Pressure Difference Research Articles

Estimation of best geometric and operational parameters of a nanophotonics-enabled solar membrane desalination system: A numerical investigation

Nanophotonics-enabled solar membrane desalination (NESMD) system is a sustainable method to address water scarcity by desalinating seawater using solar energy. A layer of nanoparticles absorbs heat, creating localized heating within feed channel, which generates a vapor pressure difference between feed and permeate channels. Distillate water is collected in permeate channel. Numerical modelling of NESMD system, integrating optical and thermal modules in COMSOL Multiphysics, efficiently enumerates distillate flux at specified locations under varying ambient conditions. Reliability of the simulation model is confirmed through validation against in-house experimental results. A set of most effective dimensions and component specifications for NESMD system are computed that maximize distillate flux. Setup width exhibits invariant distillate flux within a range of 2–30 cm, while a feed thickness of 2 mm yields maximum distillate flux, with no change observed for permeate thickness within a range of 2–10 mm. An optimal setup length is determined within 80–200 cm range under varying operating conditions. Membrane porosity of 0.85 is selected to balance both vapor diffusivity and mechanical strength. The optimum membrane thickness lies within 180–225 µm range. An NESMD system with these best suited specifications is demonstrated to produce freshwater at the rate of 4.63 l/m2 per day.

Justification of the Locations of Differential Pressure Sensors for Coarse and Fine Filter Elements Installed one Inside the Other in a Single Gas Filter Housing

Statement of the problem. The relevant task of ensuring the uninterrupted operation of modern gas pressure reduction systems is to develop and comprehensively substantiate the possibility of using two-stage filters for natural gas purification in gas reduction points and theoretically substantiate the method for calculating the pressure drop in cylindrical filter elements (CFE). Results. It is proved that when gas flows in the upper cross section of the filter, the pressure drop will be less than in lower cross sections, including the pressure drop in the lowest cross section. This leads to a larger amount of leaking gas, to a larger mass of impurities settling in the lower part of the filter elements of cylindrical coarse and fine cleaning and to a greater degree of their clogging. Therefore, it is recommended to place gas pressure sensors in the lower part of the internal volume of the coarse and fine-cleaned CFE, so that the flow direction of the coarse and finely purified gas washing the sensors at the location of the hole for measuring statistical pressure is tangential to the side surface of the sensor tube. Then the flow direction of the roughly and finely purified gas entering the holes of the sensors is carried out at an angle of 90° and the pressure gauges measure the static pressure. Conclusions. The locations of pressure drop sensors on coarse and fine filter elements installed one inside the other in a single gas filter housing are substantiated. The proposed arrangement of differential pressure sensors will significantly increase the possibility of receiving an earlier signal about the degree of clogging of the gas filter at the control room, as well as have a significant amount of time for timely removal of blockages formed in the coarse cleaning CFE and replacement of fine cleaning CFE.

Prevalence of interarm blood pressure difference is notably higher in women; the Viborg population-based screening program (VISP)

BackgroundBilateral blood pressure (BP) measurement is important in cardiovascular prevention for identifying systolic interarm BP difference (IAD) and hypertension. We investigated sex-stratified IAD prevalence and its associations and coexistence with screen-detected peripheral atherosclerosis and hypertension. Furthermore, we determined the proportion misclassified as non-hypertensive when using the lower versus the higher reading arm.MethodsThis sub-study formed part of the Viborg Screening Program (VISP), a cross-sectorial population-based cardiovascular screening programme targeting 67-year-old Danes. VISP includes screening for peripheral atherosclerosis (lower extremity arterial disease and carotid plaque), abdominal aortic aneurysm, hypertension, diabetes mellitus, and cardiac disease. Self-reported comorbidities, risk factors, and medication use were also collected. Among 4,602 attendees, 4,517 (82.1%) had eligible bilateral and repeated BP measurements. IAD was defined as a systolic BP difference ≥ 10 mmHg. IAD-associated factors (screening results and risk factors) were estimated by logistic regression; proportional coexistence was displayed by Venn diagrams (screening results).ResultsWe included 2,220 women (49.2%) and 2,297 men (50.8%). IAD was more predominant in women (26.8%) than men (21.0%) (p < 0.001). This disparity persisted after adjustment [odds ratio (OR) 1.53; 95% confidence interval (CI) 1.32–1.77]. No other association was recorded with the conditions screened for, barring potential hypertension: BP 140–159/90–99 mmHg (OR 1.68, 95% CI 1.44–1.97) and BP ≥ 160/100 mmHg (OR 1.82, 95% CI 1.49–2.23). Overall, IAD and BP ≥ 160/100 mmHg coexistence was 4% in women and 5% in men; for BP ≥ 140/90 mmHg, 13% and 14%, respectively. Among those recording a mean BP ≥ 140/90 mmHg in the higher reading arm, 14.5% of women and 15.3% of men would be misclassified as non-hypertensive compared with the lowest reading arm.ConclusionFemale sex was an independent factor of IAD prevalence but not associated with other arterial lesions. Approximately 15% needed reclassification according to BP ≥ 140/90 mmHg when the lower rather than the higher reading arm was used; verifying bilateral BP measurements improved detection of potential hypertension. In future, the predictive value of sex-stratified IAD should be assessed for cardiovascular events and death to verify its potential as a screening tool in population-based cardiovascular screening.Trial registration for VISPNCT03395509:10/12/2018.

Experimental investigation of a transcritical CO2 refrigeration system incorporating rotary gas pressure exchanger and low lift ejectors

Natural refrigerants like CO2 are playing a significant role in making refrigeration and heat pump systems climate-friendly by slowly phasing out the high global warming refrigerants like hydrofluorocarbons (HFCs). However, the efficiency of a transcritical CO2 refrigeration system declines significantly when the ambient temperature increases, primarily attributed to the high-pressure lift and the losses incurred during expansion. To remedy this issue, this paper presents a novel rotary gas pressure exchanger (PXG) device, which simultaneously achieves high differential pressure expansion work recovery and the “free compression” of the portion of the flash gas in a compact, rotary machine. For this, a PXG device is designed, fabricated, and tested to achieve free compression of CO2 over the entire differential pressure of approximately 70 bar between a receiver and a gas cooler. This is one of the highest free-pressure lift provided by any device to date in CO2 refrigeration. However, there is a small pressure loss of approximately 1–2 bar in the system due to viscous and inertia losses in the piping and in the PXG itself, which needs to be overcome by an external booster device. Results on a baseline PXG integrated system with two low lift booster compressors are presented, which show up to 60 bar free pressure lift and up to 18.2 % COP improvement provided by PXG. Additionally, key performance characteristics of the PXG, like the expansion work recovery, the mass boost ratio, direct fluid-to-fluid contact, and no pass-through operation are experimentally quantified. This work also presents a novel method to integrate two low lift ejectors with PXG to eliminate the need for separate low lift compressors. The low lift ejectors are designed, fabricated, and tested in-house, followed by their integration with the PXG device. A new type of transcritical CO2 refrigeration system is designed to integrate these low lift ejectors with PXG, and experiments are conducted at various evaporator thermal duties and gas cooler exit temperatures, simulating varying ambient temperature conditions. A novel control system to control the gas cooler pressure to optimal thermodynamic levels using PXG rotational speed is demonstrated experimentally. Further, automated control of high-pressure low lift ejector mass flow using an in-built needle design has been successfully demonstrated to optimise PXG mass boost performance. The LP low lift ejector achieved a successful pressure lift of 3.8 bar, and the HP low lift ejector showed a lift of 5.7 bar on the top of 42 bar free pressure lift provided by PXG for up to 5.8 kg/min mass flow delivered by free PXG compression. The results from this study demonstrate that the PXG device provides a significant energy efficiency improvement to the transcritical CO2 refrigeration system, and the novel low lift ejectors, when integrated with PXG, provide a successful method to maximise PXG’s thermodynamic potential.

The effects of a digital lifestyle intervention in patients with hypertension: Results of a pilot randomized controlled trial.

In this pilot study, the authors investigated the preliminary effectiveness of the digital lifestyle intervention, actensio (mementor DE GmbH), in treating arterial hypertension. Adults with arterial hypertension were randomly assigned to an intervention group (actensio+standard care) or a control group (waiting list+standard care) in a 1:1 ratio. Primary and secondary endpoints were assessed at baseline (t0) and 3months post-randomization (t1). The primary endpoint was average systolic blood pressure, measured at home for 1week. Secondary endpoints included patient engagement (measured using the "patient activation measure"; PAM-13), average diastolic blood pressure, and heart rate. All endpoints were analyzed using ANCOVA models, following an intention-to-treat approach, while adjusting for baseline values. Missing data were estimated using multiple imputation models. A total of N=102 participants (f=59, age=52.94±9.01) were randomized to either the intervention (IG; N=52) or the control group (CG; N=50), of which N=80 completed the blood pressure diary, and N=81 the PAM-13 at t1. Between-group comparisons showed an average group difference in systolic blood pressure of -5.06mm Hg (95% CI=-8.71 to -1.41, p=.013) between the intervention group (M=137.37±10.13) and the control group (M=142.35±11.23). Average group difference for patient engagement was 3.35 points with a trend towards statistical significance (95% CI=-018 to 6.89, p=.064), favoring the intervention group (MIG=79.38±9.44vs. MCG=75.45±10.62). There were no group differences in diastolic blood pressure (-1.78mm Hg; 95% CI=-4.50 to 0.95, p=.402) and heart rate (-0.684; 95% CI=-3.73 to 2.36, p=0.683). The results of the present pilot study confirm the preliminary effectiveness of the digital lifestyle intervention, actensio, in reducing high blood pressure in patients with hypertension.

Three-pressure prediction method of jointing well-seismic data in JT1 well area of Sichuan Basin in China

With the high yield of many wells represented by Well JT1 in the Maokou Formation, has catalyzed a surge in exploration activities along the platform margin facies of the Maokou Formation in central Sichuan and further showed the significant exploration potential of the Maokou Formation in the northern slope. However, the fracture cave body of the Maokou Formation exhibits a high degree of development, strong longitudinal and horizontal heterogeneity, large formation pressure differences, and drilling events such as gas kicks and lost circulation occur frequently, which seriously affects the efficient implementation of drilling. Understanding the spatial distribution of the three-pressure in the formation can help better deal with and solve the above problems. Therefore, in order to help the safe, high-quality and rapid drilling of the Maokou Formation in the study area, and enhance the efficiency of oil and gas development, this paper explores the research on the prediction method of the three-pressure of jointing well-seismic data based on the geomechanical experimental data and the actual drilling data. In the process of prediction of pore pressure, this study found that the pore pressure and formation velocity in the study area have an exponential relationship. In order to enhance the applicability of the Filippone’s method in the study area and improve the prediction accuracy of pore pressure, the linear relationship between pore pressure and formation velocity in the Filippone’s method is modified to an exponential relationship, and a pore pressure prediction model suitable for the work area was established. Based on the Mohr–Coulomb criterion and Huang's model, the prediction models of collapse pressure and fracture pressure applicable to the study area were established, respectively. Then, the elastic parameters were obtained through pre-stack inversion, and the three-pressure bodies were calculated based on the elastic parameter bodies. The results indicate that: (1) The three-pressure prediction method of the jointing well-seismic data in this paper can predict the formation's longitudinal and transverse pressure anomaly zones in advance. (2) The Maokou Formation in the study area is characterized by abnormally high pressure, to balance the pressure of the high-ground formation, high-density drilling fluid is necessary. (3) The prediction results of three-pressure in this paper are highly consistent with the actual drilling engineering events, which verifies the reliability of the three-pressure prediction results presented in this study. The results of the study can provide a basis for decision-making in drilling geological design, such as the determination of drilling fluid density, the evaluation of borehole stability and other engineering problems that require support from three-pressure data.

Investigation on the coupling damage effects of ships subjected to near-field underwater explosion loads

Near-field underwater explosions generate complex load forms and cause destructive strikes on ships. To investigate the damage characteristics of ships under the combined effect of multiple loads, local and overall damage modes were first investigated through the combination of experimental tests and numerical simulation. Then a series of numerical simulations of full-scale ships subjected to near-field underwater explosions with different stand-off distances, equivalents, and detonation positions were carried out. The damage effects of shock wave, bubble pulsation, after flow, and water jet loads on ships were analyzed. The results show that the combined effects of different loads lead to different damage modes. Shock waves and after flow loads are the main cause of local damage and hogging damage, while pressure difference and bubble adsorption are the main reasons for the hogging damage. Finally, a criterion was proposed to determine the damage modes of ships under near-field underwater explosions.

Measurement of Air-Water Counter-Current Flow Rates in Vertical Annulus Using Multiple Differential Pressure Signals and Machine Learning

Abstract Gas-liquid counter-current flow in vertical annulus is involved in multiple industrial fields such as petroleum engineering. For instance, in coalbed methane wells where liquid pumping is utilized, obtaining real-time gas-liquid flow in the annulus is crucial for the development and management of coalbed methane wells. However, due to complex flow conditions, this requirement is difficult to achieve through traditional flow measurement means. Therefore, this paper proposes a flow prediction method based on multiple sets of differential pressure signals and machine learning techniques. Experiments on air-water two-phase flow were conducted on a vertical annulus pipe with an inner/outer diameter of 75mm/125mm and adjustable eccentricity. The probability density function and power spectral density function of three sets of differential pressure signals collected at different heights in the annulus pipe were used as model inputs, and gas-liquid flow rate as output. A gas-liquid two-phase flow prediction model was constructed based on the artificial neural network model, and the hyper-parameters of the model were optimized using Bayesian optimization. The results show that on a test dataset of 440 combinations of conditions with air superficial velocity of 0.06~5.04m/s, water superficial velocity of 0.03~0.25m/s, and pipe eccentricity of 0, 0.25, 0.5, 0.75, 1, the model can achieve average prediction errors of 9.12% and 29.34% for gas and water flow, respectively. This indicates that the method can be applied to non-throttling, non-intrusive measurement of phase flow under annulus gas-liquid counter-current flow conditions.

Kinetic study of the reaction of thiophene-tocopherols with peroxyl radicals enlightenings the role of O˙⋯S noncovalent interactions in H-atom transfer.

Three new α-tocopherol thiophene derivatives were efficiently synthesized, characterized and used for the first time as chain-breaking antioxidants for the inhibition of the autoxidation of reference oxidizable substrates. The rate constant of the reaction with alkylperoxyl (ROO˙) radicals and the stoichiometry of radical trapping (n) for the thiophene-tocopherol compounds were determined by measuring the oxygen consumption during the autoxidation of styrene or isopropylbenzene, using a differential pressure transducer. The measurement of the reaction with ROO˙ radicals in an apolar solvent at 30 °C showed inhibition rate constants (kinh) in the order of 104 M-1 s-1. To rationalise the kinetic results, the effect of the thiophene ring on the H-atom donation by O-H groups of the functionalized tocopherols was investigated by theoretical calculations. The importance of noncovalent interactions (including an unusual O˙⋯S bond) for the stability of the conformers has been shown, and the O-H bond dissociation enthalpy (BDE(OH)) of these derivatives was determined. Finally, the photophysical properties of these new compounds were investigated to understand if the addition of thiophene groups changes the absorption or emission spectra of the tocopherol skeleton for their possible application as luminescent molecular probes.

Measurement of Air-Water Counter-Current Flow Rates in Vertical Annulus Using Multiple Differential Pressure Signals and Machine Learning

Measurement of Air-Water Counter-Current Flow Rates in Vertical Annulus Using Multiple Differential Pressure Signals and Machine Learning

Energy loss analysis in two-stage turbine of compressed air energy storage system: Effect of varying partial admission ratio and inlet pressure

The compressed air energy storage (CAES) system experiences decreasing air storage pressure during energy release process. To ensure system stability, maintaining a specific pressure difference between air storage and turbine inlet is necessary. Hence, adopting a judicious air distribution scheme for the turbine is crucial. Partial admission, based on reasoned nozzle governing methods, enhances system performance. This investigation explores the impact of varying partial admission ratio (PAR) and inlet pressure on flow dynamics and loss characteristics under rated output power. Full circumferential numerical simulations of a two-stage axial turbine within CAES system elucidates insights. First-stage efficiency declines linearly with decreasing PAR, while second-stage displays escalating reductions. Principally, turbine energy losses primarily stem from the entropy production rate (EPR) by turbulent dissipation and EPR arising from heat transfer with fluctuating temperature gradients. Partial admission significantly affects losses within the rotor, especially within the second stage. Leaving velocity loss for 50 % PAR is about 3 times that of 100 % PAR. The percentage of losses within R2 for 50 % PAR increases by 6.7 % compared with that for 100 % PAR. This research provides theoretical insights for designing, regulating, and optimizing nozzle governing and partial admission turbines in CAES systems.

Visualization experiment on the ignition performance and flame-spreading in different charging structures

In order to investigate the influence of different charging structures on the ignition performance and its influence on the particle movement before and after the film rupture of the chamber, a visualization experiment platform of the chamber was designed and built, and the stage tests of the ignition of the full particle charging, partial particle charging, mixed before and after the rod-particle charging and the full rod charging were carried out. The experiment shows that the free space will cause the flame propagation speed to increase significantly, from 77 m/s in the charge area to 575 m/s, and there will be pressure fluctuations in several areas of the chamber. The ignition performance of the rod is obviously better than that of the granular, and the pressure fluctuation in the chamber is smaller, the peak ignition gas pressure in the rod charge structure is only 50 % of that in the granular charge structure (1.6 MPa:3.2 MPa), and the maximum pressure difference is only 20 % of that in the granular propellant structure (0.5 MPa:2.5 MPa). The rod-particle mixed charge bed has good ignition consistency in the rod charge area, and when it reaches the granular charge area, the flame will be significantly hindered. The rod basically stays still during the ignition process in the chamber, while the granular will move with the gas flow when there is free space, and after the film is broken, the particle movement is faster than that before the film is broken.

Effect of Hydrophobic Dust Particles on the Evaporation Rate from Water Surface

In the paper, the effect of natural dust deposited from the air on the evaporation rate from the water surface is experimentally investigated. Experiments were conducted for stationary liquid without wind blowing across the surface and with mild wind that does not deform the surface, at a constant rate of particle deposition. It is shown that the evaporation rate is a linear function of the difference in the saturated vapor pressure at the water surface and the partial pressure of the air mixture at the temperature and relative humidity in the laboratory at the beginning of the deposition process, when the proportion of the surface covered with dust is small. With the increase in deposition time, hydrophobic particles gather into conglomerates, reducing the proportion of the exposed surface and the evaporation rate.

Mixed convective flow analysis of a Maxwell fluid with double diffusion theory on a vertically exponentially stretching surface

It observers that an object is submerged in a liquid, more pressure is applied to its bottom surface than its top surface, as a result pressure rises within depth of fluids. A buoyancy force is generated due to the pressure difference. In the current investigation, the mathematical formulation of bio-convective stagnation point flow of a radiative Maxwell fluid with multiple slip effect on an exponentially porous stretching surface is analyzed thoroughly. The buoyancy assisting and opposing conditions with magnetic field are discussed in the current investigation. Moreover, the energy and concertation equations are formulated by the utilization of Cattaneo–Christov theory and non-uniform heat source/sink. The flow model is developed in the form of partial derivatives, then use the similarity variables to convert the physical system into nonlinear ordinary derivative. The nonlinear system is tackled numerically with the help of Bvp4c approach on the MATLAB. The graphical upshots for various emerging parameter are observed with two aspects: buoyancy assisting λ>0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\left( {\\lambda > 0} \\right)$$\\end{document} and buoyancy opposing λ<0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\left( {\\lambda < 0} \\right)$$\\end{document}. The observation shows that the greater values of mixed convection parameter improves the fluid velocity for assisting flow λ>0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\left( {\\lambda > 0} \\right)$$\\end{document}, while declining trend is noticing for opposing flow situation λ>0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\left( {\\lambda > 0} \\right)$$\\end{document}. Further, it is worth noticing that stronger inputs of thermal and concentration relaxation parameter yield lesser thermal and concentration diffusivity, which reduces the temperature and nanoparticles concentration.

Mixed convective flow analysis of a Maxwell fluid with double diffusion theory on a vertically exponentially stretching surface

It observers that an object is submerged in a liquid, more pressure is applied to its bottom surface than its top surface, as a result pressure rises within depth of fluids. A buoyancy force is generated due to the pressure difference. In the current investigation, the mathematical formulation of bio-convective stagnation point flow of a radiative Maxwell fluid with multiple slip effect on an exponentially porous stretching surface is analyzed thoroughly. The buoyancy assisting and opposing conditions with magnetic field are discussed in the current investigation. Moreover, the energy and concertation equations are formulated by the utilization of Cattaneo–Christov theory and non-uniform heat source/sink. The flow model is developed in the form of partial derivatives, then use the similarity variables to convert the physical system into nonlinear ordinary derivative. The nonlinear system is tackled numerically with the help of Bvp4c approach on the MATLAB. The graphical upshots for various emerging parameter are observed with two aspects: buoyancy assisting λ>0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\left( {\\lambda > 0} \\right)$$\\end{document} and buoyancy opposing λ<0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\left( {\\lambda < 0} \\right)$$\\end{document}. The observation shows that the greater values of mixed convection parameter improves the fluid velocity for assisting flow λ>0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\left( {\\lambda > 0} \\right)$$\\end{document}, while declining trend is noticing for opposing flow situation λ>0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\left( {\\lambda > 0} \\right)$$\\end{document}. Further, it is worth noticing that stronger inputs of thermal and concentration relaxation parameter yield lesser thermal and concentration diffusivity, which reduces the temperature and nanoparticles concentration.

Association between early pregnancy maternal blood pressure and risk of congenital heart disease in offspring

Objective: To analyze the association between maternal blood pressure and congenital heart disease (CHD) in offspring. Methods: From February 2018 to December 2020, pregnant women who participated in the China birth cohort study in Beijing Obstetrics and Gynecology Hospital, Shenzhen Maternal and Child Healthcare Hospital and Chengdu Women's and Children's Central Hospital were enrolled in this study. The baseline and follow-up information were collected using an electronic data collection system. Stepwise logistic regression model was used to analyze the association between maternal blood pressure including systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP) and pulse pressure difference (PP) in the first trimester of pregnancy and the risk of CHD in the offspring. A restrictive cubic spline curve was used to draw the dose-response curve between maternal blood pressure and CHD. Results: A total of 55 552 participants were included in this study. Of them, 31 038, 15 375 and 9 139 pregnant women were enrolled in Beijing Obstetrics and Gynecology Hospital, Shenzhen Maternal & Child Healthcare Hospital and Chendu Women's and Children's Central Hospital, respecitively. The age of pregnant women was (31.3±4.0) and the incidence of CHD in the offspring was 0.78% (435/55 552). Multivariable logistic regression model analysis showed that the increase of SBP (OR=1.01, 95%CI: 1.00-1.02), DBP (OR=1.01, 95%CI: 1.00-1.03) and MAP (OR=1.02, 95%CI: 1.00-1.03) in the first trimester were significantly associated with the risk of CHD in the offspring. The restrictive cubic spline analysis showed a positive linear association of SBP (Ptotal<0.001; Pnon-liear=0.315), DBP (Ptotal<0.001; Pnon-liear=0.928) and MAP (Ptotal<0.001; Pnon-liear=0.929) with the risk of CHD in the offspring. Conclusion: Maternal SBP, DBP and MAP in the first trimester of pregnancy were positively associated with the risk of CHD in the offspring.

Effect of Fentanyl Compared to Morphine on Pain Score and Cardiorespiratory Vital Signs in Out-of-Hospital Adult STEMI Patients

Objective: ST-elevation myocardial infarction (STEMI) is a leading cause of mortality in Australia. Paramedics treating adults with STEMI in the out-of-hospital environment can use fentanyl or morphine to manage the patient’s pain, although there is little research comparing the efficacy and safety of these drugs. Therefore, the objective of this study was to compare the effects of fentanyl to morphine on cardiac chest pain and cardiorespiratory vital signs in adult STEMI patients in the out-of-hospital environment. Methods: We conducted a retrospective analysis of records of 1902 STEMI cases attended by Queensland Ambulance Service paramedics during the 4-year interval from 2013 to 2016. We compared pain score, blood pressure, respiratory rate, and pulse rate between patients administered intravenous fentanyl and intravenous morphine. We used a two-way mixed effects model (drug, time) to assess for main and interaction effects, and where the interaction effect was significant, applied Mann-Whitney U tests to further analyze between-group differences at each time point. Results: We observed a significant main effect of time on pain score (p &lt; 0.001), respiratory rate (p &lt; 0.05), and pulse rate (p = 0.025), such that these variables all decreased over time. Additionally, we observed a significant drug-time interaction for systolic and diastolic blood pressures (both p &lt; 0.01), such that blood pressures decreased over time in the morphine, but not fentanyl, group. Conclusion: We compared the effects of fentanyl to morphine on cardiac chest pain and cardiorespiratory vital signs in out-of-hospital adult STEMI patients and observed differences in blood pressures only. Morphine appeared to have a depressive effect on systolic and diastolic blood pressure, whereas fentanyl did not. An unanticipated behavioural finding of this research is that, in the absence of a definitive guideline, paramedics appear to use fentanyl when patients may be at risk of developing hypotension.

Inertia from radiation. A semiclassical approach

Abstract Starting from a thought experiment based on an accelerated reflecting cavity that contains a radiation bath, is evaluated the cavity-radiation dynamical interaction. The radiation is considered as a monochromatic flux of photons that bouncing onward and backward in the direction of acceleration. For this case, in each reflection, the delay originated by the time of flight of photons causes a difference of velocity between the receiving and emitting reflecting faces in the opposite ends of cavity, and consequently, a Doppler shift. Despite to the ends of the cavity are at rest relative to each other, this phenomenon generates a difference of radiation pressure between these, that behave as the inertia of the radiation bath and verifies the Newton’s 2nd Law for non-relativistic conditions. This result has interesting implications on the current theoretical pictures of dynamical properties of photons.

Design and dynamic characterization of a phototunable optofluidic lens

Optofluidic devices that dynamically respond to light stimuli have the potential to impart modern adaptive optics with intrinsic optical logic without the need for external power sources or feedback control. While photo actuation is typically associated with low energy efficiency compared with alternative modes of actuation, fluid lenses can be tuned with minimal work by generating small differential pressures across the surface of the lens to drive a change in focal length. In this study, we developed a wide aperture (9.5 mm) photothermally actuated lens that leverages spatially and thermodynamically informed design principles developed for resistively heated thermo-pneumatically actuated lenses. Using experimentally validated models to describe the curvature of pressurized elastomer-bound interfaces, we demonstrated phototunable modulation of the focal length from 124 mm to 90 mm in real time using 233 mW of 405 nm light over 30 s of irradiation with an estimated 8.2 µJ of mechanical work (10−4% efficiency). The initial focal length recovered after 60 s in the dark over three consecutive cycles of actuation. Additionally, the photoactuated response is shown to correlate well with the light intensity.

Flow and heat transfer performance of reciprocating oscillatory flow in a Stirling engine compared to steady unidirectional flow

The driving force of a Stirling engine comes from the thermal expansion and cold compression of working gas under reciprocating oscillating flow, the flow and heat transfer performance of which is significantly different with that of steady state unidirectional flow. In this work, the performance differences in a heating tube for a Stirling engine under steady state unidirectional and reciprocating oscillating flows were studied. The results indicate that the temperature distribution was mainly dependent on the inlet velocity for a steady unidirectional flow. For a reciprocating oscillatory flow, the temperature distribution was greatly affected by the working gas state in the previous period besides the inlet velocity. Furthermore, a slightly weaker of heat transfer was obtained for reciprocating oscillatory flow, accompanying with a slightly stronger pressure consumption. The change time of pressure difference, velocity and heat transfer for the reciprocating oscillatory flow were earlier than, substantially equal to, and later than that of the steady unidirectional flow. Finally, the entry-return asymmetric insert was suggested to prioritize the heat transfer enhancement in entry process of a heating tube under reciprocating oscillatory flow to achieve the excellent overall performance for a Stirling engine.