Low Pressure Research Articles

Outcomes of extremely preterm infants who participated in a randomised trial of dopamine for treatment of hypotension (the HIP trial) at 2 years corrected age

ObjectiveTo determine survival and neurodevelopmental outcomes in the Hypotension in Preterm (HIP) trial.DesignProspective follow-up of infants enrolled in randomised controlled trial.Participants58 infants born before 28 weeks of gestation with low...

Fluid Resuscitation and Initial Management in Patients Presenting with Sepsis in the General Ward.

The optimal management of hospital-presenting sepsis remains poorly understood. We investigated the initial management in patients presenting with sepsis in the general ward, the association between fluid resuscitation and clinical outcomes, and the factors affecting fluid resuscitation. A retrospective study was conducted on patients who presented with sepsis-induced hypotension in the general ward. Patients were divided into Less 30 (fluid resuscitation less than 30 mL/kg) and More 30 (fluid resuscitation 30 mL/kg or more) groups. Multivariable logistic regression analysis was performed. The median resuscitation fluid volume was 500 mL (9.2 mL/kg) and 2000 mL (35.9 mL/kg) in the Less 30 (n = 79) and More 30 (n = 11) groups, respectively. The intensive care unit (ICU) mortality was similar between the two groups (43.0% vs. 45.5%). Twenty-two patients received continuous renal replacement therapy (CRRT) in the Less 30 group, whereas none received it in the More 30 group (27.8% vs. 0%). Fluid resuscitation ≥30 mL/kg was not associated with ICU mortality. Low body weight and systolic blood pressure were associated with fluid resuscitation ≥30 mL/kg. Most hospital-presenting sepsis patients received less than 30 mL/kg of fluid, and fluid resuscitation was not associated with ICU mortality.

Parametric assessment of size and peak pressure variability for cavitation bubbles induced by low-voltage discharge

Abstract Cavitation presents a significant challenge in the operation and longevity of hydraulic machinery. Studying a single cavitation bubble can provide fundamental insights into the phenomenon. One simple and popular method to generate such bubbles is through a low-voltage discharge between two contacting electrodes to create a spark that locally vaporizes water. This study investigates the repeatability of this method in generating consistent bubbles. The electrode length is one parameter that influences the bubble size. However, the excess length (the electrode length after the contact point) is shown to be the primary variable influencing the bubble size rather than the total electrode length. Additionally, even for bubbles of similar size, significant variability in wall pressure peaks was observed for bubbles generated far from the surface. This variability correlates with the time the electrodes require to melt and break. Longer melting times are associated with extended bubble lifetimes and lower pressure peaks.

Biomass Burning Plumes From Indochina Toward Southern China: Predominant Synoptic Weather Processes and Interactions

AbstractEvery spring, biomass burning (BB) plumes from the Indochina Peninsula (ICP) are transported downstream by specific synoptic weather processes, potentially influencing regional weather through radiative effects of BB aerosols. However, the favorable weather patterns for transport toward inland China and how they interact with BB aerosols are not fully understood. In this study, we identified three predominant synoptic weather processes associated with evident BB plume transport toward southern China over the past 20 years. The first two—the low pressure over the continent and the cold frontal passage—account for more than 76% of all the events. In low‐pressure events accompanied by surface warming, a cyclonic system hovers over southern China, with southerly winds favoring the northward movement of BB plumes throughout the lower troposphere. The second type is caused by a frontal passage lasting only 1–2 days, which lifts BB plumes to above 700 hPa and transports them downstream. To further explore aerosol feedback on different weather patterns, we conducted WRF‐Chem simulations and found an average of 2°C cooling near the surface, along with 1.5°C warming in the lower troposphere over the southern coast of East Asia. Consequently, the more stable atmosphere suppresses the low‐pressure system but enhances the cold frontal system. Meanwhile, anomalous circulations from aerosol radiative effects align with those during the frontal passage, boosting plume transport with a 45% (20%) rise in CO (BC) along the transport belt toward inland southern China. This work highlights the importance of considering the interactions between wildfire pollutants and different weather processes.

Resilience of Chlorella vulgaris to Simulated Atmospheric Gas Compositions of Mars, Jupiter, and Titan.

This study investigates the resilience of the unicellular green microalga Chlorella vulgaris to extreme atmospheric conditions simulating those of Mars, Jupiter, and Titan. Using Earth as a control, experiments were conducted under autotrophic and mixotrophic conditions to evaluate the organism's photosynthetic efficiency, oxygen production, and biomass growth over 2, 5, and 12 days. Photosynthetic performance was analyzed through chlorophyll a fluorescence induction (JIP-test), metabolic activity via gas chromatography, and biomass accumulation measurements. Despite the extreme atmospheric compositions-ranging from the CO2-rich, low-pressure Martian atmosphere to the anoxic atmospheres of Jupiter and Titan-C. vulgaris demonstrated resilience and a functional photosynthetic apparatus, maintaining growth and oxygen production. Notably, the Martian atmosphere enhanced photosynthetic performance, with fluorescence curves and Fv/Fm ratios surpassing Earth-like conditions, likely due to elevated CO2 and low pressure. Under mixotrophic conditions, the addition of glucose further enhanced metabolic activity and biomass growth across all atmospheres. These findings highlight the potential of C. vulgaris for bioregenerative life support systems, enabling oxygen production, CO2 sequestration, and resource cultivation in extraterrestrial habitats. The study showcases the organism's adaptability to extreme environments, with implications for astrobiology, space exploration, and sustainable extraterrestrial ecosystems. These findings expand habitability criteria and explore extremophiles' potential to support life beyond Earth.

Vibron Softening of Solid Hydrogen under Nanoconfinement.

The vibron behavior of hydrogen bears significant importance for understanding the phases of solid hydrogen under high pressure. In this work, we reveal an unusual high-pressure behavior of hydrogen confined within nanopores through a combination of experimental measurements and theoretical calculations. The nanoconfined hydrogen molecules retain an hcp lattice up to 170 GPa, yet significant deviations from the vibrational characteristics of bulk hydrogen are observed in the primary vibrons of both Raman and infrared spectra. This lowered vibron peak is linked to the disorder of the hydrogen molecules with longer bonds and enhanced intermolecular interactions at the interface. Further investigation reveals that this nanoscale confinement leads to a considerable decrease in the band gap of solid hydrogen, potentially facilitating band gap closure at considerably lower pressures. Our findings provide crucial insights into the behavior of solid hydrogen under spatial nanoconfinement, paving the way for novel explorations into hydrogen metallization.

Dual Regulation of Ionic Effect on Zostera marina L. Seed Germination and Leaf Differentiation in Low-Salinity Conditions.

Low-salinity conditions are generally used in land-based cultivation to promote the germination and growth of Zostera marina L. and to improve the restoration effect of seagrass beds. Different salinity conditions lead to morphological and physiological differences. To investigate the impacts of salinity and osmotic pressure on the germination and early development of Zostera marina seeds, this study utilized seawater with different salinity conditions and PEG-6000 solutions to simulate various non-ionic osmotic pressures and examine the germination, cotyledon growth, and leaf differentiation over 28 days, as well as determine the biochemical traits on days 1, 3, 5, and 7. The results show that the cumulative germination rate in LS-0 was 91.6%, but it was not significantly affected by the PEG solutions. The different salinities (5, 10, and 15) had no significant effect on the germination rate, which ranged from 76.4% to 78.8%: low salinity and low osmotic pressure stimulated the germination by accelerating the water uptake through increased osmotic pressure differences. The leaf differentiation was regulated by the osmotic pressure and salinity. In LS-10, the most used condition, the leaf differentiation rate was 35.2%, while PEG-10 displayed 6.4%. The total soluble sugar and soluble protein in the seeds decreased. Antioxidant enzyme activities were activated under low-salinity conditions, which supported germination within a tolerable oxidative stress range.

Real time monitoring of intrarenal pressures while using the flexible and navigable suction ureteral access sheath.

To report on in-vivo intrarenal pressure (IRP) during flexible ureteroscopy for treatment of kidney stones while using the novel flexible and navigable suction ureteral access sheath (FANS). A retrospective observational analysis was performed for 25 patients undergoing routine flexible ureteroscopy for treatment of renal stones between February 2024 and June 2024 from two centres in Canada. The LithoVue Elite™ ureteroscope (Boston Scientific Corp., Marlborough, MA, USA) with pressure sensing capability was used together with the Clearpetra® Ureteral Access Sheath System (Well Lead Medical Co. Ltd., Guangzhou, China) for all cases. Irrigation was via a pressure bag set at 250mmHg where possible and the access sheath was connected to wall suction at 200mmHg. Median and maximum IRP, as well as the distribution of cumulative procedure times according to various IRP ranges were analyzed. The median age of the patients was 56 years, with a median BMI of 26.7kg/m2. The median (Interquartile range {IQR}) IRP for all the cases was 22.0 (15.0-36.5) mmHg, with a median (IQR) procedure time of 35.9 (16.4-54.8) minutes. The IRP remained below 40mmHg in 76.2% of the total time in all procedures, and was below 60mmHg in 94.1% of the time. Significant variables associated with lower IRP were having a prior endourological procedure, pre-stenting, larger ureteral access sheath size and use of pre-operative alpha blocker. Age, BMI and total stone volume did not significantly affect IRP. Low intrarenal pressures can be achieved with the use of FANS, even with higher irrigation pressures. Alpha blocker use, larger sheath size, prior endourological procedures and pre-stenting are all associated with lower IRP.

Lactobacillus-Loaded Easily Injectable Hydrogel Promotes Endometrial Repair via Long-Term Retention and Microenvironment Modulation.

Regeneration of the injured endometrium, particularly the functional layer, is crucial for the prevention of uterine infertility. At present, clinical treatment using sodium hyaluronate hydrogel injection is limited by its relatively low fluidity, short-term retention, and insufficient bioactive ingredients, so it is necessary to develop an advanced healing-promoting hydrogel. The modulation of the microenvironment by Lactobacillus presents a bioactive component that can facilitate the regeneration of the functional layer. Our study introduces a multifunctional Lactobacillus-loaded poly(N-isopropylacrylamide)-grafted bacterial cellulose (BC-g-PN@L) hydrogel designed with superior injectability and in situ stability. At 25 °C (room temperature), a uniform distribution is achieved with a low injection pressure of only 7.90 kPa. At 37 °C (body temperature), the BC-g-PN@L hydrogel forms a robust three-dimensional nanonetwork, providing space and substance exchange channels for Lactobacillus to maintain its viability and bioactivity. Enhanced by the hydrophobic isopropyl groups in poly(N-isopropylacrylamide) side chains and the rigid bacterial cellulose substrates, the BC-g-PN@L hydrogel exhibits prolonged retention properties in the uterine cavity, persisting for over 21 days. These attributes endow the BC-g-PN@L hydrogel with versatile pro-healing capacity and microenvironment modulation in a rat model of endometrial injury. Our BC-g-PN@L hydrogel promotes the development of advanced injectable hydrogels to facilitate both histological and functional repair of the injured endometrium.

Artificial Intelligence Chatbot and Low CSF Pressure Headaches Decision-Making

Background The potential for inaccuracy while using AI could cause problems for future doctors attempting to pass their board exams, doctors attempting to brush up on a certain topic in a short amount of time, or those trying to make use of AI to for patient care decision-making. Low CSF pressure headaches can be highly disabling for patients and are often misdiagnosed These types of headaches are relatively common, effecting approximately 5 individuals per 100,000 per year. Methods An AI model was selected to examine the neurological scenario through a Neurology expert’s guidance to determine a diagnosis. While some AI models are more developed than others, a free, heavily utilized platform was used in this testing. Results the AI gave direction to order an MRI and consult with other Neurological doctors, but it failed to arrive at the correct differential diagnosis. In the test, the first failure was to request the appropriate tests. It then failed to provide an accurate working diagnosis. Discussion Without understanding an AI model’s limitations, it may lead to negative patient outcomes if used in medical decision-making. This could also prolong the patient’s condition, allowing them to suffer unnecessary pain and potential disability.

Unboxing: Exploring the Challenges of Green Supply Chain Initiatives in Thailand

Background: The increasing global focus on sustainability has made Green Supply Chain Management (GSCM) a critical strategy for businesses to balance environmental responsibility with operational efficiency. Despite its benefits, GSCM adoption in developing countries faces significant challenges. This study addresses the gap by investigating these barriers within the Thai context, providing actionable insights for policymakers and businesses. Methods: A mixed-methods approach was employed, including a survey of 480 business owners, executives, and supply chain employees, and expert analysis using Interpretive Structural Modeling (ISM). The ISM technique was used to determine the relationships and hierarchy among key barriers to GSCM implementation. Results: The findings reveal that weak legal frameworks, insufficient supplier engagement, and a lack of social responsibility are the most significant barriers. Secondary factors, such as low consumer demand and minimal competitive pressure, exacerbate these challenges. The ISM analysis highlighted the cascading effects of foundational barriers on other dimensions of GSCM adoption. Conclusions: Strengthening environmental regulations, promoting supplier collaboration, and embedding sustainability in corporate culture are key to overcoming GSCM barriers to sustainably enhance Thailand’s competitiveness.

Medical Problems of Chronic Hypoxia in Highlanders Living on the Tibetan Plateau.

Ri-Li Ge. Medical problems of chronic hypoxia in highlanders living on the tibetan plateau. High Alt Med Biol. 00:00-00, 2024.-Health issues at high altitudes arise due to the lower atmospheric pressure and subsequent reduction in the partial pressure of oxygen in ambient air. While much research has been published on health problems of lowlanders who move to high altitudes, less is known about the medical challenges faced by long-term and permanent high-altitude residents, especially in the Qinghai-Tibetan plateau. In this review, we briefly summarized the chronic hypoxia-related health issues in highlanders, focusing on the specific population of the Qinghai-Tibetan plateau. It deals with important health problems for highlanders, including the main disease categories, from chronic mountain sicknesses and pulmonary hypertension (PH) to kidney, neurocognitive impairments, perinatal problems, and congenital heart defect. However, the most hallmark of disorders is excessive erythrocytosis associated with specific symptoms and signs, and high-altitude heart disease is characterized by excessive PH, right ventricular hypertrophy, and right heart failure. We also provide information on potential treatment strategies, including some traditional Tibetan medical practices and also a combination of Western medicine and traditional Chinese medicine to prevent and treat these conditions effectively. This mini-review is heavily based on a couple of decades of research carried out by Chinese high-altitude medical research groups at the Qinghai-Tibetan Plateau. We believe that this review will provide valuable perspective to researchers whose study interest and base lie in high altitude.

Eastward propagation of mid-latitude near-surface thermohaline anomaly and link to marine heat waves in the eastern North Pacific

Eastward propagations of near-surface and isopycnal thermohaline disturbances at 25.5–26.3σθ with a zonal speed of in-situ geostrophic current were observed in the mid-latitude (40–50° N) North Pacific and were linked to the marine heat wave (MHW) ‘The Blob’ in the Gulf of Alaska (GOA: 150–130° W and 40–50° N). Isopycnal depth anomalies were formed corresponding to wind-stress curl anomalies and propagated eastward. A warm and low-salinity disturbance was formed in the central Pacific in 2011–2012 under the negative maximum of Pacific Decadal Oscillation (PDO). This warm, low-salinity and low-density disturbance propagated eastward and was warmed by heating anomaly of surface heat flux, reduced entrainment and northward heat advection in 2013 due to the weakened westerly wind. The disturbance propagated further eastward and reached the GOA in early 2014. During the 2014–2015 MHW, heating by reduced entrainment and horizontal heat advection maintained the MHW, even though surface heat flux worked as cooling anomaly. The reduced entrainment was caused by the enhanced density stratification of the warm and low-density surface water, together with the entrainment of warm-saline subsurface water which was formed in 2013 in the area west of the GOA and subducted and propagated eastward as subsurface isopycnal warm-saline anomaly. Pycnocline heaving due to wind-induced upwelling corresponding to the strengthened Aleutian Low Pressure under the 2014–2015 El-Niño contributed to the stratification enhancement. The heating of the horizontal heat advection was due to weakened westerly wind on the northern side of strengthened and southward-shifted Aleutian Low Pressure under the El-Niño and positive PDO.

Phytic Acid-Induced Gradient Hydrogels for Highly Sensitive and Broad Range Pressure Sensing.

Ionic conductive hydrogels have emerged as an excellent option for constructing dielectric layers of interfacial iontronic sensors. Among these, gradient ionic hydrogels, due to the intrinsic gradient elastic modulus, can achieve a wide range of pressure responses. However, the fabrication of gradient hydrogels with optimal mechanical and sensing properties remains a challenge. In this study, it is discovered first that phytic acid (PA) interacts in remarkably distinct manners (i.e., plasticizing effects and phase separation) with different polymers (i.e., polyacrylamide and polyacrylic acid). This distinctive PA-polymer interacting mechanism is innovatively utilized to construct a modulus gradient ionic hydrogel through a simple precursor solution infiltration approach. The gradient hydrogel-based flexible pressure sensor not only achieves a high sensitivity (9.00kPa-1, <15kPa) and a broad sensing range (from ≈3.7Pa to 1.2MPa) simultaneously, but also exhibits superior low pressure sensing performance. It successfully recognizes the subtle pressure due to acoustic waves and airflow, as well as the moderate pressure due to speaking and finger pressing and the high magnitude of plantar pressure. In addition, the gradient hydrogel demonstrates remarkable antibacterial properties and biocompatibility. This functional hydrogel with excellent sensing performance and bioactivity exhibits exceptional potential for wearable sensing applications.

Short-term impact of low air pressure on plants' functional traits.

Lower atmospheric pressure affects biologically relevant physical parameters such as gas partial pressure and concentration, leading to increased water vapor diffusivity and greater soil water content loss through evapotranspiration. This might impact plant photosynthetic activity, resource allocation, water relations, and growth. However, the direct impact of low air pressure on plant physiology is largely unknown. This study examined the effects of low air pressure, alone and combined with two water inputs, on different functional traits of three plant species transplanted from montane grasslands at 1,500 m a.s.l. during the first four weeks of their early phenological stage: Trifolium pratense, Hieracium pilosella, and Brachypodium rupestre. Using the terraXcube Ecotron facility which can simulate different climatic conditions, we isolated the effect of air pressure from those of other, related environmental factors (temperature, humidity, and solar radiation) by simulating three different elevations with corresponding air pressures: 1,500 m a.s.l. (85 kPa, control scenario), 2,500 m a.s.l. (75 kPa), and 4,000 m a.s.l. (62 kPa) and we used two different water regimes to observe the combined effect of low air pressure and the impact of varying water inputs on plants. In T. pratense and H. pilosella, we observed an increase in stomatal conductance but a reduction in aboveground biomass at the lowest pressure compared to the control scenario after four weeks of incubation. Contrastingly, B. rupestre showed an interactive effect of air pressure and water treatment on chlorophyll and biomass nitrogen content, which were reduced under higher soil water conditions at 85kPa. This study serves as an initial step in isolating the specific impact of air pressure on plant physiology, demonstrating the potential of the facility for future research. The mixed response patterns across species highlight that atmospheric pressure could be a driving factor to consider when assessing plant responses along elevational gradient.

Design of High-Temperature Superconducting Ternary Hydride NaY3H20 at Moderate Pressure via Introducing Hydrogen Vacancies.

Superconducting hydrides exhibiting a high critical temperature (Tc) under extreme pressures have garnered significant interest. However, the extremely high pressures required for their stability have limited their practical applications. The current challenge is to identify high-Tc superconducting hydrides that can be stabilized at lower or even ambient pressures. Here, we propose a strategy for designing high-Tc superconducting hydrides at low pressures by introducing defects into the hydrogen frameworks of clathrate hydrides. We present a type of hydrogen-vacancy structural type AB3H20 derived from type-I clathrate hydrides and identified a stable NaY3H20 through high-throughput calculations. Further calculations show that NaY3H20 is thermodynamically stable above 133 GPa and dynamically stable down to 20 GPa, with a predicted high Tc of approximately 115 K. It significantly reduces the pressure required for stability compared to that of type-I clathrate hydrides with high Tc. Our results provide a foundation for further exploration of high-Tc superconducting hydrides at lower pressures or even ambient conditions.

Rheological Behavior of Gassy Marine Clay: Coupling Effects of Bubbles and Salinity

Understanding the rheological behavior of marine clay is crucial to analyzing submarine landslides and their impact on marine resource exploitation. Dispersed bubbles in marine clay (gassy clay) and electrolytes in seawater (e.g., NaCl concentration of 0.47 M) significantly impacts rheological properties. Under low ionic strength and low pore water pressure conditions, dispersed bubbles have a strengthening effect on the yield stress and the viscosity of clays. This effect turns into a weakening effect when the pore water pressure reaches 300 kPa or the ionic strength exceeds 0.18 M. It was proposed that the effect of bubbles, whether strengthening or weakening, was determined by the size of bubbles with respect to the characteristic size of the particle structure formed by clay particles. A theoretical model was developed, which reasonably captures rheological behaviors of gassy clays.

Tele-mentorship versus in-person mentorship for trainee performance of cricothyroidotomy

Introduction Physicians and other first-line medical care providers may find themselves in an airway management emergency where they cannot ventilate, cannot oxygenate, and have limited resources to aid them. The rise in use of tele-health and other virtual interfaces creates the opportunity to bring experienced guidance to a resource-poor critical airway situation. We aimed to compare in-person mentoring (IPM) by an emergency medicine (EM) physician to tele-mentoring (TM) by a trauma surgeon for an emergent surgical airway. Methods Thirty EM residents were randomized to cricothyroidotomy on a model with IPM or TM. The IPM preceptor was an EM attending, and TM preceptors were trauma surgeons. The procedure was timed and graded on a Global Rating Scale (GRS). Post-procedure, mentor and trainee completed a NASA Task Load Index (TLX). Results There was no difference in procedure success; however, the IPM group took longer (163.6 vs. 107.6 s, p &lt; 0.05). TM trainees experienced greater temporal demand (4.27 vs. 2.73, p = 0.03). Telementors recorded improved performance compared to in-person mentors (2.30 vs. 4.17, p &lt; 0.05). Comparing mentors and trainees in each arm, IPM trainees felt more temporal demand than their mentors (4.63 vs. 2.73, p &lt; 0.05) while TM trainees felt they had worse performance than their mentors perceived (4.23 vs. 2.3, p = 0.01). Discussion Performance based on GRS between groups was equal; however, those with telementors secured the airway more rapidly. Telementors reported higher performance and lower time pressure than in-person preceptors. This data suggests that TM is effective for precepting cricothyroidotomy and may be the superior option in some settings.

A Prospective Study on the Role of Serial Estimation of Lower Limb Compartmental Pressure as Diagnostic and Monitoring Tool in Compartment Syndrome

A Prospective Study on the Role of Serial Estimation of Lower Limb Compartmental Pressure as Diagnostic and Monitoring Tool in Compartment Syndrome

Passivating Lattice Oxygen in ZnO Nanocrystals to Reduce its Interactions with the Key Intermediates for a Selective Photocatalytic Methane Oxidation to Methanol

An inevitable overoxidation process is considered as one of the most challenging problems in the direct conversion of methane (CH4) to methanol (CH3OH), which is limited by the uncontrollable cracking of key intermediates. Herein, we have successfully constructed a photocatalyst, the Fe‐doped ZnO hollow polyhedron (Fe/ZnOHP), for the highly selective photoconversion of CH4 to CH3OH under mild conditions. In‐situ experiments and density functional theory calculations confirmed that the introduction of Fe was able to decrease the energy level of the O 2p orbital, which passivated the activity of lattice oxygen in ZnO nanocrystals. This passivation effect greatly weakened the interaction between *CH3 and lattice oxygen, thus facilitating the conversion of *CH3O to *CH3 intermediate rather than the direct desorption of *CH3O. As a result, Fe/ZnOHP exhibited excellent CH3OH generation rate (ca. 1009 μmol gcat−1 h‐1) and selectivity (ca. 96%) in the photocatalytic conversion of CH4 at room temperature and low pressure.