Leakage Rate Research Articles

Percutaneous functional spinal unit cementoplasty versus percutaneous kyphoplasty for severe osteoporotic vertebral compression fracture complicated with endplate-disc complex injury: A retrospective case-control study.

Severe osteoporotic vertebral compression fracture (SOVCF) is frequently complicated by endplatedisc complex (EDC) injury. While percutaneous kyphoplasty (PKP) can offer rapid analgesia and facilitate early activity, it does not restore vertebral height and may result in intervertebral leakage and untreated EDC injury. This study aimed to evaluate the clinical outcomes of percutaneous functional spinal unit cementoplasty (PFSUP) for SOVCF complicated by EDC injury and compare its clinical and imaging outcomes with PKP. This was a retrospective case-control study. Patients with SOVCF complicated with EDC injury between January 1, 2018, and December 31, 2019, were recruited and assigned to the PKP group and PFSUP group based on their treatment procedures Back pain was evaluated using the visual analog scale (VAS) and daily life activities were assessed using the Oswestry disability index (ODI). X-rays were employed to observe the presence and location of cement leakage, as well as to measure the sagittal vertical axis (SVA) and local kyphosis angle (LKA). Loss of correction was calculated by subtracting the LKA after surgery from that at the final follow-up visit Subsequent vertebral fracture (SVF) was confirmed using the Genant semi-quantitative method and/or MRI. A total of 64 patients were included in this study. Among them 41 cases were assigned to the PKP group (28 females, 74.8 years on average), while the remaining 23 cases were assigned to the PFSUP group (15 females, 76.3 years on average). All surgical interventions were successfully completed without major complications. Compared to the PKP group, the PFSUP group had longer operation time (70.28 ± 11.44 vs 44.5 ± 10.12, P< 0.001) higher frequencies of radiation exposure (97.6 ± 19.85 vs 38.6 ± 9.53, P< 0.001), and a lower cement leakage rate (26.1% vs. 41.5%, P< 0.001). One day after surgery and at the final follow-up the PFSUP group had lower VAS and ODI scores, as well as lower LKA and Sva values compared with the PKP group (all P< .001). At the final follow-up visit, the PFSUP group demonstrated a lower loss of correction (4.38 ± 2.71 vs. 10.19 ± 3.41 P< 0.001) and a lower SVF rate compared to the PKP group (21.7% vs. 31.7%, P< 0.001). PFSUP outperformed PKP in alleviating pain restoring and maintaining sagittal balance, and lowering the incidence of cement leakage and SVF for SOVCF with EDC injury However, PFSUP was associated with longer operation time and high radiation exposure frequencies.

Experimental Study on Coal Oxidation and Temperature Rise Under Reciprocating Air Leakage

ABSTRACT Reciprocating air leakage often occurs in the goaf of coal mines because of changes in internal or external pressure. However, its impact on the spontaneous combustion of coal in the goaf is uncertain. Therefore, a comparative study of constant air leakage and reciprocating air leakage was carried out using a self-built system. The results indicate that reciprocating air leakage promotes coal oxidation and produces higher CO levels compared to constant air leakage. Further investigation was carried out to examine the effect of air leakage rate and reciprocating half-cycle (referred to as half-cycle hereafter) on coal oxidation and temperature rise. The results show that there is a linear relationship between resistance and air leakage rate in the coal oxidation heating space; however, the half-cycle length has little effect on resistance. The influence of a fixed air leakage rate on temperature and CO concentration does not always increase, with the maximum value achieved at 1.2 m3/h. Shorter half-cycles result in higher temperatures and CO concentrations. Gradually increasing air leakage rates and shortening half-cycles can promote coal oxidation and temperature rise and lead to higher CO production compared to previous scenarios. Additionally, the effect of using four different air leakage rates or half-cycle lengths is greater than that of using two. These research findings offer a theoretical foundation for preventing and controlling coal spontaneous combustion in goafs under complex air leakage conditions.

FP7.13 - Is There A Difference In Anastomotic Leak Rates Requiring Re-Operation Following Emergency Right Hemicolectomy Between Colorectal And Non-Colorectal Surgeons?

Abstract Aim Right sided colonic cancers can often obstruct and present as an emergency. The decision to perform an anastomosis following the right hemicolectomy resection is often multifactorial. This study explores whether there are differences in leak rates between colorectal and non-colorectal surgeons in the context of emergency right hemicolectomy operations performed for malignancy. Methods A retrospective study was conducted at a 3-site Trust in South-East England between 2017 and 2022. Theatre and Infoflex Cancer records were used to obtain patients who had undergone an open right hemicolectomy for malignancy and their operating surgeon. Discharge summaries and clinic letters were then used to ascertain return to theatre for an anastomotic leak. Results There were 281 patients who had undergone an emergency right hemicolectomy in this time interval. There was a 152:129 female:male ratio. 17 out of 37 patients had an anastomosis undertaken by an Upper Gastrointestinal Surgeon. 2 out of the 17 (12%) had an anastomotic leak. 129 out of 244 had an anastomosis undertaken by a Colorectal Surgeon. 17 of the 129 (13%) had an anastomotic leak. There was no significant difference between the leak rates between colorectal and non-colorectal surgeons (p=0.888). Conclusion The study shows that there is no statistical difference in right hemicolectomy anastomotic leak rates between colorectal and non-colorectal surgeons in the emergency setting.

EP39 - Retrospective study of delays in reversal of loop ileostomy – reasons and outcomes during the COVID era

Abstract Aims Formation of loop ileostomy is common after anterior resection to reduce the sequele of an anastomosis leak.1-5 Delays to reversal of ileostomy is associated with complications. Methods Retrospective study between 1 July 2017 – 30 June 2023. Patients were included: &amp;gt;18 years old, loop ileostomy formed as part of anterior resection surgery (benign and malignant). Exclusion criteria: loop ileostomy performed during other colonic resections, patients with inflammatory bowel disease, defunctioning ileostomy for obstructions. Primary outcome measures included complications associated with delayed closure of loop ileostomy and readmissions after reversal surgery. Secondary measures included reasons for delay to surgery, complications prior to reversal surgery, and morbidity and mortality associated with it. Results 135 patients were included. 85.9% of patients experienced delays in reversal surgery. Those without delays in surgery had higher rate of stoma-related complications (p=0.002). Delays were due to a long waitlist (p&amp;lt;0.01) and adjuvant chemotherapy (p=0.598). There was no significant differences in the delays to surgery during COVID pandemic. Delays were associated with higher rate of wound infection (6.04%), post-operative ileus (12.07%), anastomotic leak (1.72%), and Clostridium difficile (C.diff) infection (3.45%). Handsewn end to end anastomosis was associated with a higher proportion of post-operative ileus compared to the stapled side to side anastomosis group. Conclusion Reversal of ileostomy within 6 months of index surgery after adjuvant therapy could potentially reduce post-operative complications, and alleviate the burden on our healthcare system in the long run. A stapled side to side anastomosis should also be considered.

The thermal-mechanical deformations of CO2 mixture gases dry gas seal based on two-way thermal-fluid-solid coupling model

PurposeThis study aims to investigate the influence mechanism of thermal-mechanical deformations on the CO2 mixture gases dry gas seal (DGS) flow field and compare the deformation characteristics and sealing performance between two-way and one-way thermal-fluid-solid coupling models.Design/methodology/approachThe authors established a two-way thermal-fluid-solid coupling model by using gas film thickness as the transfer parameter between the fluid and solid domain, and the model was solved using the finite difference method and finite element method. The thermal-mechanical deformations of the sealing rings, the influence of face deformation on the flow field and sealing performance were obtained.FindingsThermal-mechanical deformations cause a convergent gap between the two sealing end faces, resulting in an increase in the gas film thickness, but a decrease in the gas film temperature and sealing ring temperature. The axial relative deformations of rotating and stationary ring end faces caused by mechanical and thermal loads in the two-way coupling model are less than those in the one-way coupling (OWC) model, and the gas film thickness and leakage rate are larger than those in the OWC model, whereas the gas film stiffness is the opposite.Originality/valueThis paper provides a theoretical support and reference for the operational stability and structural optimization design of CO2 mixture gases DGS under high-pressure and high-speed operation conditions.

NiCo@EG-based composite PCMs with boosted thermal conductivity and photothermal conversion efficiency for solar energy harvesting

The application of phase change materials (PCMs) in solar energy is hampered by challenges such as insufficient photothermal conversion efficiency, low thermal conductivity and leakage. In this study, a novel composite PCMs based on NiCo@EG were prepared to solve the problems of low thermal conductivity, high leakage rate and inefficient photothermal performance. The NiCo@EG is obtained through calcination of the product of Ni-Co-BTC in-situ on expanded graphite (EG). In the composite PCMs, the octadecanol (OD) acts as a latent heat storage unit, the EG retains its porous network structure as an encapsulating skeleton. The nickel and cobalt nanoparticles derived from Ni-Co-BTC bimetallic organic frameworks are uniformly fixed on the surface of the EG, which could not only construct multiple thermal conduction pathways, but also enhance the photon-trapping ability. Benefiting from the synergy effect of nickel, cobalt metal nanoparticles and EG, the prepared OD/NiCo@EG-550 composite PCMs display high latent heat (168.3 J/g), excellent photothermal conversion efficiency (98.71 %), and improved thermal conductivity of 12.873 W/(m·K). Furthermore, the composite PCMs demonstrate exceptional shape stability, thermal stability, and robust thermal reliability. In summary, the high-efficiency photothermal composite PCMs display significant potential in improving the utilization of solar energy.

Overexpression of OsRbohH Enhances Heat and Drought Tolerance through ROS Homeostasis and ABA Mediated Pathways in Rice (Oryza sativa L.).

Respiratory burst oxidase homologs (Rbohs) are the primary producers of reactive oxygen species (ROS), which have been demonstrated to play critical roles in plant responses to abiotic stress. Here, we explored the function of OsRbohH in heat and drought stress tolerance by generating overexpression lines (OsRbohH-OE). OsRbohH was highly induced by various abiotic stress and hormone treatments. Compared to wild-type (WT) controls, OsRbohH-OE plants exhibited enhanced tolerance to heat and drought, as determined by survival rate analyses and total chlorophyll content. Histochemical staining revealed that OsRbohH-OE accumulated less ROS. This is consistent with the observed increase in catalase (CAT) and peroxidase (POD) activities, as well as a reduced electrolyte leakage rate and malondialdehyde (MDA) content. Moreover, OsRbohH-OE exhibited enhanced sensitivity to exogenous abscisic acid (ABA), accompanied by altered expression levels of ABA synthesis and catabolic genes. Further analysis indicated that transgenic lines had lower transcripts of ABA signaling-related genes (OsDREB2A, OsLEA3, OsbZIP66, and OsbZIP72) under heat but higher levels under drought than WT. In conclusion, these results suggest that OsRbohH is a positive regulator of heat and drought tolerance in rice, which is probably performed through OsRbohH-mediated ROS homeostasis and ABA signaling.

Clean intermittent catheterization in multiple sclerosis patients: An adherence and long-term follow-up study

IntroductionClean Intermittent Catheterization (CIC) is considered as a gold standard of treatment for bladder emptying disorders. A large amount of literature on CIC for patients suffering from neurological disorders is available, but there is a lack of research specifically concerning multiple sclerosis (MS) patients. Our primary outcome was to determine the characteristics of our population (sex, EDSS and age when CIC was introduced). Our secondary outcomes were to determine adherence of CIC. MethodAs part of a multicenter, observational, retro-prospective study, data was collected from neuro-urologist consultation reports, and extracted from bladder diaries between 01/01/2000 and 31/03/24. MS patients, over 18 years, with the indication of CIC were included. Results195 patients (72.3% women) were included, with a mean age of 49 years old. The median of follow-up was 9 years. Median EDSS at the start of the study was 5.5. There was an adherence rate of 65.1%. Urinary leakage was present in 74.2% of patients prior to CIC and 31.6% following CIC. ConclusionCatheterization is mainly offered to patients with an EDSS between 0 and 7. Rate of adhesion is encouraging, with most patients still continuing to use CIC by the end of follow-up. During the follow-up, we observed a reduced leakage rate but CIC alone can not explain this improvement. Following studies should include a list of constraints and reasons of halted CIC.

Transsphenoidal Approach for Sellar Region Tumor : A Case Series

Introduction: Transsphenoidal approaches to the sellar region, with endoscopic or microscopic techniques, are regularly used to treat a diverse collection of pathologies. Case Description: Three patients with presenting symptoms visual disturbance and headache were evaluated with MRI that showes sellar region masses. All patients were undergo transphenoid tumor removal. Post operation evaluation show improvement in visual disturbance and headache with no adverse event after procedure. Discussion : Transsphenoidal endoscopic surgery (TSS) for functional pituitary adenomas yields better endocrinologic results for noninvasive macroadenomas. However, the rate of postoperative CSF leakage was greater with the endoscopic method. In patients with pituitary adenomas, younger age, dense visual field defect, and the preoperative absence of central or bilateral visual field abnormalities were predictive factors of visual field recovery following transsphenoidal approach-tumor excision. Overall survival rates are generally high, ranging from 91% to 98%. Conclusion: Transphenoid approach was a good surgical method for sellar region masses and show good outcomes after operation. Keyword : Sellar region masses; Surgical; Transsphenoid approach

Anastomotic leak after manual circular stapled left-sided bowel surgery: analysis of technology-, disease-, and patient-related factors.

Anastomotic leak rates after colorectal surgery remain high. In most left-sided colon and rectal resection surgeries, a circular stapler is utilized to create the primary bowel anastomosis. However, it remains unclear whether a relationship between circular stapler technology and anastomotic leak in left-sided colorectal surgery exists. A post-hoc analysis was conducted using a prospectively collected data set of patients from the 2017 European Society of Coloproctology snapshot audit who underwent elective left-sided resection (left hemicolectomy, sigmoid colectomy, or rectal resection) with a manual circular stapled anastomosis. Rates of anastomotic leak and unplanned intensive care unit stay in association with manual circular stapling were assessed. Patient-, disease-, geographical-, and surgeon-related factors as well as stapler brand were explored using multivariable regression models to identify predictors of adverse outcomes. Across 3305 procedures, 8.0% of patients had an anastomotic leak and 2.1% had an unplanned intensive care unit stay. Independent predictors of anastomotic leak were male sex, minimal-access surgery converted to open surgery, and anastomosis height C11 (lower third rectum) (all P < 0.050). Independent predictors of unplanned intensive care unit stay were minimal-access surgery converted to open surgery and American Society of Anesthesiologists grade IV (all P < 0.050). Stapler device brand was not a predictor of anastomotic leak or unplanned intensive care unit stay in multivariable regression analysis. There were no differences in rates of anastomotic leak and unplanned intensive care unit stay according to stapler head diameter, geographical region, or surgeon experience. In patients undergoing left-sided bowel anastomosis, choice of manual circular stapler, in terms of manufacturer or head diameter, is not associated with rates of anastomotic leak and unplanned intensive care unit stay.

An review of research on liquid hydrogen leakage: regarding China’s hydrogen refueling stations

Hydrogen is regarded as the premier energy source for future sustainability and renewability. However, its distinct physicochemical properties render it prone to explosions in the event of a leak. Therefore, there is a need for more comprehensive research dealing with hydrogen leakage, explosion scenarios, and risk assessment. This paper provides an overview of the current hydrogen policies adopted in China. It reviews the processes of hydrogen refueling station construction and the thermophysical mechanisms of liquid hydrogen leakage. In this regard, the effects of various factors, including leakage rate, leakage time, leakage hole size, wind direction and speed, and building location, on the hydrogen leakage rate are analyzed and evaluated. Additionally, the impacts of different factors on hydrogen explosion overpressure are reported, including hydrogen concentration, wind speed, obstacles, and ignition position, in addition to the current applications of quantitative risk assessment methods in hydrogen refueling stations. Finally, the limitations of current research on liquid hydrogen leakage and explosion accidents are highlighted, along with the shortcomings of current risk assessment methods for liquid hydrogen refueling stations.

Related factors of severe osteoporotic vertebral compression fracture and clinical outcomes of percutaneous kyphoplasty: A retrospective study.

Osteoporosis is the most common disease in postmenopausal women and the elderly, which can lead to vertebral compression fracture. To investigate the related factors of severe osteoporotic vertebral compression fracture (SOVCF) and evaluate the long-term outcomes of percutaneous kyphoplasty (PKP) for treating SOVCF through comparison with mild OVCF (MOVCF). From September 2015 to March 2019, 294 osteoporotic vertebral compression fracture (OVCF) patients treated with PKP were analyzed. Compression of the anterior margin of the fractured vertebral body beyond 2/3 of the original height was defined as SOVCF. Baseline data, clinical and imaging findings before and after surgery and at the last follow-up were recorded. Numerical Rating Scale (NRS) was used to evaluate low back pain, the Oswestry Disability Index (ODI) was used to evaluate activity of daily life. Anterior vertebral height (AVH) and local kyphosis angle (LKA) was used to evaluate radiographic outcomes. During the follow-up, patients with recurrent back pain were examined by MRI to identify new fractures and the incidence of adjacent vertebral fracture (AVF) was recorded. Age, sex, body mass index (BMI), dual energy X-ray absorptiometry based T value, duration of symptom, history of trauma, steroid use, and fracture site were collected for univariate logistic regression analysis Variables with a P-value of less than 0.05 were then included in multivariate analysis to determine the related factors for SOVCF. Logistic regression analysis indicated that longer duration of symptom (OR = 1.109, 95%CI: 1.038-1.185, P= 0.002), lower T value (OR = 0.332, 95%CI: 0.139-0.763, P= 0.001), and steroid use (OR = 31.294, 95%CI: 1.020-960.449, P= 0.049) were related factors of SOVCF. Compared with the MOVCF group, the SOVCF group had longer operation time (57.3 ± 13.51 minutes vs 44.9 ± 8.13 minutes, P< 0.001), more radiation exposure (39.9 ± 7.98 times vs 25.5 ± 4.01 times, P< 0.001), and higher cement leakage rate (55.81% vs 18.73%, P< 0.001). At the last follow-up, the SOVCF group had higher NRS (2.28 ± 0.85 vs 1.30 ± 0.71, P< 0.001), and ODI (16.23 ± 4.43 vs 12.88 ± 3.34, P< 0.001). After operation and at the last follow-up, the SOVCF group had higher LKA and lower AVH (all P< 0.05). The AVF rate at the last follow-up was higher in the SOVCF group at the last follow-up (4.78% vs 18.60%, P< 0.001). Lower T value, longer duration of disease, and steroid use were related factors of SOVCF. Compared with MOVCF, PKP for SOVCF had longer operation time, more radiation exposure, and higher cement leakage rate, and the long-term outcomes were worsen.

Quantitative assessment of double-cone seal leakage in canned reactor coolant pump based on double-cone ring stress

The double-cone seal is a crucial component of the canned reactor coolant pump (RCP), serving as a vital barrier to prevent coolant leakage. Its sealing status directly impacts the operational safety of the RCP. Given the intricate operational conditions and rigorous sealing requirements of RCP, there is a dearth of effective detection methods for minor leakage of double-cone seal. To address this issue, a quantitative assessment method for the leakage of double-cone seal based on double-cone ring stress is proposed. In this paper, the functional relationship between the double-cone ring stress and the specific pressure of the gasket seal is first derived. Subsequently, a leakage rate assessment model based on the double-cone ring stress is proposed by combining with the leakage rate expression of the metal gasket connection structure. Finally, the feasibility of the proposed method for the leakage detection of double-cone seal is verified by finite element simulation and leakage simulation test. The results demonstrate that the proposed method is capable of detecting small leakage conditions with a leakage rate in the order of 1 × 10−4 cm3·s−1, which is sufficient for the micro-leakage detection of double-cone seal.

Six-year analysis of 30-day post-operative leaks for primary sleeve gastrectomy: a MBSAQIP database study.

Sleeve gastrectomy is the most performed bariatric surgery. Post-operative gastric sleeve leaks, although rare, are dreaded complications. This study aims to perform an updated investigation of the factors associated with sleeve leaks. This retrospective cohort study analyzed 692,554 cases from the MBSAQIP database (2016-2021) with CPT code 43,775 for primary sleeve gastrectomy. We excluded emergency operations, conversions/revisions, endoscopic interventions, patient with prior foregut surgery, and open operations. Multivariate logistic regression analysis (STATA version 15) was performed to identify factors associated with sleeve gastrectomy leaks. Out of 692,554 patients, 600,910 (86.77%) patients underwent laparoscopic sleeve gastrectomy, and 91,644 (13.23%) patients underwent robotic sleeve gastrectomy. 1179 (0.17%) developed leaks within 30days; 177(0.19%) were in the robotic group and 1002 (0.17%) in the laparoscopic group with no significant difference in leak rates between two groups on multivariate analysis. Black patients had lower odds of having leaks as compared to white patients (Odds Ratio (OR): 0.68 (0.56-0.82); p < 0.01). Hispanic patients had lower odds of having leak as compared to non-Hispanics. Factors associated with higher leak odds (p < 0.05) included hypertension, GERD, smoking, immunosuppression, increased operating time, and albumin < 3.5g/dl. Higher odds of leaks were observed in years 2016-2019 vs 2020-2021 (OR: 1.44 (1.25-1.65), p < 0.01). Higher odds of leak in operations with general surgeons compared to bariatric surgeons was found (OR: 1.46 (1.04-2.02), p = 0.02); observed only on robotic group on subgroup analysis (OR: 2.2 (1.2-4.2), p = 0.02). Staple line reinforcement, oversewing, and performance of leak test showed no differences in leak rate. Bougie size and distance from pylorus were not associated with changes in leak rate. This study provides updated insights into the factors associated with sleeve leaks, reinforcing information gained from prior studies. A higher association of leak among general surgeons could represent a learning curve for new robotic general surgeons. The overall decreasing trend for gastric sleeve leak is encouraging and may be a sign of improved techniques.

426. TAILORED MANAGEMENT OF ANASTOMOTIC LEAK AFTER ESOPHAGECTOMY IN A SPECIALISED UNIT IN THE ERA OF HYBRID AND ENDOSCOPIC NOVELTIES

Abstract Tailored management of anastomotic leak after esophagectomy in a specialised unit in the era of hybrid and endoscopic novelties. Triantafyllou Alexandra1, Theodoropoulos Charalampos2, Eleni Kitsou1, Saliaris Konstantinos1, Karikis Ioannis1, Pachos Nikolaos1, Katsila Sofia3, Kakounis Konstantinos3, Triantafyllou Tania1, Xiromeritou Vasiliki3, Theodorou Dimitrios1 1. 1st Propaedeutic Surgical Department, Hippocratio General Hospital of Athens, University of Athens, Greece 2. Surgical Department, Tzaneio Hospital, Greece 3. Department of Gastroenterology, Hippocratio General Hospital of Athens, Greece Background Anastomotic leak following esophagectomy remains one of the most dreadful complications with high rates of morbidity and mortality. This study aims to delineate the incidence, therapeutic strategies, and associated outcomes of esophagogastric anastomotic leak in our unit. Methods We retrospectively analyzed prospectively collected data of patients diagnosed with anastomotic leak following esophagectomy. The treatment modalities and the patient outcomes are presented. Results 199 patients underwent esophagectomy between 2019 and 2023. Among them, 21 patients (10.6%) were diagnosed with anastomotic leakage. 17 out of these 21 patients (81.0%) were male, and the mean age was 58.6 years. 14 out of the 21 patients had cervical anastomosis (leak rate: 8.6%) and 7 patients intrathoracic anastomosis (leak rate: 18.9%). Significant reduction of the intrathoracic anastomotic leak rate was recorded within 2013 (0%) following revision of the anastomotic technique. No deaths were observed, and the average time to healing was 29.1 days. Endoscopic stenting was employed in 12 patients (57.1%), reoperation in 5 (23.8%), bedside wound exploration in 7 (4.8%) and one patient was treated conservatively. Besides stenting, 4 patients (19.0%) underwent percutaneous drainage procedures under radiological guidance. Conclusions Managing esophageal anastomotic leakage presents significant challenges. Optimal outcomes for anastomotic healing and patient survival are achieved through a multidisciplinary and individualised approach encompassing interventional radiology or endoscopy and/or reoperation in selected patients.

Evolution law of flow characteristics for straight pipeline after leaking

Aiming at the leakage problem of the fluid loop system for the thermal control system of spacecraft caused by the impact of micro-meteoroid and orbital debris, we investigate the dependence of the leak rate, pressure drop and flow characteristics before and after leaking on leak position, inlet pressure, and leaking aperture, calculated in a straight pipeline with single leakage, using stationary and transient three-dimensional computational fluid dynamics simulations with commercial software (FLUENT). The working fluid adopts single-phase water without gravity. It is found that the pressure increases obviously near the leak point, which is caused by the local peak of pressure. As the length between the leak point and the inlet becomes larger, the local peak of pressure and the dimensionless leak rate are smaller. When the inlet pressure increases, the leaked mass flow rate increases; however, the ratio of the leaked flow rate to inlet flow rate decreases. Furthermore, it is observed that the dependence of dimensionless leaking rate on dimensionless leaking aperture has a scaling relation with the scaling exponent approximating to 2, which may be related to the proportion of the vortex formed by the backward flow at the leak hole, the amplitude, and the affected length along the pipe of the local peak of pressure. This study is instructive and meaningful to the leak detection and plugging of fluid loop in space.

369. IMPACT OF THE COVID-19 PANDEMIC ON ESOPHAGEAL CANCER PATIENTS UNDERGOING ESOPHAGECTOMY: AN ACS-NSQIP DATABASE ANALYSIS

Abstract Background To cope with the increasing number of infected patients, medical access was restricted, and public facilities were closed throughout the COVID-19 pandemic. Early detection and treatment of esophageal cancer is critical for improved prognosis. However, the impact of pandemic-related medical access restrictions has not be evaluated to date for esophageal cancer. Therefore, the purpose of this research is to determine how the lockdown policy affected the surgical outcome of patients with esophageal cancer. Methods We analyzed patients who underwent esophagectomy for esophageal cancer between 2016-2022 using data obtained from the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP), including the procedure targeted esophagectomy database. The patients were stratified into two groups based on their operation date relative to pandemic (BEFORE COVID group: 2016-2019 vs AFTER COVID group: 2020-2022). Demographic data and perioperative outcomes were compared between the two groups. Statistical analysis included Chi-square tests for categorical variables and independent student T-tests for continuous data, with a significance threshold set at p &amp;lt; 0.05. Results Between 2016-2022, 7,198 esophageal cancer patients underwent esophagectomy. Clinical T4 increased significantly, but clinical N and pathologic T and N stages showed no impact. PET scan imaging, neoadjuvant chemotherapy and radiotherapy remained unchanged. The utilization of a minimally invasive approach rose substantially from 32.6% to 47.2% (p &amp;lt; 0.001). Positive margin rates increased from 7.5% to 9% (p = 0.03), and anastomotic leak rates increased from 14.1% to 17.2% (p &amp;lt; 0.001). Operative time, blood loss, and conversion rate showed no significant differences. Perioperative complications, including organ space surgical site infections and myocardial infarctions, significantly increased after COVID-19. Conclusion The COVID-19 pandemic altered the clinical staging of esophageal cancer patients undergoing esophagectomy, but it did not disrupt access to essential investigations and treatment. A notable increase in the implementation of minimally invasive techniques was observed after the pandemic. However, significant impacts were noticed on operative outcomes, including positive margin and leak rates.

Design and performance of indium seals for size-constrained tunable laser spectrometers.

Indium seals have been used extensively in ultra-high vacuum and cryogenic applications. Typically, these seals use indium alongside or in place of other metal gaskets in stainless-steel vacuum flanges, with some custom applications for flanges sealing directly with glass (optics or tubes). Here, we present the design and performance of three pressed indium seals (99.99% In) between aluminum and 0.5 in. diameter sapphire optics and aluminum and gold coated Kovar semiconductor packages (TO-66 and TO-39). Test fixtures were designed to mimic those of future tunable diode laser spectrometers for Earth, planetary, and manned spaceflight environmental monitoring applications. Successful high-hermeticity seals [<10-10 atm cc/s (He)] were achieved for all seals formed with sufficient pressure applied to allow indium to flow between mating surfaces. The hermeticity of the seals was maintained after temperature cycling (-10 to +80 °C, 20 cycles), with the optical seals surviving extended duration tests (-55 to +85 °C, per MIL-STD-883). Semiconductor packages (TO-39) subjected to these extended tests saw a moderate increase in leak rate [∼5 × 10-9 atm cc/s (He)]; however, further testing showed that either the glass-metal package seals or the indium were affected (the sample size was too small to draw firm conclusions for future applications). Overall, these results suggest long-term survivability of indium seals for Kovar-aluminum and sapphire-aluminum interfaces [>10 years at 10-10 atm cc/s (He)], where the coefficient of thermal expansion differs by approximately four times.

Temperature field analysis in tunnel construction ventilation with emphasis on duct leakage and thermal conductivity

Mechanical ventilation is the primary measure for cooling during construction of high geo-temperature tunnel. Based on heat transfer theory and characteristics of press-in ventilation, a comprehensive calculation model considering the influence of construction process is proposed, and the reliability of the model is verified by on-site test. The effects of duct leakage rate and thermal conductivity of different excavation length on temperature field distribution during construction ventilation were analyzed based on the prediction model. The following conclusions are drawn: As the excavation length increases, the duct outlet temperature first increases and then decreases. The duct outlet temperature is mainly affected by geo-temperature and boundary control temperature of working face, the air leakage rate and excavation length are not the main factors. The highest temperature in the duct is about 40 °C. The distance between the position of highest temperature and working face increases with the increase of excavation length and decreases with the increase of air leakage rate. With the increase of excavation length, the impact of thermal conductivity on outlet temperature of duct is first enhanced and then stabilized under the same excavation length. The heat-insulated duct can effectively reduce the outlet air temperature and prolong the service life of the duct, while minimizing the air leakage of the duct.

Tiny bubble triboelectric nanogenerator functionalized by liquid film rupture

As an important energy carrier, bubble commonly exists in undersea and liquid-gas two-phase systems. Efficiently utilizing the bubble energy is critical for potential applications in energy harvesting and sensing in two-phase environment. However, the micro liquid layer inhibits the complete contact and restricts the performance. Herein, we proposed strategies for tiny bubble triboelectric nanogenerator (TB-TENG) featuring liquid film rupture to eliminate the screen between bubble and dielectric layer. We carried out optimization design by invasively rupturing the liquid film, achieving stable open-circuit voltage peak and transferred charge of 8.3 V and 3 nC by a 110-μL bubble, with a high peak power density yielding the existing tube-based studies. Additionally, for noninvasive and spontaneous liquid film rupture, a scalable bubble regulator was fabricated, which integrated the irregularly dispersed bubbly flow into slug flow. We demonstrated the self-powered undersea gas leakage detection system combining the TB-TENG with the bubble regulator. Assisted with the good bubble regulation adaptability, the total leakage gas volume and rate were measured based on the voltage signal, with a varied leakage rate of 0.72–6 mL/min. The strategy provides insights for the related research in liquid-gas two-phase systems in nature and industry.