Gradual Pressure Research Articles

Genetic insights into an Apennine population of the Italian red deer

The red deer Cervus elephus has been a common species in Italy until the Middle Ages and the Renaissance, when its distribution range started to considerably decrease, due to gradual deforestation and hunting pressure. Afterwards, the red deer has been reintroduced to many regions of the world, including Italy. In the Italian Apennines, the Acquerino-Cantagallo Natural Reserve (ACQUERINO) hosts one of the largest peninsular red deer populations, originated from a series of successful reintroductions. In this study, we meant to detect the level of genetic variability of Acquerino-Cantagallo Natural Reserve deer population and to investigate the genetic relationships with the other Italian and European populations. We identified five mitochondrial DNA control region (D-loop) haplotypes, four falling in lineage A and one falling in lineage C, derived from at least two maternal lineages, confirming that ACQUERINO population should be the result of multiple reintroductions. Haplotype diversity (H = 0.50) and nucleotide (π = 0.004) diversity were low, but included into the deer range values. ACQUERINO population showed low levels of genetic diversity when compared to other European and Mediterranean populations, confirming that this expanding population may have been generated from a low number of founders.

Postmortem Retrograde Contrasted Infusion in Thoracic Duct Outflow: Imaging Effectiveness Analysis.

BackgroundThoracic duct (TD) anomaly can be quite variable and dangerous in surgical interventions in the neck region as there are numerous variations in its formation and topography. This highlights the importance of full knowledge about the TD and its anatomical variations. Thus, it is important to emphasize that the lack of anatomical-clinical knowledge or surgical skill during an intervention can significantly hamper successful results. The present study aimed to perform radiopaque contrast infusion into the TD of intact cadavers, either formalinized or refrigerated, to evaluate possible lymphatic architecture patterns via reverse lymphography.MethodologyTD dissection was performed on 13 cadaveric specimens. After isolating the lymphatic vessel, it was cannulated with an nº 4 urethral probe fixed with cordonnet cotton. Then, a 10 mL syringe was attached to the urethral probe and the radiopaque iodinated contrast was injected into the TD under constant and gradual manual pressure.ResultsTD outflow was detected on the posterior surface of the junction between the internal jugular and the left subclavian veins, either as direct outflow (in 10 cases) or as an arc (in three cases). Reverse contrast progression was impossible in each of the attempts, probably due to valvular resistance and lumen obliteration, which completely prevented pressure infusion into the thoracic and abdominal parts of the TD.ConclusionsWe emphasize the impracticality of obtaining postmortem radiopaque images via retrograde contrast injection into the TD in formalinized or refrigerated bodies.

CO2 plume and pressure monitoring through pressure sensors above the caprock

Commercial-scale development of CO2 geological storage necessitates robust and real-time monitoring methods to track the injected CO2 plume and provide assurance of CO2 storage. Pressure monitoring above the injection zone is a method to detect potential CO2 leaks into overlying formations. We present a generic CO2 storage model with a single injector to predict pressure changes above the caprock due to both fast hydraulic communication and partially undrained loading, the latter often neglected in reservoir simulation. The simulation used a compositional simulator coupled with geomechanics to solve the poroelastic equations in the entire storage complex. The results show that changes of pore pressure above the caprock caused by partially undrained loading reach up to ∼15 kPa within ∼10 days followed by a gradual decay with time. This is about 1% of the pressure increase in the injection zone. Furthermore, the pressure changes above the caprock are closely related to the advance of the CO2 plume. The results also include forward simulations considering the presence of: a fault either with high or low permeability, a poorly isolated abandoned well, a leaky injector, and a second injector. Fluid flow through high permeability paths across the caprock favors a ∼one order of magnitude higher, yet more gradual pressure increase than the base case with a fully covering caprock. Pressure monitoring above the caprock is a feasible technology to track the CO2 plume, requires high precision pressure measurements, and must account for partially undrained poroelastic loading to interpret correctly measured pressure signals in the field.

Repeated endo-tracheal tube disconnection generates pulmonary edema in a model of volume overload: an experimental study

BackgroundAn abrupt lung deflation in rodents results in lung injury through vascular mechanisms. Ventilator disconnections during endo-tracheal suctioning in humans often cause cardio-respiratory instability. Whether repeated disconnections or lung deflations cause lung injury or oedema is not known and was tested here in a porcine large animal model.MethodsYorkshire pigs (~ 12 weeks) were studied in three series. First, we compared PEEP abruptly deflated from 26 cmH2O or from PEEP 5 cmH2O to zero. Second, pigs were randomly crossed over to receive rapid versus gradual PEEP removal from 20 cmH2O. Third, pigs with relative volume overload, were ventilated with PEEP 15 cmH2O and randomized to repeated ETT disconnections (15 s every 15 min) or no disconnection for 3 h. Hemodynamics, pulmonary variables were monitored, and lung histology and bronchoalveolar lavage studied.ResultsAs compared to PEEP 5 cmH2O, abrupt deflation from PEEP 26 cmH2O increased PVR, lowered oxygenation, and increased lung wet-to-dry ratio. From PEEP 20 cmH2O, gradual versus abrupt deflation mitigated the changes in oxygenation and vascular resistance. From PEEP 15, repeated disconnections in presence of fluid loading led to reduced compliance, lower oxygenation, higher pulmonary artery pressure, higher lung wet-to-dry ratio, higher lung injury score and increased oedema on morphometry, compared to no disconnects.ConclusionSingle abrupt deflation from high PEEP, and repeated short deflations from moderate PEEP cause pulmonary oedema, impaired oxygenation, and increased PVR, in this large animal model, thus replicating our previous finding from rodents. Rapid deflation may thus be a clinically relevant cause of impaired lung function, which may be attenuated by gradual pressure release.

Результаты применения микроимпульсной циклофотокоагуляции в лечении пациентов с первичной открытоугольной глаукомой

Aim: to evaluate the clinical efficacy and safety of using micropulse cyclophotocoagulation (MP-CPC) for the treatment patients with mild and moderate stages of primary open-angle glaucoma (POAG). Patients and Methods: the clinical study included 56 patients (62 eyes) with POAG, 49–82 years old. The mild stage of glaucoma was detected in 33 eyes and the moderate stage — in 29 eyes. The level of intraocular pressure (IOP) before surgery ranged from 25 to 38 mm Hg (mean 29.2±2.8 mm Hg). All patients underwent MP-CPC according to the standard technique with the use of the Cyclo G6 Glaucoma Laser System and the MicroPulse P3 probe (IRIDEX, USA). The follow-up period was 6 months. Results: no complications were reported after the surgeries. The mean level of intraocular pressure at day 1 after surgery was 21.7±1.9mm Hg. A gradual intraocular pressure decrease was recorded by the third week after the surgical treatment, and its stabilization to 17.9±1.9 mm Hg occurred by the sixth month of observation in 94% of the eyes. At day 1 after the surgery, the reduction of intraocular pressure was more pronounced in patients with dark (brown) color of the iris in comparison with patients who had light (blue) color of the iris. It was found that up to 6 months after the surgery, the group of patients under 60 years of age had a more noticeable postoperative hypotensive effect when compared to the patient group over 71 years. Conclusion: MP-CPC was an effective and safe operation for normalizing intraocular pressure in most of the patients with mild to moderate stages of POAG during the 6-month follow-up period. Considering the minimization of the surgical trauma, MP-CPC can prolong the hypotensive effect and preserve visual functions in patients with mild to moderate stages of glaucoma in the near-term future (up to 6 months) after the surgical treatment. Keywords: micropulse cyclophotocoagulation, primary open-angle glaucoma, mild stage, moderate stage, intraocular pressure. For citation: Egorov V.V., Postupaev A.V., Postupaeva N.V. The results of using micropulse cyclophotocoagulation for the treatment of patients with primary open-angle glaucoma. Russian Journal of Clinical Ophthalmology. 2022;22(4):204–209 (in Russ.). DOI: 10.32364/2311-7729- 2022-22-4-204-209.

Developing Process for Multi-modal Sustained Pressure Trigger Point

Introduction: Myofascial torment disorder presents as clinically alluded torment, a restricted scope of movement in the joints, and is related with a nearby jerk reaction and engine endplates following mechanical incitement of the MTRP.
 Objective: Of the present disclosure is to provide a multi-modal sustained pressure trigger point release process intended to treat myo-fascial trigger points (MTrP’s) in both static as well as dynamic ways.
 Method: The multimodal sustained pressure trigger point release process comprises the steps of keeping the muscle in shortened or contracted position and applying apply gradual pressure over the MTrP using the thumb pad of the dominant side.
 Result: The MTrP is located by superficial palpation throughout the length of the muscle.
 Conclusion: The patients who were observed after giving treatment under MRTP have showed better recovery when compared with those who were not given such treatment.

A more gradual positive end-expiratory pressure increase reduces lung damage and improves cardiac function in experimental acute respiratory distress syndrome.

Increases in positive end-expiratory pressure (PEEP) or recruitment maneuvers may increase stress in lung parenchyma, extracellular matrix, and lung vessels; however, adaptative responses may occur. We evaluated the effects of PEEP on lung damage and cardiac function when increased abruptly, gradually, or more gradually in experimental mild/moderate acute respiratory distress syndrome (ARDS) induced by Escherichia coli lipopolysaccharide intratracheally. After 24 h, Wistar rats (n = 48) were randomly assigned to four mechanical ventilation strategies according to PEEP levels: 1) 3 cmH2O for 2 h (control); 2) 3 cmH2O for 1 h followed by an abrupt increase to 9 cmH2O for 1 h (no adaptation time); 3) 3 cmH2O for 30 min followed by a gradual increase to 9 cmH2O over 30 min then kept constant for 1 h (shorter adaptation time); and 4) more gradual increase in PEEP from 3 cmH2O to 9 cmH2O over 1 h and kept constant thereafter (longer adaptation time). At the end of the experiment, oxygenation improved in the shorter and longer adaptation time groups compared with the no-adaptation and control groups. Diffuse alveolar damage and expressions of interleukin-6, club cell protein-16, vascular cell adhesion molecule-1, amphiregulin, decorin, and syndecan were higher in no adaptation time compared with other groups. Pulmonary arterial pressure was lower in longer adaptation time than in no adaptation (P = 0.002) and shorter adaptation time (P = 0.025) groups. In this model, gradually increasing PEEP limited lung damage and release of biomarkers associated with lung epithelial/endothelial cell and extracellular matrix damage, as well as the PEEP-associated increase in pulmonary arterial pressure.NEW & NOTEWORTHY In a rat model of Escherichia coli lipopolysaccharide-induced mild/moderate acute respiratory distress syndrome, a gradual PEEP increase (shorter adaptation time) effectively mitigated histological lung injury and biomarker release associated with lung inflammation, damage to epithelial cells, endothelial cells, and the extracellular matrix compared with an abrupt increase in PEEP. A more gradual PEEP increase (longer adaptation time) decreased lung damage, pulmonary vessel compression, and pulmonary arterial pressure.

Effect of RecA inactivation and detoxification systems on the evolution of ciprofloxacin resistance in Escherichia coli.

BackgroundSuppression of SOS response and overproduction of reactive oxygen species (ROS) through detoxification system suppression enhance the activity of fluoroquinolones.ObjectivesTo evaluate the role of both systems in the evolution of resistance to ciprofloxacin in an isogenic model of Escherichia coli.MethodsSingle-gene deletion mutants of E. coli BW25113 (wild-type) (ΔrecA, ΔkatG, ΔkatE, ΔsodA, ΔsodB), double-gene (ΔrecA-ΔkatG, ΔrecA-ΔkatE, ΔrecA-ΔsodA, ΔrecA-ΔsodB, ΔkatG-ΔkatE, ΔsodB-ΔsodA) and triple-gene (ΔrecA-ΔkatG-ΔkatE) mutants were included. The response to sudden high ciprofloxacin pressure was evaluated by mutant prevention concentration (MPC). The gradual antimicrobial pressure response was evaluated through experimental evolution and antibiotic resistance assays.ResultsFor E. coli BW25113 strain, ΔkatE, ΔsodB and ΔsodB/ΔsodA mutants, MPC values were 0.25 mg/L. The ΔkatG, ΔsodA, ΔkatG/katE and ΔrecA mutants showed 2-fold reductions (0.125 mg/L). The ΔkatG/ΔrecA, ΔkatE/ΔrecA, ΔsodA/ΔrecA, ΔsodB/ΔrecA and ΔkatG/ΔkatE/ΔrecA strains showed 4–8-fold reductions (0.03–0.06 mg/L) relative to the wild-type. Gradual antimicrobial pressure increased growth capacity for ΔsodA and ΔsodB and ΔsodB/ΔsodA mutants (no growth in 4 mg/L) compared with the wild-type (no growth in the range of 0.5–2 mg/L). Accordingly, increased growth was observed with the mutants ΔrecA/ΔkatG (no growth in 2 mg/L), ΔrecA/ΔkatE (no growth in 2 mg/L), ΔrecA/ΔsodA (no growth in 0.06 mg/L), ΔrecA/ΔsodB (no growth in 0.25 mg/L) and ΔrecA/ΔkatG/ΔkatE (no growth in 0.5 mg/L) compared with ΔrecA (no growth in the range of 0.002–0.015 mg/L).ConclusionsAfter RecA inactivation, gradual exposure to ciprofloxacin reduces the evolution of resistance. After suppression of RecA and detoxification systems, sudden high exposure to ciprofloxacin reduces the evolution of resistance in E. coli.

Autoignition of Reacting Hydrocarbon Mixture With Negative Temperature Coefficient Due to the Cold-Spot and Cold Chamber Wall

AbstractAutoignition of an n-heptane/air mixture was simulated in nonuniform temperature environments of a rapid compression machine (RCM) and shock-tube (ST) with and without the presence of a cold-spot. The simulations were performed to investigate how the presence of a cold-spot and the cold boundary layer of the chamber wall may affect the ignition delay of the hydrocarbon mixture with negative temperature coefficient (NTC) behavior. The simulations were performed using three models: (1) three-dimensional (3D) computational fluid dynamics (CFD) model, (2) zero-dimensional (0D) homogenous batch reactor model by including the heat transfer model, and (3) 0D adiabatic homogenous batch reactor model. A detailed n-heptane mechanism was reduced in this work and used for 3D combustion modeling. A cold-spot critical radius of 7 mm was determined, which affects the ignition delay by more than 9%. In addition, two combustion modes were observed in the combustion chamber with a nonuniform temperature environment. With the first combustion mode, combustion starts at the high gas temperature region of the combustion chamber and quickly propagates toward the periphery of the chamber. In this combustion mode, the location of the maximum concentration of hydroxyl radical and the maximum temperature are the same. With the second combustion mode, the combustion starts at the periphery of the chamber, where the temperature is lower than the center of the chamber due to heat transfer to the cold chamber wall. The location of maximum concentration of the hydroxyl radical and maximum temperature is different with this combustion mode. The two observed combustion modes are due to the NTC behavior of the n-heptane mixture. The 0D homogenous batch reactor model (with and without heat transfer models) failed to mimic the ignition delay accurately when the second combustion mode was present. In addition, a propagating combustion has been observed in the simulation which is in agreement with some of the optical autoignition diagnostics of these hydrocarbons. This propagating combustion leads to a gradual pressure rise during autoignition, rather than a sharp pressure rise. The results of this work show that 0D homogenous batch reactor models are unable to simulate autoignition of mixtures with NTC behavior.

Laboratory study of properties of sand grouted by dual-component resins

Nowadays, technologies of chemical action on a rock mass, including the injection of polymer resins, the filling of voids by plugging with foaming compounds etc., are widely used to stabilize, to strength fractured rocks and to waterproof underground mines during development of solid minerals. In the paper we consider the issues of enhancing of the physical and mechanical properties of loose sedimentary rocks by chemical grouting with dual-component polymer resins. We perform laboratory experiments to strength fine-grained siliceous sand by the dual-component silicate-isocyanate and the foamed polyurethane resins. The grouting is performed through 10 cm diameter columns, which are filled with fine-grained siliceous sand. The main particle size fraction of the used sand is 0,150 – 0,210mm. The resin pumping into the test samples is carried out by two methods. The first method consists in sequential pumping of separate components of the polymer compounds. In this case, the solidification of the polymer compositions begins inside the rock sample. The second method consists in pumping of the fully prepared polymer compounds (two components are mixed immediately before injection in the rock sample). In this case, the solidification of the polymer compositions begins before the pumping in the rock, which leads to a rapid increase of the viscosity of the injected compositions. For both methods, the pumping is performed both with a pulse pressure increase and with a gradual (stepwise) pressure increase in the range from 0 to 15 bar. Based on the experimental results, the volume of the strengthened sand is determined. It was obtained that the volume of the strengthened (consolidated) sand is on average 2-3.5 times greater with separate-component injection, than with the injection of fully prepared compositions. For both pumping methods, a larger volume of consolidated rock is provided with a gradual (stepwise) pressure increase. Cylindrical specimens are cut out of the consolidated sand, and deformation-strength and filtration tests of the obtained material are carried out. The results show that the sequential pumping of separate components of the dual-component polymer compounds provides the greatest rock strengthening. It is obtained that the hardened sand uniaxial compressive strength is on average 1,5 times more for the sequential pumping of separate components compared to the injection of the fully prepared compositions. Similarly, the deformation modulus of hardened sand is 2,5 - 6 times more for the sequential pumping of separate components compared to the injection of the fully prepared compositions. The use of the dual-component silicate-isocyanate compositions provides more effective strengthening of loose sedimentary rocks compared to the foaming polyurethane compositions. The uniaxial compressive strength and the deformation modulus of the consolidated fine-grained sand are on average 10 - 12 times more for the dual-component silicate-isocyanate compositions compared to the foaming polyurethane compositions. The obtained data can be used to select and optimize the method of pumping of dual-component polymer compositions to stabilize disturbed mines.

Targeting innate immunity with BXCL701 in combination with pembrolizumab in patients with advanced solid cancers: Phase 2 basket study.

2558 Background: BXCL701 is an oral competitive inhibitor of dipeptidyl peptidases (DPPs), primarily DPP8/9, which triggers the inflammasome to alert and prime immune cells, leading to induction of IL-18 and IL-1ß. BXCL701 therefore, can induce an innate immune reaction and tumor inflammation, bridging between innate and adaptive immunity, potentially leading to synergistic anticancer activity when combined with PD-1 antibody pembrolizumab. Methods: This is a phase 2, open-label, single-center study (NCT04171219) of oral BXCL701 0.3 mg BID on days 1-14 and intravenous pembrolizumab 200 mg on day 1 of a 21-day cycle with a safety lead-in to evaluate RECIST/iRECIST response rate in patients with advanced solid cancers. After confirming safety and dose limiting toxicities (DLT) in the first 6 patients, additional patients are being enrolled to an immune checkpoint inhibitors (iCPI) naïve cohort and iCPI pretreated cohort. Each cohort is planned to enroll 9 patients in the first stage, and if a partial (PR) or complete response (CR) is observed the cohort is expanded to a total of 17 patients in the second stage. The treatment is considered promising if at least 3 PRs or CRs are observed in a cohort of 17 patients. Results: As of February 11, 2021, 16 patients were treated; 5 patients (prostate cancer, endometrial cancer, liposarcoma, basal cell carcinoma, squamous cell carcinoma of unknown primary) were enrolled in the iCPI naïve cohort and 11 patients (leiomyosarcoma [2], squamous cell carcinoma of unknown primary, triple negative breast cancer, uveal melanoma, melanoma, uterine myxoid sarcoma, pleomorphic sarcoma, colorectal cancer, anaplastic astrocytoma, prostate cancer) were enrolled to iCPI pretreated cohort. Among all 16 patients, there was 1 episode of grade 4 hypotension (recovered) and 1 episode of grade 5 hypotension attributed to BXCL701, which resulted in implementation of risk-mitigation strategies such as gradual dose escalation and blood pressure monitoring. In the CPI naïve cohort, of 4 patients with available imaging, 1 had a PR (microsatellite stable endometrial cancer [-62%]) and 1 durable stable disease (SD -10%, basal cell carcinoma on therapy for 6+ months). In the CPI pretreated cohort, of 9 patients with available imaging, 1 had a PR (-31%, uveal melanoma) and 3 durable SD (-22%, pleomorphic sarcoma on therapy for 8+ months; +4%, squamous cell carcinoma of unknown primary on therapy for 6 months; +5%, uterine myxoid sarcoma on therapy for 6 months). Conclusions: BXCL701 in combination with pembrolizumab demonstrated encouraging signals of activity in selected difficult-to-treat cancers. Prespecified efficacy endpoints were met in the first stage and both cohorts will proceed to second-stage of the study Clinical trial information: NCT04171219.

Exploration and practice of stress-strain evolution law of hydraulic fracturing in coal mine

In order to explore the evolution law of stress and strain in the process of hydraulic fracturing, a hollow inclusions stress-strain gauge was used for monitoring. The results show that the influence range of high-pressure water spreads to the monitoring borehole at 47m after 2 hours of hydraulic fracturing, and its influence on the stress-strain monitoring point reaches the maximum, and the strain tends to be stable in the later stage. After 6 days of hydraulic fracturing, the strain returns to a stable state without any change, but it is still larger than the state before hydraulic fracturing. During hydraulic fracturing, the increment of principal stress increases, but the amplitude is different. Hydraulic fracturing mainly affects the increment of vertical stress, which is related to the stress-strain monitoring point and the space location of the hydraulic fracturing borehole. After hydraulic fracturing, the stress increment decreases gradually and tends to return to the original stable state due to the gradual pressure relief of fracturing fluid, but it is still larger than the state without hydraulic fracturing. Hydraulic fracturing has little effect on the azimuth and dip angle of coal and rock mass. The stress-strain law can provide reference for the exploration of the coal seam permeability increasing mechanism of hydraulic fracturing.

Reduction of Vortex Formation in Mechanical Heart Valve During LV Filling

Mechanical valve implanted in mitral position has a tremendous effect on the flow dynamics in Left Ventricle (LV). The purpose of this study is to develop a new valve configuration to reduce the vortex ring formation caused by an artificial heart valve in an isovolumetric environment to generate a smoother flow field. Flow Inhibitors (FI) were built on the proximal end of the leaflet of various shapes and sizes to understand their effect on flow dynamics. The test geometries were designed based on the principles of Bernoulli’s law of fluid dynamics, pressure staging, and counter disturbance. In this research, equally spaced FI with centralized flow showed a lower and gradual pressure gradient as opposed to the control valve that was used earlier in the study done with a 27mm St. Jude mechanical valve. The pressure gradient dropped gradually from 1.4 Pa to 0.3 Pa as compared to a sudden drop in pressure in the control valve from 1.3 Pa to 0.2 Pa. The velocity value set was 0.8 m/s for simulation which dropped to 0.4 m/s in equally spaced FI centralized flow valve as compared to 0.3 m/s in the control valve. When compared on the basis of smoothness of flow field and gradual drop in the pressure, the former is weighted to be a better design. Flow inhibitor coupled with pressure staging method proved to be effective in enhancing the performance of bileaflet valve.

Global flow visualization of transonic cavity flow with various yaw angles

This study experimentally investigated transonic cavity flows with different length-to-depth ( L/ h) ratios and yaw angles. Two rectangular models with L/ h = 6.14 and 21.5 were examined with yaw angles of 10°, 30°, and 45° under a flow of Mach 0.83. The flow was visualized using pressure-sensitive paint (PSP) to obtain the detailed pressure distribution inside the cavity models. The acquired PSP data were compared with experimental data measured using Kulite transducers, and these data showed favorable agreement. Gradual pressure increases inside the cavity model with L/ h = 6.14 were observed from the PSP measurements as open cavity flow. The flow impingement at the bottom of the cavity and the significant pressure rise inside the cavity model with L/ h = 21.5 were observed as closed cavity flow. The present study quantitatively visualized the evolution of the pressure distribution from symmetric to asymmetric for different yaw angles using porous PSP sensors.

The Feasibility of Gastroesophageal Manometry for Continuously Evaluating the Degree of Expiratory Effort During Successful Crescendo Phonation

This study aimed to assess the feasibility of gastroesophageal manometry for continuously evaluating the degree of expiratory effort by measuring the pressures in the digestive tract during crescendo phonation. Each of 18 healthy nondysphonic speakers had a probe with a four-channel gastroesophageal manometer inserted through the nasal cavity to place four pressure sensors in the hypopharynx, cervical-/thoracic esophagus, and stomach, and was asked to gradually increase the vocal loudness during sustained phonation of the vowel /e:/ (vowel-crescendo task), while the sound pressure level and the pressures were simultaneously recorded. 50% of the successful vowel-crescendo task samples with a gradual and adequate sound pressure level increase showed a concomitant gradual increase in both the intra-thoracic-esophageal/intra-gastric pressure values from approximately -5 mmHg /6 mmHg to -10 mmHg/20 mmHg, respectively. The maximum pressure value was the highest in the intra-gastric pressure followed by the intra-thoracic-esophageal and intra-cervical-esophageal pressures in order. However, most of the samples showed less than one of atypical pressure changes, such as fluctuations in the intra-thoracic-esophageal and intra-gastric pressure changes and dispersion in the intra-cervical-esophageal and intra-hypopharyngeal pressure values (perhaps due to the peristaltic motions, and the contact of the sensors to the membranous wall). These results show that, during successful crescendo phonation, gastroesophageal manometry reveals a gradual increase in the intra-thoracic and intra-abdominal pressures with increasing the vocal intensity, even though showing some systematic errors, suggesting the usefulness of gastroesophageal manometry for continuously evaluating the degree of expiratory effort without influence by the laryngeal condition.

Estimation of the core degradation and relocation at the Fukushima Daiichi Nuclear Power Station Unit 2 based on RELAP/SCDAPSIM analysis

Estimation of the final debris distribution at the Fukushima Daiichi Nuclear Power Station (1F) is inevitable for a safe and effective decommissioning. It is necessary to clarify possible failure modes of the reactor pressure vessel (RPV), which is influenced by the thermal status of slumped debris that highly depends on the in-vessel accident progression. In this study, the accident analysis of 1F Unit 2 (1F2) was conducted using the RELAP/SCDAPSIM code, in order to understand better the in-vessel accident progression. One of the unsolved issues of 1F2 is the mechanism of three pressure peaks measured through late Mar. 14 to early Mar. 15, 2011. Despite various analyses, its mechanism is not clearly understood. Comparing the results of previous boiling water reactor (BWR) core degradation experiments and that of 1F2 numerical analysis, it can be estimated that most relocated metallic materials had solidified at the core bottom at the onset of first pressure peak. It is likely that the pressure increase occurred due to the evaporation of injected water reaching the heated core plate structures. Between the first and second pressure peaks, the water is assumed to have been injected continuously and the water level was likely to have recovered to BAF at the initiation of the second pressure peak. Probable slumping of a certain amount of molten materials initiated the second pressure peak and the subsequent gradual pressure increase continued possibly due to massive reaction between coolant and remaining Zircaloy in the core. Assuming the closure of the safety relief valve (SRV) at 0:00 on Mar. 15, the third pressure peak was well reproduced in the analysis. Although the total amount of the slumped material was evaluated, large deviation exists among the cases and uncertainty is still large.

Impact of Fuel Injection Distribution on Flame Holding in a Cavity-Stabilized Scramjet

This study investigated the impact of fuel injection distribution on flame stabilization and heat release in a cavity-stabilized scramjet. Experiments were conducted using a hydrogen air heater that provided vitiated air at an average stagnation temperature of 1570 K and stagnation pressure of 12.7 atm, accelerated to a Mach number of 2.2 at the combustor entrance. Ethylene was injected using two fuel injection locations, one upstream of the cavity and another in the cavity. Three different fuel injection distributions were studied for global equivalence ratios of 0.2, 0.3, and 0.4. Measurements included high-speed chemiluminescence and shadowgraph, as well as wall-mounted pressure transducers. It was found that when the cavity fuel flow rate was low, the flame stabilized on the cavity shear layer and resulted in a gradual pressure rise in the combustor. A sufficiently high fuel flow rate in the cavity led to flame stabilization upstream of the cavity, in the fuel jet wake, and a more confined combustion zone. Shadowgraph imaging showed that injection of the fuel from the cavity floor at a sufficient momentum penetrated the shear layer over the cavity and enabled flame propagation upstream of the cavity. It was concluded that the heat release distribution and pressure profile in the combustor could be significantly influenced by the fuel injection distribution through its impact on the flame stabilization mode.

Mechanisms of gradual pressure drop in angiographically normal left anterior descending and right coronary artery: Insights from wave intensity analysis

BackgroundThis study evaluated the mechanism of decline in coronary pressure from the proximal to the distal part of the coronary arteries in the left anterior descending (LAD) versus the right coronary artery (RCA) from the insight of coronary hemodynamics using wave intensity analysis (WIA). MethodsTwelve patients with angiographically normal LAD and RCA were prospectively enrolled. Distal coronary pressure, mean aortic pressure, and average peak velocity were measured at 4 different positions: 9, 6, 3, and 0 cm distal from each coronary ostium. ResultsThe distal-to-proximal coronary pressure ratio during maximum hyperemia gradually decreased in proportion to the distance from the ostium (0.92±0.03 and 0.98±0.03 at 9 cm distal to the LAD and RCA ostium). WIA showed the dominant forward-traveling compression wave gradually decreased and the backward-traveling suction wave gradually decreased in proportion to the decrease in coronary pressure through the length of the non-diseased LAD but not the RCA. ConclusionsThe pushing wave and suction wave intensities on WIA were diminished in proportion to the distance from the ostium of the LAD despite the wave intensity not changing across the length of the RCA, which may lead to gradual intracoronary pressure drop in the angiographically normal LAD.

Analysis of the Progressively Enhanced Mine Pressure in the Fully Mechanized Top Coal Caving Work Face of a 20 m Ultra-Thick Coal Seam

Considering the large mined area, wide strata moving range, strong mine pressure occurrence, and difficult roof control for the fully mechanized top coal caving in 20 m ultra-thick coal seams, this study analyzes the strata structure evolution and mine pressure occurrence behavior through field test, numerical simulation, and theoretical analysis. Based on the mine condition of the Tashan Coal Mine in the Datong mining area, mechanical models are established for the compound overlying structures. The following can be demonstrated from this study: (1) The hard strata can form three different compound spatial structures at different positions in the overlying rock strata, including the lower combined cantilever structure I, the middle combined cantilever structure II, and the upper hinged structure. (2) Failure of the higher structure can induce compression on the lower structure, which changed the break span of the lower structure. (3) “Simultaneous and nonsimultaneous structural failures” of the compound spatial structure were caused by the variation of the break span of the multilayered structure. (4) Based on the weighting characteristics, there were three stages during work face weighting, including a gradual pressure increase stage (Stage I), an accelerated pressure increase stage (Stage II), and a fast pressure increase stage (Stage III). (5) The mine pressure occurrence demonstrated a “small to medium and to large” feature. (6) Prefracturing techniques should be additionally incorporated to prevent simultaneous failure of the multilayered structure. Findings of the work can demonstrate the emergence of strong mine pressure in the Datong mining area and have theoretical significance and reference value for maintaining safe mining in similar conditions.

Gradual versus intermittent release of tourniquet in total knee arthroplasty surgery, effects on hemodynamics and acid base parameters: a prospective randomized controlled study

ABSTRACT Background Using of the pneumatic tourniquet is a common practice in many surgeries. While it creates bloodless field, it is not free of complications. Tourniquet deflation is a critical stage, greatly affecting hemodynamics. Till now, no strict guidelines have been developed for managing such a procedure. Methods Sixty patients, >40 years old, undergoing total knee arthroplasty enrolled in this study. Tourniquet deflation done over 3 min before complete release, either by gradual pressure release 50 mmHg/30 s in gradual deflation (G) group or by three cycles of deflation-reinflation (deflation for 10 s and reinflation for 50 s) in intermittent deflation (I) group. Results No significant difference was found regarding patient demographics and basal data. Mean arterial pressure was significantly lower in G group at times of deflation and post deflation for 5 min (P values 0.011, 0.023, 0.024, 0.001, and 0.013, respectively). Also, heart rate and acid base parameters were more stable and convergent to basal data in I group. Conclusion Compared to gradual deflation, intermittent deflation of tourniquet in middle and old aged, total knee arthroplasty patients resulted in more stability in hemodynamics and acid base parameters.