for drilling engineers and decision-makers to plan drilling operations more effectively and achieve accurate risk avoidance during the drilling process.

A Leakage Prediction Model for Sealing Performance Assessment of EPDM O-Rings under Irradiation Conditions.

In this work, a model for predicting the leakage rate was developed to investigate the effect of irradiation on the sealing performance of ethylene propylene diene monomer (EPDM) O-rings. The model is based on a mesoscopic interfacial gap flow simulation and accurately predicts the sealing performance of irradiated and non-irradiated materials by utilizing the gap height as an indicator in a mechanical simulation of the O-ring under operating conditions. A comparison with vacuum test results indicates that the model is a good predictor of leak initiation. The positive pressure leakage of the O-rings was investigated numerically. The results show the following. The sealing performance of the non-irradiated O-ring is much better than that of the irradiated one. The sealing performance is the worst at 0. 713 MGy and the best at 1.43 MGy, and the seal is maintained at an absorbed dose of 3.55 MGy. A theoretical analysis of the non-monotonic variation using the proposed model shows that the leakage behavior of the O-rings depends not only on the material properties but also on the roughness and prestressing properties. Finally, a method was proposed to classify the sealing performance, using the maximum allowable leakage rate as an indicator.

Experimental Test of Pressure Variation and Leakage Location in Petroleum Pipeline Leakage Process

Experimental Test of Pressure Variation and Leakage Location in Petroleum Pipeline Leakage Process

Microfluidic investigation on asphaltene interfaces attempts to carbon sequestration and leakage: Oil-CO2 phase interaction characteristics at ultrahigh temperature and pressure

CO2 huff-n-puff is a potential approach to improve the oil displacement efficiency in the deep reservoirs, which can achieve carbon sequestration and efficient oil production, simultaneously. However, the fundamental understanding of carbon mass transport, sequestration and leakage mechanism in deep geological reservoirs at the microscopic pore scale is still ambiguous. In this work, we innovatively designed a precise CO2 huff-n-puff microfluidic experiment under ultrahigh temperature and pressure conditions (55 MPa, 115 °C) to study the microscopic mechanism of CO2 utilization, storage and leakage (CUSL) in pore scale. Moreover, we proposed the quantitative analysis method for oil-CO2 interaction behavior to explicit dissolution and extraction characteristics, pressure threshold and interface stability by introducing Pseudo-Color algorithm and relevant parameters such as dynamic oil swelling factor, contact angle and gray value. Then, the pore-scale dynamics of the fluid interaction mechanism during the soak and puff process were quantitatively characterized, corresponding to the carbon sequestration efficiency of crude oil continuously exposed to scCO2 and the leakage risk with step-down production, respectively. The experimental results indicate that during the huff process, the oil-CO2 phase behavior characteristics at 115 °C can be divided into swelling, immiscible extraction and miscible extraction regions, which are coordinately controlled by dissolution mechanism, capillary effect and vaporization mechanism. Moreover, ultrahigh temperature oil generally requires higher pressure to start extraction and miscibility (Pext = 6.38 and 15.96 MPa, MMP = 9.71 and 23.73 MPa, T = 50 and 115 °C, respectively), while the asphaltene precipitation pressure Pasp is lower. At ultrahigh temperatures, the oil-CO2 interaction also enters the contact angle fluctuation region in advance, and the morphology of asphaltene particles is single, fine and uniform. When the soaking time is 36 min, the non-extractable oil component gradually evolves into a carbon sequestration interface. During the subsequent puff process, the more stable the carbon sequestration interface in the smaller blind end, the lower the leakage risk, corresponding to the leakage pressure difference of up to 40.93 MPa. This work has important practical significance for deep resource extraction and CUSL industrial application.

Numerical and experimental analyses of methane leakage in shield tunnel

Tunnels constructed in gas-bearing strata are affected by the potential leakage of harmful gases, such as methane gas. Based on the basic principles of computational fluid dynamics, a numerical analysis was performed to simulate the ventilation and diffusion of harmful gases in a shield tunnel, and the effect of ventilation airflow speed on the diffusion of harmful gases was evaluated. As the airflow speed increased from 1.8 to 5.4 m/s, the methane emission was diluted, and the methane accumulation was only observed in the area near the methane leakage channels. The influence of increased ventilation airflow velocity was dominant for the ventilation modes with two and four fans. In addition, laboratory tests on methane leakage through segment joints were performed. The results show that the leakage process can be divided into “rapid leakage” and “slight leakage”, depending on the leakage pressure and the state of joint deformation. Based on the numerical and experimental analysis results, a relationship between the safety level and the joint deformation is established, which can be used as guidelines for maintaining utility tunnels.

Study on numerical simulation of leakage and diffusion law of parallel buried gas pipelines in tunnels

Parallel buried gas pipelines in tunnels are located in a confined space environment, where natural gas is vulnerable to accumulating to the minimum explosion limit concentration after a leakage accident. Therefore, to reduce the time for locating the leakage source after an accident and compensate for the loss of emergency response, an experimental model for scaling parallel gas transmission pipelines in tunnels was established and the dispersion characteristics and influencing factors of continuous leakage of natural gas within buried soil and in tunnel space were investigated numerically, and the correlation between the volume of the explosion range of natural gas within the tunnel space and each influencing factor was explored using gray correlation analysis. The research shows that the leakage dispersion process of parallel buried gas pipelines in tunnels includes seepage leakage in the soil region and diffusion transport in the tunnel air region. In the soil region, natural gas from the pipeline leak forms a circular shape and tends to percolate upward due to the combined effect of pressure and concentration gradients.In the tunnel air region, the spatial dispersion of natural gas concentration obeys a multivariate Gaussian distribution, and the temporal dimension is divided into three phases: the initial phase of leakage, the spreading phase and the stable phase of leakage. The diffusion speed of natural gas is positively correlated with the operating pressure of pipeline. The concentration peak value (ymax) at the leakage orifice position and the leakage aperture (dx) approximately meet the linear relationship: ymax= 7.62dx. The diffusion path of natural gas is greatly influenced by the orientation of the pipeline perforations, and the tunnel walls have a directional effect on the diffusion of natural gas. The main factors affecting the volume of the explosion range of natural gas within the tunnel space are parallel pipeline leakage pressure, pipeline leakage aperture, parallel pipeline leakage position, pipeline operating pressure, and pipeline leakage direction, with grey correlation coefficients of 0.76, 0.675, 0.662, 0.553, and 0.55. The proposed model was demonstrated be able to simulate and predict the diffusion of natural gas under the accidental leakage of buried gas pipelines in tunnels. And the results of this study can guide the installation of buried gas pipelines crossing mountain tunnels to prevent accidents.

Dynamic Prediction of Performance Degradation Characteristics of Direct-Drive Electro-Hydraulic Servo Valves

Direct-drive electro-hydraulic servo valves are widely used in the aerospace industry, in the military, and in remote sensing control, but there is little research and discussion on their performance degradation and service life prediction. Based on previous research, erosion wear is the primary physical failure form of direct-drive electro-hydraulic servo valves, and parameters such as opening, oil contamination, and pressure difference are used as influencing factors of direct-drive electro-hydraulic servo valves. Pressure gain and leakage are used as performance degradation indicators of servo valves, and multiple types of sensors are used for data monitoring. Experimental benches are arranged and verified through experiments. Based on the data and laws obtained from the experiments, the exponential smoothing algorithm and the ARIMA model algorithm were used to establish a prediction model for the servo valve, and the dynamic prediction of the performance indexes was carried out. The error calculation and analysis of the prediction results and the experimental results were then carried out using the Copula function and other mathematical knowledge to verify the accuracy and applicability of this prediction model. This study provides theoretical support and practical guidance for applying and designing direct-drive electro-hydraulic servo valves in industrial applications such as aerospace, sensor experiments, and remote sensing control.

Pressure versus volume-controlled ventilation with BASKA mask airway in laparoscopic cholecystectomy: A randomized clinical study

ABSTRACT Background The best ventilation mode that suits with LMAs is still unclear. In this study, we investigated the ventilatory performance of Baska masks in patients who underwent elective laparoscopic cholecystectomy under general anaesthesia and pneumoperitoneum with either volume-controlled ventilation (VCV) or pressure-controlled ventilation (PCV) mode. Methods Fifty-Six patients with ASA I – II, who underwent laparoscopic cholecystectomy, were randomly classified into VCV (n = 28) and PCV (n = 28) groups. The lung was ventilated with a tidal volume of 8 ml/kg in the VCV group. It was ventilated initially using an inflating pressure that delivered a tidal volume of 8 ml/kg with a maximum of 35 cmH2O in the PCV group. The primary outcome was the intraoperative oropharyngeal leak pressure (OLP) of the Baska mask. Secondary outcomes were intraoperative lung mechanics, arterial carbon dioxide levels, and perioperative adverse effects. Results After pneumoperitoneum inflation, the OLP, peak inflation pressure (PIP), mean pressure (Pmean), PaCO2, and end-tidal CO2 significantly increased, and the calculated dynamic compliance significantly decreased in both ventilation modes. All variables partially returned to baseline after pneumoperitoneum deflation. Patients ventilated with PCV mode demonstrated significantly lower PIP and PaCO2 levels but higher dynamic compliance with statistically comparable OLP-PIP difference and higher leak fraction. Conclusion In this study, Patients ventilated with PCV mode showed lower PIP and PaCO2 but higher dynamic compliance, and higher leak fraction. However, both modes investigated provided effective Baska mask ventilation and maintained the OLP throughout the procedure with a statistically comparable OLP-PIP difference.

Reducing the urban environment impact of joint leakage of underground prefabricated structures: Waterproof performance improvement of WSR-EPDM gasket

Composite cross-section gaskets with ethylene propylene diene monomer (EPDM) and water swelling rubber (WSR) have been adopted for specific underground prefabricated structures to prevent water leakage. Research on the sealant behavior and waterproof failure mechanism of WSR-EPDM gaskets needs to be strengthened, and this paper presents a combined experimental and computational study to investigate the leakage behavior of WSR-EPDM gaskets. The mechanical performance of the WSR-EPDM gasket based on the 3-stages load-deformation relationship was detected using the electronic universal testing machine. And the waterproof performance of the WSR-EPDM gasket was tested based on the developed waterproof capacity test setup to monitor the water leakage pressure of joints under various combinations of joint openings and offsets. Three groups of mechanical tests and 12 groups of waterproof tests were carried out. Then, a series of finite element models were developed using the coupled Eulerian-Lagrangian method to reveal the failure mechanism of the WSR-EPDM gasket. The hyperelastic behavior of the WSR-EPDM gaskets was described using the two-coefficient Mooney-Rivlin hyperelastic model and verified against the gasket-in-groove mechanical test results. A supplementary parametric study investigated the effect of joint opening and offset. The correlation between gasket contact stress and supplied water pressure was analyzed. Finally, an improved gasket was developed, and the mechanical and waterproofing behavior was evaluated. The results indicated that the joint opening and offset negatively influenced the gasket waterproof behavior. The water-leakage path of the WSR-EPDM gasket was more likely to happen via the gasket-groove interface when the joint offset was larger. Furthermore, the mean contact pressure ratio to the water leakage pressure of 1:1 can be used as the criteria for a preliminary estimate of the potential water leakage path. The improved WSR-EPDM gasket showed excellent waterproof performance, with a maximum increasing ratio of 127.6%. The developed test setup and numerical methodology provide novel insights into the waterproof performance improvement of composite cross-section gaskets in complex situations.

Influence of three different closure techniques on leakage pressures and leakage location following partial cystectomies in normal dogs.

Transitional cell carcinoma (TCC) is the most common neoplasia affecting the canine urinary bladder. Partial cystectomy, when used adjuctively with medical management, has been shown to meaningfully extend medial survival time. Surgical stapling devices have a wide variety of uses and advantages over traditional closure methods and, to date, investigation into their use in canine partial cystectomies has not been documented. To determine the influence of three closure techniques on ex vivo leakage pressures and leakage location following canine partial cystectomy. Specimens were assigned to one of three closure techniques: simple continuous appositional closure with 3-0 suture, closure with a 60mm gastrointestinal stapler with a 3.5mm cartridge, and placement of a Cushing suture to augment the stapled closure, with each group containing 12 specimens. Mean initial leakage pressure (ILP), maximum leakage pressure (MLP), and leakage location at the time that ILP was recorded were compared between groups. Oversewn stapled constructs leaked at significantly higher ILP (28.5mmHg) than those in the sutured (17mmHg) or stapled (22.8mmHg) group, respectively. MLP was greater in the oversewn stapled construct group compared to other groups. Leakage was detected in 97% partial cystectomies, with leakage occurring from the needle holes in 100% of the sutured closure group, from the staple holes in 100% of the stapled only group, and from the incisional line in 83% and from bladder wall rupture in 8% of the augmented staple closure group. All closure methods withstood normal physiologic cystic pressures. Placement of a Cushing suture to augment stapled closures improved the ability of partial cystectomies to sustain higher intravesicular pressures compared with sutured or stapled bladder closures alone. Further in vivo studies are required to determine the clinical significance of these findings and the role of stapling equipment for partial cystectomy, as well as the clinical significance of suture penetration through the urinary bladder mucosa during closure.

Renal perfusion pressure and capillary leaks index as risk factors for acute kidney injury after major abdominal surgery

Background & Objective: Many factors can contribute to the development of acute kidney injury (AKI) following major abdominal surgery, including the effect of fluid extravasation into interstitial space due to capillary leakage. Microalbuminuria is also brought on by capillary leakage. Increased central venous pressure (CVP) or intra-abdominal pressure (IAP) will decrease renal filtration according to the degree of pressure transmission to the glomeruli. The objective of this study was to know the correlation of capillary leakage index (CLI), microalbuminuria [urine albumin to creatinine ratio (ACR)] and renal perfusion pressure (RPP) with the incidence of AKI. Methodology: A prospective longitudinal cohort design with consecutive sampling was used in this study. The parameters capillary leakage index (CLI), microalbuminuria (ACR) and renal perfusion pressure (RPP) were examined preoperatively, and at 12 h and 36 h postoperatively, and the incidence of AKI was observed till the fourth postoperative day. CLI was defined as C-reactive protein (CRP mg/dL) over albumin (g/L) multiplied by 100. RPP as glomerular pressure was obtained from mean arterial pressure (MAP), IAP, and renal venous pressure estimated by CVP, by the formula RPP = MAP-(IAP+CVP). Results: Following major abdominal surgery, 19 (25.68%) of the 74 subjects developed AKI. There was no significant difference in CLI and ACR between patients with and without AKI. Renal perfusion measurements examined at 0, 12, and 36 h showed significantly lower values in AKI patients. The relative risk (RR) of RPP was 9.125 with a 95 % CI of 1.141293−72.95725 (P = 0.037) after data analysis with Cox Regression to establish the correlation between CLI, ACR, and RPP, as well as covariate variables on the occurrence of AKI at 0 h. Compared to participants without AKI, those with AKI had a mortality risk of 2.384 times higher (P = 0.0351, 95 % CI = 1.133−5.018). Conclusion: Renal perfusion pressure showed a significant correlation with acute kidney injury. Additionally, there is a strong connection between acute kidney injury and mortality. Abbreviations: ACR- albumin to creatinine ratio; AKI- acute kidney injury; CLI- capillary leakage index; CVP- central venous pressure; IAP- intra-abdominal pressure; MAP- mean arterial pressure; RPP- renal perfusion pressure Key word: AKI; Capillary Leaks Index; Microalbuminuria; Renal perfusion pressure; Major abdominal surgery; Systemic capillary leak syndrome Citation: Suria Mariati NMA, Aditianingsih D, Marsaban AHM. Renal perfusion pressure and capillary leaks index as risk factors for acute kidney injury after major abdominal surgery. Anaesth. pain intensive care 2023;27(3):294−300. DOI: 10.35975/apic.v27i3.1925 Received: July 03, 2022; Reviewed: July 17, 2023; Accepted: April 22, 2023

Numerical modelling of the discharge behaviour of particles from a gas vessel

Particle-laden gas flows occur in a wide variety of process technologies. It is therefore a common safety scenario to understand how many particles will escape in the event of a leak or emergency pressure relief. Therefore, a vessel filled with gas and homogeneously dispersed solid particles was considered. The aim was to derive a model to describe the discharge of arbitrary spherical particles. For this purpose, multiple numerical simulations were performed with ANSYS CFX©. A cylindrical vessel with a volume of 2 m³, a 25 mm opening and a length to diameter ratio of 2 was considered. The system was considered adiabatic, isentropic, compressible, and subcritical with an ideal gas. The velocity field was described with a one-way Euler-Lagrange method. The particle density, particle size, the gas in the vessel, as well as the initial temperature and pressure in the vessel were varied. Based on a dimensional analysis a model was developed to estimate the discharged mass of particles. This model achieves a small mean absolute deviation from the simulation data of −0.03%. The prediction model is thus able to correctly represent all variables varied without having to carry out single complex numerical simulations. The model is the first model to derive the discharge behaviour of particles from pressure vessels.

Locating leakage in pipelines based on the adjoint equation of inversion modeling

This paper presents an adjoint method for locating potential leakage in a single-phase fluid pipeline based on the analytic solution of inversion modeling. By studying the mechanism of pipeline leakage pressure, the adjoint equation based on the governing equation of transient flow is established in the single-liquid phase aspect using inverse adjoint theory and sensitivity analysis method. The inverse transient adjoint equation is primarily derived from the single linear fluid pipeline in the semi-infinite domain. The Laplace method is then used to obtain an analytical solution that determines the location of pipeline leakage. The experimental results indicate that the analytic solution can quickly and accurately judge the leakage location of the pipeline. Furthermore, it presents a new approach to engineering applications, such as gas-liquid two-phase flow complex pipe networks, etc.

Comparison of Blockbuster LMA with Air Q LMA for Success of Blind Tracheal Intubation in Patients Undergoing General Anesthesia

Background: Blockbuster Laryngeal mask airway (LMA) is a device gaining popularity in airway management, and advantageous in ventilation and intubation. Air Q LMA is a supraglottic airway device with a shorter and wider breathing tube designed for ventilation as well as intubation in difficult airway. We aimed to evaluate the success of tracheal intubation using these devices. Methods: Overall 80 participants aged 18-60 years with ASA I and II were randomized into Group A (Air Q LMA) and Group B (Blockbuster LMA) using computer generated random numbers. The objectives of our study were to evaluate first pass successful intubation, ease, time and attempts taken for device insertion, oropharyngeal leak pressure, time for LMA removal and post operative complications. Association between variables were assessed with chi square test and unpaired t test. Result: There was a statistically significant difference in the first pass successful intubation between the groups which was higher in Group B (90%) than Group A (60%) (P<0.001), the overall successful intubation was more in Group B 97.5% compared to Group A 85%. The device insertion was easy in 85% patients in Group A and 95% patients in Group B. The time taken for introduction of Air Q was longer (38.15±4.92sec) when compared with blockbuster LMA (26.25±4.44sec), (P<0.001). Mean Oropharyngeal leak pressure of blockbuster LMA (32.40±3.99cmH2O) was greater than Air Q LMA (29.10±2.61cmH2O), (P<0.001). Conclusion: Blockbuster LMA provides greater success of blind tracheal intubation when compared to air Q LMA.

Research on the field strength characteristics and the flammable area of refrigerants leakage into a confined space

Some target refrigerants used in refrigeration systems have various flammability. Once the flammable refrigerants leak into a confined space, it is easy to pose safety hazards. Moreover, the leakage refrigerants undergo continuous expansion and compression processes in the near field of the confined space, and the field strength of the refrigerants changes dramatically, which has an impact on the diffusion and the concentration distribution of the refrigerant in the far field of the confined space. The differences in the field strength and the flammable area for different refrigerants are largely determined by the thermophysical parameters of the refrigerants. Therefore, to better assess the hazards of refrigerant leakage, R717, R290, R161, R32, R152a and R1234yf were selected as the targeted leakage refrigerants in this paper, R744 and R134a were selected as the referenced refrigerants, the temperature, velocity and concentration fields of the refrigerants leaking into a confined space were studied, the influence of thermophysical parameters on the field strength of the refrigerants in the near field was further analyzed, and the flammable area formed in the space was explored. The results found that the temperature field was mainly affected by the density and the specific heat of the refrigerant. The velocity field was mainly affected by the density and viscosity of the refrigerant. The concentration field was mainly influenced by the density, viscosity and diffusion coefficient of the refrigerant. When the density was close, Schmidt number could be used to assess the influence of the viscosity and the diffusion coefficient on the concentration field. Under the same leakage pressure, the range of the flammable area formed by the leakage of R290 was the largest, followed by R161 and R152a, the flammable areas of R1234yf and R717 were very close, and the flammable area formed by R32 was the smallest.

Robotic Intracellular Pressure Measurement Using Micropipette Electrode.

Intracellular pressure, a key physical parameter of the intracellular environment, has been found to regulate multiple cell physiological activities and impact cell micromanipulation results. The intracellular pressure may reveal the mechanism of these cells' physiological activities or improve the micro-manipulation accuracy for cells. The involvement of specialized and expensive devices and the significant damage to cell viability that the current intracellular pressure measurement methods cause significantly limit their wide applications. This paper proposes a robotic intracellular pressure measurement method using a traditional micropipette electrode system setup. First, the measured resistance of the micropipette inside the culture medium is modeled to analyze its variation trend when the pressure inside the micropipette increases. Then, the concentration of KCl solution filled inside the micropipette electrode that is suitable for intracellular pressure measurement is determined according to the tested electrode resistance-pressure relationship; 1 mol/L KCl solution is our final choice. Further, the measurement resistance of the micropipette electrode inside the cell is modeled to measure the intracellular pressure through the difference in key pressure before and after the release of the intracellular pressure. Based on the above work, a robotic measurement procedure of the intracellular pressure is established based on a traditional micropipette electrode system. The experimental results on porcine oocytes demonstrate that the proposed method can operate on cells at an average speed of 20~40 cells/day with measurement efficiency comparable to the related work. The average repeated error of the relationship between the measured electrode resistance and the pressure inside the micropipette electrode is less than 5%, and no observable intracellular pressure leakage was found during the measurement process, both guaranteeing the measurement accuracy of intracellular pressure. The measured results of the porcine oocytes are in accordance with those reported in related work. Moreover, a 90% survival rate of operated oocytes was obtained after measurement, proving limited damage to cell viability. Our method does not rely on expensive instruments and is conducive to promotion in daily laboratories.

Evaluation of Ambu-Aura-i laryngeal mask as a conduit for endotracheal intubation. A comparison with Air-Q intubating laryngeal airway in adult surgical patients

ABSTRACT Background Supraglottic airway devices (SGA) are used as primary devices or conduits for endotracheal intubation with normal or difficult airway. The purpose of this study was to assess how the Ambu-Aura-i laryngeal mask would act as a conduit for endotracheal intubation compared to the Air-Q Intubating Laryngeal airway in adult patients in operating room. Methods Fifty-four adult patients scheduled for elective procedures under general anaesthesia were divided into air-Q and Aura-i groups. The ease and time of insertion, the number of insertion attempts, the airway leak pressure, the duration of fiberoptic endotracheal intubation, the grade of the fibre-optic laryngoscopic view, and the time to remove the device were noted. Results Comparing the Aura-i group to the Air-Q group, the Aura-i group had a considerably shorter insertion time and a longer time to remove the device (28.1 ± 3.5 vs 32.7 ± 6.9 sec P-value = 00.4 and 40.7 ± 5.1 vs 32.0 ± 5.4 sec, P-value = 0.001; respectively). Both devices were comparable regarding the number of insertion attempts and the time to insert an endotracheal tube. Compared to the Air-Q group, the Aura-i group’s airway leak pressure was considerably greater (25.9 ± 3.9 vs 23.4 ± 4 CmH2O, respectively, P-value = 0.03). Both groups had comparable fibre-optic laryngoscopic view grades. Conclusion The Ambu-Aura-i laryngeal mask and the Air-Q intubating laryngeal airway are efficient conduits for fibre-optic endotracheal intubation in adults with Ambu-Aura-i Laryngeal mask exhibiting advantages in terms of device insertion time and use during mechanical ventilation.

Evaluating Performance of Circular Staplers Using Comparative Test Methods for Evidence-Based Surgery.

Circular stapler anastomosis is a common surgical procedure. Despite technological advancements, anastomotic leak remains a postoperative concern. Assessment of new technologies is impeded by variations in test methods and analysis, precluding outcome reproducibility and direct comparisons of results across studies. The development of robust and reproducible preclinical test methods is critical to accelerating stapling technology advancements. Leak pressure, staple line perfusion and security, and device removal force were quantified for triple-row (Tri-staple EEA, TriEEA) and double-row staplers (Echelon Circular Powered, ECP). Leak and perfusion testing were performed in vivo. Device removal force and staple line security testing were performed with synthetic medium using an Instron. Data were analyzed using unpaired student's t-test or Kruskal-Wallis test, with statistical significance defined as P < .05. Leak pressure was 73% higher in TriEEA vs ECP (P = .016). TriEEA staple line failure force was lower than ECP at 40 and 50mmHg (P = .001 and P = .023, respectively). Perfusion to the staple line was higher (148%) for TriEEA than for ECP (P = .003) and the force required to remove the device from its stapled anastomosis was 78% lower for TriEEA than for ECP (P < .001). This report addresses a primary limitation in stapling research by presenting novel methodologies which enhance clinical relevance and provide sufficient detail for reproduction by independent investigators. These methods are applied to a comparison between triple-row and double-row staplers to demonstrate utility of new test methods in assessing key technology design features.

Numerical Estimation of Gas Release and Dispersion from a Submarine Pipeline

Submarine pipeline gas releases and dispersions can cause safety concerns such as fire and explosion, which can cause serious casualties and property losses. There are many existing studies on the impacts of the horizontal diffusion distances of natural gas leakages from subsea pipelines, but there is a lack of research on the impact of influencing factors on vertical diffusion distances. Therefore, a diffusion model of natural gas leakage from a submarine pipeline is established by using the computational fluid dynamics method (CFD). The influence law and degrees of factors such as water depth at the leakage point, leak orifice size, leak pressure and the ocean current’s velocity on the leakages and vertical diffusion distances of natural gases from submarine pipelines are systematically investigated. The results show that the leaked natural gas jet enters the sea water to form an air mass, which rises continuously under the action of the pressure in the pipe and the buoyancy of the sea water. The gas mass breaks into smaller bubbles affected by the interaction between the gas–liquid two phases and continues to float up and diffuse to the overflow surface. It is also found that the ocean current’s velocity will affect the offset of leakage gas along the current direction; the depth of the leakage water, the pressure in the pipe and the leakage aperture will affect the time when the gas reaches the sea surface and the release area after a submarine pipeline’s leakage. The research results would help to support risk assessments and response planning of potential subsea gas release accidents.