Low Leakage Rate Research Articles

Effects of La2O3, Nd2O3, NiO and CoO additions on the characteristics of SiO2–Al2O3–Y2O3–ZnO glass seals for intermediate temperature solid oxide fuel cells

In this study, nine SiO2–Al2O3–Y2O3–ZnO glasses were prepared to evaluate their applications in intermediate temperature solid oxide fuel cells (IT-SOFCs). La2O3, Nd2O3, NiO and CoO were added to the SiO2–Al2O3–Y2O3–ZnO glass samples to enlarge their CTE and improve their adhesion on SUS430 stainless steel. It was found that YASZ-4 glass was the best candidate as a sealant among the glasses evaluated. The glass transition points, softening points and crystallization peak temperature of the YASZ-4 glass were determined to be 748 °C, 897 °C and 969 °C, respectively, while the coefficient of thermal expansion (CTE) and electrical resistivity at 700 °C were reported to be 8.4 × 10−6 K−1 and 4.43 × 108 Ω-cm, respectively. Partial substitution of Y2O3 with La2O3 and NiO in the SiO2–Al2O3–Y2O3–ZnO glass was observed to increase its CTE and to enhance its adhesion on SUS430. A strict and more sensitive test condition was employed in this study to evaluate the leak rate, which included a helium gas pressure of 1 psi across the glass seals and a small top-loading pressure of 1.0 psi applied on the glass. The leak rate at 700 °C for the first three thermal cycles stabilized at 0.019 sccm/cm and then, slightly decreased to 0.012 sccm/cm after a subsequent 500 h soaking, indicating a trivial degradation of the sealing efficiency against long periods of operation. The XRD pattern of the YASZ-4 glass after a 500 h leakage test revealed that the fully amorphous nature was retained. The addition of 30 mol% LaCoO3 to YASZ-4 glass was further attempted to increase its CTE value; however, results did not show an improvement in terms of a low leak rate.

The Functional Outcomes of Coloanal and Low Colorectal Anastomoses with Reservoirs after Low Rectal Cancer Resections

Nearly half of patients undergoing low anterior rectal cancer resection have a functional sequelae after straight coloanal or low colorectal anastomoses (SA), including low anterior rectal resection syndrome, which combines stool fragmentation, urge incontinence, and incontinence. SA are responsible for anastomotic leakage rates of 0 to 29.2 per cent. Adding a colonic reservoir improves the functional results while reducing anastomotic complications. These colonic reservoir techniques include the colonic J pouch (CJP), transverse coloplasty (TC), and side-to-end anastomosis (STEA) procedures. The aim of this literature review was to compare the functional outcomes of these three techniques from a high level of evidence. CJP with a 4- to 6-cm reservoir is a good surgical option because it reduces functional impairments during the first year, and probably up to 5 years, but is not always feasible. TC appears to perform as well as CJP, is achievable in over 95 per cent of patients, but still with some doubts about a higher anastomotic leakage rate and worse functional outcomes. STEA appears equivalent to CJP in terms of morbidity and even better functional outcomes. STEA, with a terminal side segment size of 3 cm, is feasible in the majority of nonobese patients, combines good functional results, has low anastomotic leakage rates, and is easy to complete.

Why nuclear energy is sustainable and has to be part of the energy mix

Humanity must face the reality that it cannot depend indefinitely on combustion of coal, gas and oil for most of its energy needs. In the unavoidable process of gradually replacing fossil fuels, many energy technologies may be considered and most will be deployed in specific applications. However, in the long term, we argue that nuclear fission technology is the only developed energy source that is capable of delivering the enormous quantities of energy that will be needed to run modern industrial societies safely, economically, reliably and in a sustainable way, both environmentally and as regards the available resource base. Consequently, nuclear fission has to play a major role in this necessary transformation of the 21st century energy-supply system.In a first phase of this necessary global energy transformation, the emphasis should be on converting the major part of the world's electrical energy generation capacity from fossil fuels to nuclear fission. This can realistically be achieved within a few decades, as has already been done in France during the 1970s and 1980s. Such an energy transformation would reduce the global emissions of carbon dioxide profoundly, as well as cutting other significant greenhouse gases like methane. Industrial nations should take the lead in this transition.Because methane is a potent greenhouse gas, replacing coal-fired generating stations with gas-fired stations will not necessarily result in a reduction of the rate of greenhouse-gas emission even for relatively low leakage rates of the natural gas into the atmosphere.The energy sources popularly known as ‘renewables’ (such as wind and solar), will be hard pressed to supply the needed quantities of energy sustainably, economically and reliably. They are inherently intermittent, depending on backup power or on energy storage if they are to be used for delivery of base-load electrical energy to the grid. This backup power has to be flexible and is derived in most cases from combustion of fossil fuels (mainly natural gas). If used in this way, intermittent energy sources do not meet the requirements of sustainability, nor are they economically viable because they require redundant, under-utilized investment in capacity both for generation and for transmission.Intermittent energy installations, in conjunction with gas-fired backup power installations, will in many cases be found to have a combined rate of greenhouse-gas emission that is higher than that of stand-alone coal-fired generating stations of equal generating capacity. A grid connection fee, to be imposed on countries with a large intermittent generating capacity, should be considered for the purpose of compensating adjacent countries for the use of their interconnected electric grids as back-up power. Also, intermittent energy sources tend to negatively affect grid stability, especially as their market penetration rises.The alternative — dedicated energy storage for grid-connected intermittent energy sources (instead of backup power) — is in many cases not yet economically viable. However, intermittent sources plus storage may be economically competitive for local electricity supply in geographically isolated regions without access to a large electric grid. Yet nuclear fission energy will, even then, be required for the majority displacement of fossil fuels this century.

Experimental study of pipeline leak detection based on hoop strain measurement

Pipelines are widely used for the transport of a large variety of fluids, such as natural gas, across long distances. While pipelines provide a convenient mode of transportation of fluids, their safe usage is one of the foremost concerns especially if their contents are harmful to the environment or if the hosting area is prone to third-party intrusions. Thus, rapid detection and localization of pipeline leakage is paramount to the minimization of damage brought to the environment and stakeholders in the event of an unexpected leakage. In this work, a novel hoop strain based negative pressure wave (NPW) approach was used to detect and localize pipeline leakages in a 180 ft PVC pipeline equipped with five manually controllable leakage points. Using the new approach, both the arrival time of the NPW and the energy attenuation profile of the NPW can be used to detect and localize leakages with higher accuracy and in a wider variety of situations. The time of arrival approach allowed accurate (within 7.33% error) and repeatable localization of the leakage points; however, using the energy attenuation of the NPW, leakages with low leakage rates (<5 lpm) can also be detected, albeit at the cost of inaccuracies at the inlet and outlet of the pipeline (8.3% error in the ends vs. 4.3% error in the body). Copyright © 2014 John Wiley & Sons, Ltd.

Post-experimental analysis of a solid oxide fuel cell stack using hybrid seals

A post-experimental analysis of a SOFC stack is presented. The stack was operated for 1800 h at 700 °C with air and hydrogen and contained hybrid glass-Thermiculite 866 seals. The goal of this work was to investigate the sealing microstructure and possible corrosion during mid-term operation. It was found that hybrid seals could effectively compensate for manufacturing tolerances of cells and other components due to the compliance of the glass layer. Additionally, different interfaces were investigated for corrosion. Corrosion was not observed at two-phase interfaces such as Crofer 22 APU/glass, glass/electrolyte and glass/Thermiculite 866. The three-phase interface between Crofer 22 APU/glass/hydrogen exhibited no corrosion. Some evidence of non-systematic corrosion was found at the Crofer 22 APU/glass/air interface. The possible reasons for the corrosion are discussed. Lastly, dual exposure to humid hydrogen and air of the 0.2 mm Crofer 22 APU interconnect had no detrimental effect on the corrosion compared to air exposure. Overall the hybrid seals used in combination with the thin interconnects were found to be a promising solution due to the low leak rate and limited material interactions.

A polymer-metal two step sealing concept for hermetic neural implant packages.

In this paper, we introduce a technique for double-sealed ceramic packages for the long-term protection of implanted electronics against body fluids. A sequential sealing procedure consisting of a first step, during which the package is sealed with epoxy, protecting the implant electronics from aggressive flux fumes. These result from the application of the actual moisture barrier which is a metal seal applied in a second step by soft soldering. Epoxy sealing is carried out in helium atmosphere for later fine leak testing. The solder seal is applied on the laboratory bench. After the first sealing step, a satisfactory barrier for moisture is already achieved with values for helium leakage of usually LHe = 6·10(-8) mbar 1 s(-1). After solder sealing, a very low leakage rate of LHe ≤ 1·10(-12) mbar 1 s(-1) was found, which was the lower detection limit of the measurement setup, suggesting excellent hermeticity and hence moisture barrier. Presuming an implant package volume of V ≥ 0.5 cm(3), the time to reach a critical humidity of p = 5000 ppm H2O inside the package will be longer than any anticipated average life of human patients.

Behavior of Geosynthetic Clay Liners due to the Migration of Heavy Metal

To protect the underlying soil and groundwater from landfills, the landfills are commonly lined with layered liner systems. Geosynthetic clay liners (GCL) have been increasingly used in the landfill liner systems to substitude the traditional compacted clay liners (CCL) because of their low cost, easily construction behavior and low leakage rate. To study the behavior of the GM+GCL liner system used in China due to the migration of Pb2+, we introduce in detail GM+GCL liner systems proposed by the Chinese specification. Then one dimensional finite layer model is used to investigate the anti-pollution behavior of the CM+GCL composite liner systems, with the focuses on the heavy metal Pb2+. It could be concluded that the main migration way through the GM+GCL composite liner system is that the transport of Pb2+through a GM+GCL composite liner system of a landfill cover takes place primarily through the holes in the GM. The findings provide useful reference for preventing, controlling and treating groundwater pollution in the GM+GCL liner system technically and scientifically.

A piezoelectric microvalve with a flexure-hinged driving frame and microfabricated silicon sealing pair

This paper describes a piezoelectric microvalve for attitude control of micro-satellite with a mass in the range of 20–100kg. The microvalve comprises of a driving mechanism with a flexure-hinged frame and a valve body with a silicon sealing pair. The silicon valve core with sealing rings can achieve a low leak rate with a small structural deformation. The driving mechanism using a flexure-hinged frame and piezoelectric actuators assures the microvalve normally closed and leads to a fast response of the microvalve. The response time of the driving mechanism is characterized to be as small as 0.6ms. A maximum flow rate of 3100mL/min is achieved at an inlet pressure of 0.6MPa while applied with a maximum voltage of 200V. The static power consumption is 48mW with a driving voltage of 200V, and the dynamic power consumption is approximately 0.9W at 100Hz.

Su1815 Hiatal Hernia Repair in Bariatric Surgery Patients: The Impact of Preoperative Imaging

patients. The median operative time was 409 minutes with a median blood loss of 150 cc. The median length of stay was 9 days. When the two cohorts were compared, the only statistically significant difference was operative time p <0.003. There was no significant difference in gender, age, blood loss, LOS, or receipt of NT. Conclusions: We demonstrate that atrial fibrillation is an uncommon occurrence after RAIL. The low leak rate limits our ability to comment on the clinical relevance of atrial fibrillation as a predictor of anastomotic leak but in this series it does not appear to be predictive of a leak.

Mass Point Leak Rate Technique with Uncertainty Analysis

The mass point leak rate technique is often the methodology of choice for quantifying leak rates as it uses simple elementary measurements, applies to gas systems of low mass, proves effective for low leak rates, and does not rely on test-gas conversions. In this methodology, a number of instantaneous mass measurements are calculated through samples of volume, pressure, gas composition, and temperature measurements over time. A regression analysis of the corresponding mass-time sample set yields the leak rate of the system. A detailed uncertainty analysis is paramount for a complete, experimental characterization of the leak rate and previously was not fully implemented in the mass point leak rate method. Recent advancements in regression uncertainty analysis by propagation of errors afford the ability to quantify the uncertainty with estimates of covariance in the regression results. The mass point leak rate technique with the associated detailed measurement uncertainty analysis offers the ability to quantify both the leak rate and the uncertainty associated with the leak rate value. Detailed herein is the development of the methodology and a detailed uncertainty analysis that includes both precision (repeatability) and bias (systematic) error. Alternative leak rate methods are also discussed for comparison purposes. An example in the methodology is presented.

Thoraco-lumbar traumatic vertebral fractures augmentation by osteo-conductive and osteo-inductive bone substitute containing strontium–hydroxyapatite: our experience

The aim of our study was to evaluate the effectiveness of osteointegrable strontium-hydroxyapatite (Sr-HA) bone cement in the treatment of thoracolumbar traumatic vertebral fractures by percutaneous vertebroplasty (VTP). We treated 35 patients [29 (82.85 %) men, 6 (17.14 %) women, mean age 34.05 ± 8.36 years (range 21-54 years)] with single type A1.1 and A1.2 thoracolumbar traumatic vertebral fracture without endospecal bone fragments. Pain intensity was evaluated before and at 1 day; 1 week; and 1, 6, and 12 months after VTP by a 10-point visual analog scale (VAS) score (0 = no pain, 10 = unbearable pain). Physical status and quality of life were evaluated by Oswestry Disability Index (ODI) questionnaire before and 1, 6, and 12 months after VTP. Procedural technical success was achieved in all patients with no deaths observed during follow-up. In three patients (8.57 %), postprocedural CT showed cement leakages: one intradiscal and two in venous plexus. No adjacent vertebral body fractures nor intrasomatic recollapse was detected. The VAS and ODI scores showed a statistically significant reduction 1 week after procedure (P value <0.0001) with a progressive statistically significant reduction during follow-up (P value <0.0001). Twenty-three patients (65.71 %) assigned a value of 0 to the VAS scale at 1 year after treatment. Strontium-hydroxyapatite bone cement is an effective and safe bone filler in percutaneous vertebroplasty with low leakage rate and absence of major complications when performed by a skilled equipe. It allows an immediate and long-lasting stabilization with a significant pain reduction and quality of life improvement.

The CoreValve US Pivotal Trial

Transcatheter aortic valve replacement (TAVR) has been developed as a less-invasive approach to address patients at high risk to extreme risk for surgical aortic valve replacement. The CoreValve US trial enrolled patients with symptomatic severe aortic stenosis into 2 separate cohorts: an extreme-risk cohort and a high-risk cohort. The study of transfemoral TAVR using the CoreValve system in extreme-risk patients achieved its primary end point of all-cause mortality or stroke at 1 year. This was achieved with a low stroke rate and low paravalvular leak rate that improved with time. The CoreValve high-risk trial is the only randomized trial of TAVR vs surgical aortic valve replacement to show superior survival of TAVR. This was achieved with a numerically lower rate of major stroke and statistically superior changes in aortic valve function from baseline to 1 year.

V-Loc urethro-intestinal anastomosis during robotic cystectomy with orthotopic urinary diversion

Robotic-assisted radical cystectomy (RARC) is an emerging minimally invasive alternative for the treatment of invasive bladder cancer. The V-loc (Covidien, Mansfield, MA) suture is a unidirectional barbed suture that provides even distribution of tension. We determined the rate of urinary leak at the urethro-intestinal anastomosis following orthotopic neobladder construction performed with V-loc suture. We retrospectively reviewed charts on all patients that underwent RARC with orthotopic neobladder urinary diversion performed with a V-loc suture from February 2010 to February 2012. The urethro-intestinal anastomosis was evaluated for urinary leak by cystogram at 3 to 4 weeks, postoperatively. In total, 11 patients were available for analysis. The mean patient age was 57.2 years (range: 47-71). The average clinical follow-up was 8 months (range: 4-15). On surgical pathology, 8 (73%) patients had pT2 or less disease, 3 (27%) had pT3/T4 disease, and 1 (9%) had N+ disease. The mean intraoperative blood loss was 315 mL (range: 150-600) and the average operative time was 496 minutes (range: 485-519). No patient (0%) demonstrated a urinary leak at the urethro-intestinal anastomosis on postoperative cystogram. Eight patients (73%) were continent by 4 months, postoperatively. Orthotopic neobladder urethro-intestinal anastomosis can be performed effectively and safely with V-loc suture with an acceptably low urinary leak rate.

SiO2–Al2O3–Y2O3–ZnO glass sealants for intermediate temperature solid oxide fuel cell applications

In this study, eleven alkaline earth metal and B2O3-free SiO2–Al2O3–Y2O3–ZnO glass sealants were prepared. The thermal stability, adhesion, and sealing properties of the glass systems with respect to SUS430 stainless steel (SUS430) were assessed for use in intermediate temperature solid oxide fuel cells (ITSOFCs). The glass transition points fell in the range of 694 °C and 833 °C, while the glass softening points, varying from 725 °C to 885 °C, decreased linearly with the ZnO/SiO2 ratio. Among the glasses evaluated, the YAS1-50, YAS4-50, YAS5-50, and YAS5-90 glasses coupled with SUS430 showed fine adhesion and no detectable inter-diffusion across the interface. The coefficient of thermal expansion (CTE) of the YAS5-50 glass escalated from 7.01 to 9.30 × 10−6/K with 50 wt% Bi1.5Y0.5O3 (BYO) fillers. The leak rates of the composite seals comprising the YAS5-50 glass and 50 wt% BYO fillers were measured at 700 °C after joining at 850 °C. The measurement used helium with a pressure at 1 psi across the glass seals and a slight load of 1.0 psi to minimize compressive seal effect on the glass. It appeared that a low leak rate of 0.052 sccm/cm was obtained and stayed unchanged as the system was soaked at 700 °C for 500 h, indicating a fine thermal stability against the extended duration benefited from the limited crystallization of the YAS5-50 glass. This promising long-term stability qualified the glass for use as SOFC seal.

Electrical Test Structure for the Measurement of Hermeticity in Electronic and MEMS Packages With Small Cavity Volumes

The design, fabrication, and characterization of a piezoresistive membrane deflection test structure for the electrical evaluation of hermeticity in low cavity volume packages is discussed. This test structure uses the zero-level silicon cap as a deflecting membrane to electrically monitor changes in package cavity pressure over time. The hermeticity of the package can then be determined in real-time and low leak rates can be measured using a pressurization stage, which also accelerates the test. The minimum detectable leak rate of the test structure without acceleration has been measured at 6.9× 10-12 atm·cm3·s-1, which is two orders of magnitude lower than the limit of a traditional helium fine leak test.

The Safety of Laparoscopic Hand-Sutured Gastrojejunostomy in Gastric Bypass for the Treatment of Morbid Obesity

Laparoscopic Roux-en-Y gastric bypass is the most commonly adopted bariatric procedure. The predominant majority of surgeons construct the anastomoses using stapled techniques. We describe our technique of complete laparoscopically sutured gastrojejunal anastomosis (GJA) and its outcomes. Electronic database was used to collect data retrospectively for patients undergoing laparoscopic gastric bypass at the senior author's bariatric institutions. The results shown represent median (interquartile range). Between April 2002 and April 2012, 1,754 consecutive patients (78% female) aged 43 (35-50) years with BMI 51 (44.5-56.7) kg/m(2) underwent laparoscopic gastric bypass (1,679 primary bypasses, 75 revision procedures). All the GJA were hand-sutured. The operative mortality was 0.17%. Four patients (0.22%) developed GJA/gastric pouch leak of whom two died, while a further three patients (0.17%) needed endoscopic dilatation of GJA stricture during the initial 2years after surgery. In the hands of an experienced laparoscopic surgeon, laparoscopic hand-sutured GJA in patients undergoing gastric bypass is safe and effective with very low anastomotic leak and stricture rates.

Microbubble-mediated ultrasound therapy: a review of its potential in cancer treatment

The inherently toxic nature of chemotherapy drugs is essential for them to kill cancer cells but is also the source of the detrimental side effects experienced by patients. One strategy to reduce these side effects is to limit the healthy tissue exposure by encapsulating the drugs in a vehicle that demonstrates a very low leak rate in circulation while simultaneously having the potential for rapid release once inside the tumor. Designing a vehicle with these two opposing properties is the major challenge in the field of drug delivery. A triggering event is required to change the vehicle from its stable circulating state to its unstable release state. A unique mechanical actuation type trigger is possible by harnessing the size changes that occur when microbubbles interact with ultrasound. These mechanical actuations can burst liposomes and cell membranes alike allowing for rapid drug release and facilitating delivery into nearby cells. The tight focusing ability of the ultrasound to just a few cubic millimeters allows for precise control over the tissue location where the microbubbles destabilize the vehicles. This allows the ultrasound to highlight the tumor tissue and cause rapid drug release from any carrier present. Different vehicle designs have been demonstrated from carrying drug on just the surface of the microbubble itself to encapsulating the microbubble along with the drug within a liposome. In the future, nanoparticles may extend the circulation half-life of these ultrasound triggerable drug-delivery vehicles by acting as nucleation sites of ultrasound-induced mechanical actuation. In addition to the drug delivery capability, the microbubble size changes can also be used to create imaging contrast agents that could allow the internal chemical environment of a tumor to be studied to help improve the diagnosis and detection of cancer. The ability to attain truly tumor-specific release from circulating drug-delivery vehicles is an exciting future prospect to reduce chemotherapy side effects while increasing drug effectiveness.

Evolution of Transoral Surgery

Transoral surgery may be used to approach pathologies at the craniocervical junction. However, the need for this approach has decreased over the past few decades. To assess the outcome and complications of transoral surgery and extended transoral approaches at a single UK center between 1980 and 2011. A retrospective review was performed of 495 ventral midline operations (between 1980 and 2004) and prospective review of 38 operations (2004-2011) in a total of 479 patients. Trends in surgery and factors associated with good or bad outcome were assessed over this 30-year period. Of 533 operations, the most frequently performed surgeries were simple transoral surgery (321 operations), transoral surgery with splitting of the palate (107 operations), open-door maxillotomy (58 operations), and mandibulotomy (11 operations). Since the 1990s, there has been a steady decrease in the number of operations performed, mainly due to the decrease in the number of patients with rheumatoid arthritis presenting for surgery. The incidence of craniocervical junction tumors remained constant. The number of complications was significantly associated with the preoperative neurological status, and more complications were seen in myelopathic rheumatoid patients as well as a greater trend in congenital basilar invagination. The rates of pharyngeal infection (0.6%) and cerebrospinal fluid leak (0.3%) for standard transoral surgery were extremely low. The number of transoral and associated operations has decreased over time. Transoral surgery is now mainly indicated for ventral midline tumors such as chordomas. Transnasal endoscopic techniques show promise, but a major advantage of standard transoral surgery is the low cerebrospinal fluid leak and infection rates.

Geochemistry of Wellbore Integrity in CO2 Sequestration: Portland Cement-Steel-Brine-CO2 Interactions

### Geochemistry and wellbore integrity in CO2 sequestration Effective geologic sequestration of CO2 requires long-term storage with very low leak rates. Injection wells are an obvious leakage pathway for CO2 because they perforate the confining caprock. In addition, sequestration sites are likely to use monitoring wells to assess performance and, in the case of depleted oil and gas fields, may contain 10s to 1000s of older operating and abandoned wells. All wells may have leakage pathways due to faulty construction or other defects. However, it is the subject of this chapter to consider whether geochemical reactions induced by CO2 could result in damage to wells and the development of leaks. This concern is based on the thermodynamic incompatibility of CO2-saturated fluids with the Portland cement and steel used to prevent fluid migration to the surface. Portland cement is an alkaline substance with pH > 12.5 and is not in equilibrium with CO2-bearing fluids (pH < 6). Low-carbon steel used as well casing is subject to aggressive corrosion by carbonic acid. As a result, well integrity has been a central issue in risk analysis of sequestration sites (Gasda et al. 2004; IPCC 2005; Viswanathan et al. 2008; Nordbotten et al. 2009). At the outset, it is important to bear in mind that geochemical reactions alone do not yield insight into wellbore integrity, which is governed primarily by the effective permeability of the Portland cement seal and the mechanical integrity of the system. Thus the significance of chemical reactions must be considered with respect to their impact to changes in permeability or in strength. There is an unfortunate tendency in the literature to not distinguish between reaction and impact. Often CO2 reactions are described as “degradation of cement” or “corrosion of cement” without adequately defining what these terms …

Fabrication, assembly, and testing of a MEMS-enabled micro gas compressor for a 4:1 pressure ratio

This study describes the fabrication, assembly, and testing of a micro gas compressor. The compressor is formed by MEMS-based check valves coupled to a Kapton membrane driven by a mechanically amplified piezoelectric actuator. The valves are surface machined on a silicon substrate using polyimide as the structural material and copper as the sacrificial material. This design allows valves with low leak rates, low compressor dead volume, and the high compressible volume required to generate the pressure levels required of numerous applications including cryogenic cooling. The assembled compressor is tested with voltages over the range of 25–180V and frequencies over the range of 25–700Hz. A maximum pressure ratio of 4.3:1 is found when the actuator provides a maximum displacement of 156μm, while the maximum flow-rate through the compressor of 51 standard cubic cm per minute (sccm) is observed when the compressor is operating at its resonant frequency.