Pressure Limit Research Articles

Dark I-Love-Q

For neutron stars, there exist universal relations insensitive to the equation of states, the so called I-Love-Q relations, which show the connections among the moment of inertia, tidal Love number and quadrupole moment. In this paper, we show that these relations also apply to dark stars, bosonic or fermionic. The relations can be extended to higher ranges of the variables, clarifying the deviations for dark stars in the literature, as those curves all approximate the ones generated by a polytropic equation of state, when taking the low density (pressure) limit. Besides, we find that for equation of states with scaling symmetries, the I-Love-Q curves do not change when adjusting the scaling parameters.

Nurses’ Experiences at the Intensive Care Unit for COVID-19 in Indonesia: A Study of Hermeneutic Phenomenology

Background: Nurses working in Intensive Care Unit (ICU) for COVID-19 are more at risk as they interact more with infected patients. Therefore, this study aimed to explore the experience of Indonesian nurses who work in ICU for COVID-19 patients. Materials and Methods: A qualitative hermeneutic phenomenological approach was used. A total of 20 nurses working in the respective ICUs of eight COVID-19 referral tertiary hospitals in Indonesia were recruited using purposive sampling. Semistructured individual video call interviews were conducted in June–September 2021; then, Diekelmann’s hermeneutic phenomenological approach was used to analyze and interpret the data. Results: Thirteen subthemes describing the following four themes, namely, the pleasing and bad feelings, new challenges of working, nursing professional growth, and nurse resource management for COVID-19 . Conclusions: This study describes nurses’ experiences working in ICUs during the COVID-19 crisis, such as their feelings, perceived challenges, and received support. Nurse leaders play a significant role in providing adequate Personal Protective Equipment (PPE), flexible work shifts, and a caring and healing work environment. However, being aware of the limit of pressure that an individual can manage and providing adequate allowance as rewards for work in risky areas are essential to avoid burnout.

Spherical tip-plasma resonance probe with an improved upper pressure limit for electron density measurements in low-density plasmas

Spherical tip-plasma resonance probe with an improved upper pressure limit for electron density measurements in low-density plasmas

Delta Shocks and Vacuum States in the Vanishing Pressure Limit of Riemann Solutions to the Two-dimensional Steady Isentropic Flow

Delta Shocks and Vacuum States in the Vanishing Pressure Limit of Riemann Solutions to the Two-dimensional Steady Isentropic Flow

Developing a Python algorithm to calculate pressure changes during cement displacement in oilfield wells

Cementing is a crucial step when developing an oilfield well, which is usually done by pumping high-density slurry through the casing and then displacing it to the annular section. However, especially in deep structures, the whole process should be handled with increased care due to presence of excess hydrodynamic pressure. This may reach casing burst and collapse pressure limits, moreover formation fracture pressure limit in certain cases. This study introduces an algorithm, developed in Python, able to calculate dynamic pressure changes during cementing operations, and to alert when a critical pressure is reached at any point.

Seawater-corrosion-engineered CoNi electrode for highly efficient oxidation of 5-(Hydroxymethyl)furfural

The green synthesis of 2,5-furandicarboxylic acid (FDCA), famous as a bio-based polymer monomer from the 5-hydroxymethylfurfural (HMF), offers a promising route to reduce the usage of petroleum-based polymer polyethylene terephthalate. Although the electrocatalytic preparation of FDCA rids high temperature and pressure limits, most electrocatalysts used in the HMF oxidation reaction (HMFOR) are usually fabricated in harsh conditions. Therefore, we propose a method to improve the performance of electrocatalysts in the HMFOR reaction by introducing metal salts using natural seawater as the main feedstock. The final Co-sw/NF realized a 97.4% FDCA yield and 97.3% Faraday efficiency (FE). In-situ Raman techniques identified the catalytically active species of the catalysts employed in the HMFOR process. The effect of metal salts on catalyst energy levels is discussed in detail using the ultraviolet photoelectron spectroscopy (UPS) and Tauc plot method. The adsorption performance of HMF on the catalyst was determined by calculating the d-band centers and applying open circuit potential (OCP) tests. Furthermore, we elucidate the specific mechanism in terms of electron transport pathways.

Time pressure in diagnosing written clinical cases: an experimental study on time constraints and perceived time pressure.

Time pressure and time constraints have been shown to affect diagnostic accuracy, but how they interact is not clear. The current study aims to investigate the effects of both perceived time pressure (sufficient vs. insufficient time) and actual time constraints (lenient vs. restricted time limit) with regard to diagnostic accuracy. Residents from two university-affiliated trainingprograms in the USA participated in this online within-subjects experiment. They diagnosed cases under two perceived time pressure conditions: one where they were told they had sufficient time to diagnose the cases and one where they were told they had insufficient time. The actual time limit was either restricted or lenient (± one standard deviation from the mean time to diagnose). Participants provided their most likely diagnosis and a differential diagnosis for each case, and rated their confidence in their most likely diagnosis. A restricted time limit was associated with lower accuracy scores (p=0.044) but no effects of perceived time pressure on diagnostic accuracy were found. However, participants self-reported feeling more time pressure when they thought they had insufficient time (p<0.001). In addition, there was an effect of the actual time limit (p=0.012) andperceived time pressure (p=0.048) on confidence. This study showed that a restricted time limit can negatively affect diagnostic accuracy. Although participants felt more time pressure and were less confident when they thought they had insufficient time, perceived time pressure did not affect diagnostic accuracy. More research is needed to further investigate the effects of time pressure and time limits on diagnostic accuracy.

Chemical recycling of polystyrene resin and its single-used products via nitric acid oxidation: Mechanisms and effects of other plastic contaminations

Polystyrene (PS) is a widely used plastic, especially in single-use items, leading to a large accumulation of waste and serious environmental problems. A promising solution to this is an advanced recycling process to circularly use the material. In this study, the chemical recycling of PS resin (GP110) and commercial PS products via nitric acid oxidation is investigated. In addition, the effects of HDPE, PP, and PVC as contaminants in PS on the reaction mechanisms and product compositions are examined. Small-scaled reactions at 150–190 °C in a 50 mL hydrothermal autoclave revealed that GP110 is oxidized and mostly converted to benzoic acid (BA), 4-nitrobenzoic acid (4NB), and 3-nitrobenzoic acid (3NB) with a reaction time shorter than 8 h. The conversion of BA to 3NB is more favorable at high temperatures. The reactions at 170 °C for 4 h on commercial PS products, i.e., spoons, boxes, and cups, led to a much lower carbon recovery (∼24–29 %) than GP110 resin (∼42 %). A reaction time shorter than 4 h is required to reduce carbon loss, as these products are fabricated from lower molar mass PS. The oxidation of SB as a model PS waste in a larger scaled reaction, i.e., a 250 mL hydrothermal reactor, is used to assess the feasibility of applying the process for chemical recycling of PS waste. The processes (at 170 and 180 °C for 3 h) provided 53–80 % carbon recovery. The suitable ratios of solid to aqueous solution (0.23 g/mL nitric) and PS to nitric acid are in the range of ∼1/12 to 1/16 g/mL and 1/2.8 to 1/4.2 g/g, respectively, depending on the reaction conditions and the pressure limitation of the reactor. Concerning PS waste contaminated with other plastics, the results suggest that contamination with PP should be avoided in depolymerizing PS, as this can cause adverse effects, especially excessively built-up pressure in the system due to the generation of excess gaseous products.

A novel comprehensive metric balancing imaging dose and setup accuracy in image-guided radiotherapy: concept proposal and clinical validation.

To propose and validate a comprehensive novel metric balancing the registration accuracy and imaging dose for image-guided-radiotherapy based on real patient data. With written informed consent and ethical approval, 56 patients were scanned using 6MV CBCT, 140 kV CBCT, and 100 kV CBCT on Halcyon system for three consecutive treatment fractions. Online registration was performed by various on-duty therapists under routine clinical pressure and time limitation. Offline registration was carried out by an experienced physicist without pressure. The consistency between the online and offline results was used as a surrogate of the missing ground-truth of registration accuracy, which was usually developed by introducing 'known' setup errors and rescan the phantoms, yet is ethnically not applicable to real patients. The registration differences (ΔD) between various imaging methods and observers were analyzed. The weighted CT dose index (CTDIw) for kV and MV CBCT was acquired using the PTW CTDI head phantom. The weighted-Dose-Accuracy-Product (DAPw) index was defined as DAPw =ΔD(mm) w1* CTDIw(mGy) w2, where w1 and w2 are the weighting factors of accuracy and dose respectively (w1+w2=1). The mean and interquartile range (IQR) of ΔD decreased monotonically for MV CBCT, 100 kV CBCT, and 140 kV CBCT, supporting the registration consistency as a surrogate metric of image quality. Significant differences of ΔD were observed between the online and offline registration across three imaging methods (P<0.05). The 140 kV CBCT provides superior positioning accuracy, less dependency on observer subjectivity and time pressure of clinical workflow. Using w1=w2=0.5 as an example, the smallest mean, standard deviation, and IQR of DAPw were observed on the 100 kV CBCT, indicating optimal balance between dose and accuracy than the other two methods. Analysis of variance (ANOVA) showed statistically significant differences in DAPw among the different imaging methods (P<0.01, F=50.57). Using registration consistency as a surrogate indicator of image quality, this study proposed and validated a novel "DAPw" parameter based on real patient data, providing a purpose-specific tool for balancing setup accuracy and radiation dose in clinic.

Fracture caging in a lab fault to prevent seismic rupture during fluid injection

Seismic risk associated with deep fluid injection is a major holdback for geothermal energy development. Currently adopted mitigation measures include traffic light protocol and cyclic stimulation methods that retroactively limit injection pressures and flowrates based on observed seismic activity to hopefully reduce the likelihood of triggering large seismic events. Fracture caging presents an alternative proactive approach to seismicity mitigation that does not require flow rate or injection pressure limits. The caging concept is to pre-drill boundary wells around injection wells to contain all injected fluid. Prior experimental and numerical work demonstrated successful caging of tensile hydraulic fractures but did not investigate caging in shear faults. To fill this knowledge gap, this study focuses on caging of injection-induced shear fractures in a critically stressed lab-scale shear fault. Experiment variables include mechanical versus hydraulic shearing and cage size by varied well spacing. Acoustic activity was monitored using two calibrated acoustic emission systems, each having a different sensitivity bandwidth. This constitutes what we call Caged Geothermal Systems (CGS) as a modified version of Enhanced Geothermal Systems (EGS), but with CGS using more wells, an accelerated drilling timetable, much higher flow rate limits, and less proppant. We demonstrate successful caging in a lab-scale shear fault with a high recovery of the injected fluid and prevention of large critical rupture events.

Study on the effect of hydrogen cycle pressure relief time on the hydrogen permeability and mechanical properties of polyamide liner materials for type IV hydrogen storage cylinders of HFCVs

Plastic liners for type IV hydrogen storage cylinders of hydrogen fuel cell vehicles (HFCVs) experience varying pressure loads, deteriorating both hydrogen permeability and mechanical properties and impacting cylinder safety. This study performs hydrogen cycle tests on polyamide 6 (PA6) and polyamide 11 (PA11) samples (temperature: 288 K; pressure relief times: 6, 60, 3600 s; upper/lower pressure limits: 70/1 MPa). After 50 hydrogen cycles with 60 and 3600 s relief times, PA6 and PA11 exhibit changes in hydrogen permeability coefficients within 2%. However, with a 6 s relief time, the coefficients significantly decrease (>10%). After 6 s cycles, PA6 exhibits tiny holes, while PA11 exhibits clustered pieces of holes. Cracks appear in both materials' internal structures after 60 s cycles. Despite minimal tensile strength changes (within 5%), the nominal strain at tensile fracture of both materials changes significantly under different times. These findings can help determine optimal pressure relief times for hydrogen cycle tests on plastic liners.

Performance of ITER pressure gauges during deuterium operation in the large helical device

Abstract During deuterium campaigns on the heliotron large helical device (LHD), ITER pressure gauges with different cathode materials were used to measure the neutral pressure in the sub-divertor region. Throughout these campaigns, it was observed that the performance of the LaB6 cathodes was unsatisfactory, credited to the generation of neutrons impacting the gauges. Conversely, measurements taken with pressure gauges with a ZrC cathode performed well throughout the deuterium pulses. The ITER pressure gauge with the ZrC cathode could be operated with a very high electron current of 800 µA, thus improving the lower detection limit of the neutral pressure in LHD. With this design it was also possible to avoid jumps in the ion current within strong magnetic fields, improving the accuracy of the measurement from 15% uncertainty to 5%. These features allowed very precise neutral pressure measurements to be made in a fusion device with magnetic confinement. The total running time in the magnetic field was around 60 hours, less than the cathode life time of 350 hours.

Research on the Law of Low Oxygen in Working Face and Control Technology of Automatic Oxygen Spray.

Low oxygen volume fraction during the mining process of the working faces can seriously endanger the safety and health of production personnel as well as influence the normal progress of the working faces. In response to the low oxygen problem under the current prevention and control measures in the 010901 working face of Hongshiwan Coal Mine, the low oxygen factors in the working face were investigated through monitoring the gas concentration distribution status of the working face and goaf. A method of combining oxygen spraying and air guide cloth to treat low oxygen in the corner of the working face return airway was proposed in the study. Fluent simulation software was used to investigate the distribution law of the oxygen volume fraction in the corner of the working face after using air guide cloth alone and adding oxygen spraying measures. A PLC control program was designed to associate the oxygen concentration monitoring system with the oxygen spraying device, and low oxygen prevention and control technology was applied on site to obtain automatic monitoring and control of low oxygen in the working face. The research results demonstrate that under constant air flow and no oxygen injection conditions in the working face, the oxygen volume fraction in the upper corner was less than 18.5%, failing to satisfy the occupational safety and health requirements of the working face. After adding oxygen spraying measures, the oxygen spraying device was located 6.5 and 3.8 m away from the upper corner of the working face and the ground, respectively. The upper limit of the outlet pressure was set to 2.8 MPa, which can satisfy the requirements of solving low oxygen problems. With the increasing outlet pressure of the oxygen spray, there was instability in the volume fraction of oxygen in the corners of the working face. When the outlet pressure reached 1.3 MPa, the oxygen concentration in the corners of the working face increased to 20% and remained constant and the oxygen spray device automatically shuts off. Moreover, this study also provides technical support for the prevention and treatment of low oxygen in the corners of the working face.

Estimating the predictability limit of meteorological variables using permutation entropy

Understanding and quantifying the predictability of various meteorological variables remains a significant challenge in atmospheric sciences, particularly in regions with complex climates. This study aims to assess the predictability limit of wind speed, pressure, temperature, and relative humidity using permutation entropy (PermEn) analysis. By analyzing the statistical properties of PermEn values associated with each variable, our results revealed distinctive patterns of complexity and predictability. It shows clear evidence that pressure generally exhibits the lowest PermEn value, while wind speed tends to have the largest PermEn. However, the variation of PermEn values remains largely stable across different terrain conditions, which is primarily attribute to the use of daily observational data. The study also discusses the impact of window length on PermEn calculations, highlighting that longer window lengths are more likely to capture a broader range of dynamics, including more intricate and diverse temporal structures. This expanded pattern diversity leads to increased complexity of the time series, resulting in higher PermEn values. Additionally, the seasonal variation patterns of permutation entropy were found to differ among the meteorological variables considered. These findings provide valuable insight into the relative predictability of various meteorological variables, which can have important implications for atmospheric modeling, weather forecasting, and risk management.

Multi-principal element alloys for fast reactor cladding applications

Given the extensive list of multi-principal element alloys (MPEAs) within literature and the overwhelming number of alloys that can be made from only a handful of elements, this article proposes a methodology for prioritizing alloys for use as cladding within advanced reactors. This paper applies neutronic, mechanical, and chemical assessments to a collection of MPEAs available within literature for use as advanced reactor cladding. The results are compared to a reference design of HT9, a ferritic/martensitic steel, for employed in sodium-cooled fast reactor. Mechanical assessments determined pressure limits for a thin-walled tube pressure boundary, thus relating the material's mechanical properties to a minimum acceptable wall thickness. Neutronic analyses reveal a maximum allowable wall thickness that a given material must meet to provide a level of neutronic economy that is equivalent to than that of HT9. Lastly, each alloying element is compared to typical fission products found in a fast reactor fuels to mitigate deleterious phenomena such as fuel-cladding chemical interactions (FCCI). These analyses indicate that Mo-Nb-Ti-V-based alloys are likely to be advantageous and that the inclusion of elements with a high neutronic penalty (e.g., Hf) could be considered with minimal consequences.

Study on need of monitoring sound pollution at developing urban localities

Environmental pollution is a very serious issue around the world due to development of humankind towards well-being and modernization. It not only impacts health but also affects over all biodiversity. Sound does nothing till it is up to certain limit, as it creates pressure on the particles of the medium, when the limit of pressure is increased, it becomes nuisance. Sound pollution is the one important agent out of other factors that disrupts the living of humans and its ecosystem. It is related with physical, psychological or emotional states. Sound pollution adversely affects the humankind and animals leading to irritation, loss of concentration, and loss of hearing and abnormal behaviour of animals. The present work emphasizes the need to monitor and control the sound pollution in the developing cities to tackle the related future problems, to investigate the status and validity of ambient noise standards in the Indian situation, also to propose need of noise control based on the available knowledge on noise policies and regulations. The study is an approach towards importance of monitoring the sound pollution, its sources and its effects on the human activities or the ecosystem with respect to degrees of exposure in the newly developing urban localities with moderate commercial activities. The impact of sound pollution will increase if appropriate measures are not taken.

Impact of a kidney-adjusted ERAS® protocol on postoperative outcomes in patients undergoing partial nephrectomy

PurposeEvaluation of a kidney-adjusted enhanced recovery after surgery (ERAS®) protocol (kERAS) in patients undergoing nephron-sparing surgery (PN).MethodsThe kERAS protocol is a multidimensional protocol focusing on optimized perioperative fluid and nutrition management as well as strict intraoperative and postoperative blood pressure limits. It was applied in a prospective cohort (n = 147) of patients undergoing open or robotic PN. Patients were analyzed for the development of acute postoperative renal failure (AKI), achievement of TRIFECTA criteria, upstaging or new onset of chronic kidney disease (CKD) and length of hospital stay (LOS) and compared to a retrospective cohort (n = 162) without application of the protocol.ResultsCox regression analyses could not confirm a protective effect of kERAS on the development of AKI post-surgery. A positive effect was observed on TRIFECTA achievement (OR 2.2, 95% CI 1.0-4.5, p = 0.0374). Patients treated with the kERAS protocol showed less long-term CKD upstaging compared to those treated with the standard protocol (p = 0.0033). There was no significant effect on LOS and new onset of CKD.ConclusionThe implementation of a kERAS protocol can have a positive influence on long-term renal function in patients undergoing PN. It can be used safely without promoting AKI. Furthermore, it can be realized with a manageable amount of additional effort.

Analysis of the annual number of tropical cyclones over Japan using the extreme value theory

We predicted the extreme value of the annual number of typhoons, tropical cyclones over the western North Pacific, approaching typhoons, and landing typhoons for 1951–2019 over Japan and the minimum central pressure for 1987–2020 using the extreme value theory. The generalized extreme value (GEV) distribution was used to fit the extreme indices. Various diagnostic plots for assessing the accuracy of the GEV model fitted to the annual number of typhoons, approaching typhoons, and landing typhoons are shown, and all four diagnostic plots support the fitted GEV model. The shape parameter ξ for the annual number of typhoons and approaching typhoons is negative, and the number of typhoons has a finite upper limit. The calculated upper limits were 44.5 and 23.2 for the annual number of typhoons and approaching typhoons, respectively. However, ξ in the number of landing typhoons was zero; therefore, the number of landing typhoons did not have a finite upper limit, and there was a possibility that a significant risk would occur. The number of typhoons increased for 1951–2019. The minimum central pressure of typhoons estimated using geostationary satellite images decreased for 1987–2020, and the number of strong typhoons increased. The annual number of violent typhoons (≥ 54 m/s) increased in the 2010s. The calculated limit of the minimum central pressure of the typhoon is 877 hPa. When the Pacific Decadal Oscillation (PDO) index is positive, more violent typhoons tend to occur.

Ventilation practices in the neonatal intensive care units in Saudi Arabia, survey of the utilization of volume-targeted ventilation among practicing neonatologists.

To assess the current practice in using volume-targeted ventilation among neonatologists working at the Neonatal Intensive Care Units (NICU) of Saudi Arabia. The questionnaire was provided electronically to 153 practicing Neonatologists working in 39 NICUs. The survey's results were received and statistically analyzed. One hundred nineteen (119) responses were received with, a 78% response rate. Volume Targeted Ventilation (VTV) was used routinely by 67.2%, whereas 21.8% still use only pressure control (PC)/pressure limited (PL) mode. During the acute phase of ventilation support, Assist Control was the most popular synchronized mode, whereas Synchronized Intermittent Mandatory Ventilation (SIMV) with pressure support (PS) or PSV were the two most common modes during the weaning phase, 31.8%, and 31% respectively. The majority of the neonatologists used a tidal volume of 4 ml/kg as the lowest and 6 ml/kg as the highest. The major reasons for not implementing VTV were the limited availability of ventilator devices that have an option of VTV, followed by lack of experience. VTV is the predominant ventilation practice approach among neonatologists working in the KSA. Limited availability and lack of experience in using are the main challenges. Efforts to equip NICUs with the most advanced ventilation technology, enhance practitioners' experience and sufficient training in its use are warranted.

Material-Sparing Approach to Predict Tablet Capping Under Processing Compression Conditions Based on Mechanical and Molecular Properties Derived from Compaction Simulation and Crystal Structural Analysis.

Present study evaluates the usability of compaction simulation-based mechanical models as a material-sparing approach to predict tablet capping under processing compression conditions using Acetaminophen (APAP) and Ibuprofen (IBU). Measured mechanical properties were evaluated using principal component analysis (PCA) and principal component regression (PCR) models. PCR models were then utilized to predict the capping score (CS) from compression pressure (CP). APAP formulations displayed a quadratic correlation between CS and CP, with CS rank order following CP of 200MPa < 300MPa < 100MPa, indicating threshold compression pressure (TCP) limit between 200 and 300 MPa, resulting in higher CS at 300 than 200 MPa regardless of increased CP. IBU formulations displayed a linear correlation between CS and CP, with CS rank order following CP of 100MPa < 200MPa < 300MPa, indicating TCP limit between 100 and 200 MPa, resulting in higher CS at 200 and 300 than 100 MPa regardless of increased CP. Molecular models were developed as validation methods to predict capping from CP. Measured XRPD patterns of compressed tablets were linked with calculated Eatt and d-spacing of slip planes and analyzed using variable component least square methods to predict TCP triggering cleavage in slip planes and leading to capping. In APAP and IBU, TCP values were predicted at 245 and 175 MPa, meaning capped tablets above these TCP limits regardless of increased CP. A similar trend was observed in CS predictions from mechanical assessment, confirming that compaction simulation-based mechanical models can predict capping risk under desired compression conditions rapidly and accurately.