Effect of positive end-expiratory pressure ventilation on central venous pressure and intraoperative blood loss in patients undergoing laparoscopic hepatectomy

Objective:Tto investigate the effects of positive end-expiratory pressure(PEEP)ventilation on central venous pressure(CVP)and intraoperative blood loss in patients undergoing laparoscopic hepatectomy.Methods:46 cases of patients undergoing laparoscopic hepatectomy,25 cases of male,female 21 cases,ASAⅠ~Ⅲlevel,were randomly divided into two groups.In group A tidal volume was set to 6 ml/kg(Predicted Body Weight,PBW)and PEEP was set to 0 cmH2O.The tidal volume of group B was set as group A,PEEP was set to 8 cmH2O.CVP,MAP,and Ppeak were recorded in the supine position after intubation(T0),supine position after pneumoperitoneal(T1),anti-trendelenberg position after pneumoperitoneal(T2),supine position after surgery(T3),and Ddyn was calculated.The amount of nitroglycerin and the amount of blood loss were recorded.Results:Compared with group A,the CVP of group B was significantly increased at T1 and T2(P<0.05).Compared to T2 with T1 in group A and group B,CVP was decreased significantly(P<0.05).At T3,Cdyn in group B was significantly higher than that in group A(P<0.05).The amount of nitroglycerin in group B was significantly higher than that in group A(P<0.05).There was no significant difference in intraoperative fluid rehydration and blood loss between the two groups(P>0.05).Conclusion:PEEP with 8cmH2O can improve Ddyn in patients undergoing laparoscopic hepatectomy,but increased CVP.It requires more use of controlled low central venous pressure techniques to reduce intraoperative blood loss.

Role of proning and positive end-expiratory pressure in COVID-19

The novel coronavirus,which was declared a pandemic by the World Health Organization in early 2020 has brought with itself major morbidity and mortality.It has increased hospital occupancy,heralded economic turmoil,and the rapid transmission and community spread have added to the burden of the virus.Most of the patients are admitted to the intensive care unit(ICU)for acute hypoxic respiratory failure often secondary to acute respiratory distress syndrome(ARDS).Based on the limited data available,there have been different opinions about the respiratory mechanics of the ARDS caused by coronavirus disease 2019(COVID-19).Our article provides an insight into COVID-19 pathophysiology and how it differs from typical ARDS.Based on these differences,our article explains the different approach to ventilation in COVID-19 ARDS compared to typical ARDS.We critically analyze the role of positive end-expiratory pressure(PEEP)and proning in the ICU patients.Through the limited data and clinical experience are available,we believe that early proning in COVID-19 patients improves oxygenation and optimal PEEP should be titrated based on individual lung compliance.

Effects of positive end-expiratory pressure on intracranial pressure,cerebral perfusion pressure,and brain oxygenation in acute brain injury:Friend or foe?A scoping review

Background Patients with acute brain injury(ABI)are a peculiar population because ABI does not only affect the brain but also other organs such as the lungs,as theorized in brain–lung crosstalk models.ABI patients often require mechanical ventilation(MV)to avoid the complications of impaired respiratory function that can follow ABI;MV should be settled with meticulousness owing to its effects on the intracranial compartment,especially regarding positive end-expiratory pressure(PEEP).This scoping review aimed to(1)describe the physiological basis and mechanisms related to the effects of PEEP in ABI;(2)examine how clinical research is conducted on this topic;(3)identify methods for setting PEEP in ABI;and(4)investigate the impact of the application of PEEP in ABI on the outcome.Methods The five-stage paradigm devised by Peters et al.and expanded by Arksey and O'Malley,Levac et al.,and the Joanna Briggs Institute was used for methodology.We also adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses(PRISMA)extension criteria.Inclusion criteria:we compiled all scientific data from peer-reviewed journals and studies that discussed the application of PEEP and its impact on intracranial pressure,cerebral perfusion pressure,and brain oxygenation in adult patients with ABI.Exclusion criteria:studies that only examined a pediatric patient group(those under the age of 18),experiments conducted solely on animals;studies without intracranial pressure and/or cerebral perfusion pressure determinations,and studies with incomplete information.Two authors searched and screened for inclusion in papers published up to July 2023 using the PubMed-indexed online database.Data were presented in narrative and tubular form.Results The initial search yielded 330 references on the application of PEEP in ABI,of which 36 met our inclusion criteria.PEEP has recognized beneficial effects on gas exchange,but it produces hemodynamic changes that should be predicted to avoid undesired consequences on cerebral blood flow and intracranial pressure.Moreover,the elastic properties of the lungs influence the transmission of the forces applied by MV over the brain so they should be taken into consideration.Currently,there are no specific tools that can predict the effect of PEEP on the brain,but there is an established need for a comprehensive monitoring approach for these patients,acknowledging the etiology of ABI and the measurable variables to personalize MV.Conclusion PEEP can be safely used in patients with ABI to improve gas exchange keeping in mind its potentially harmful effects,which can be predicted with adequate monitoring supported by bedside non-invasive neuromonitoring tools.

Driving pressure in mechanical ventilation:A review

Driving pressure(ΔP)is a core therapeutic component of mechanical ventilation(MV).Varying levels ofΔP have been employed during MV depending on the type of underlying pathology and severity of injury.However,ΔP levels have also been shown to closely impact hard endpoints such as mortality.Considering this,conducting an in-depth review ofΔP as a unique,outcome-impacting therapeutic modality is extremely important.There is a need to understand the subtleties involved in making sureΔP levels are optimized to enhance outcomes and minimize harm.We performed this narrative review to further explore the various uses ofΔP,the different parameters that can affect its use,and how outcomes vary in different patient populations at different pressure levels.To better utilizeΔP in MV-requiring patients,additional large-scale clinical studies are needed.

Influence of positive end-expiratory pressure upregulation on the right ventricle in critical patients with acute respiratory distress syndrome:an observational cohort study

Background This study aimed to investigate the influence of positive end-expiratory pressure(PEEP)on the right ventricle(RV)of mechanical ventilation-assisted patients through echocardiography.Methods Seventy-six patients assisted with mechanical ventilation were enrolled in this study.Positive end-expiratory pressure was upregulated by 4 cm H_(2)O to treat acute respiratory distress syndrome,wherein echocardiography was performed before and after this process.Hemodynamic data were also recorded.All variables were compared before and after PEEP upregulation.The effect of PEEP was also evaluated in patients with and without decreased static lung compliance(SLC).Results Positive end-expiratory pressure upregulation significantly affected the RV function.Remarkable differences were observed in the following:Tei index(P=0.027),pulmonary artery pressure(P=0.039),tricuspid annular plane systolic excursion(P=0.014),early wave/atrial wave(P=0.002),diaphragm excursion(P<0.001),inferior vena cava collapsing index(P<0.001),and SLC(P<0.001).There were no significant changes in heart rate,respiratory rate,central venous pressure,mean arterial pressure,and base excess(P>0.05).Furthermore,the cardiac output of the RV was not significantly affected.In patients with decreased SLC(n=41),there were more significant changes in diaphragm excursion(P<0.001),inferior vena cava collapse index(P=0.025),pulmonary artery pressure(P<0.001),and tricuspid annular plane systolic excursion(P=0.007)than in those without decreased SLC(n=35).Conclusion Positive end-expiratory pressure upregulation significantly affected the RV function of critically ill patients with acute respiratory distress syndrome,especially in those with decreased SLC.

A personalized electronic textile for ultrasensitive pressure sensing enabled by biocompatible MXene/ PEDOT:PSS composite

Flexible,breathable,and highly sensitive pressure sensors have increasingly become a focal point of interest due to their pivotal role in healthcare monitoring,advanced electronic skin applications,and disease diagnosis.However,traditional methods,involving elastomer film-based substrates or encapsulation techniques,often fall short due to mechanical mismatches,discomfort,lack of breathability,and limitations in sensing abilities.Consequently,there is a pressing need,yet it remains a significant challenge to create pressure sensors that are not only highly breathable,flexible,and comfortable but also sensitive,durable,and biocompatible.Herein,we present a biocompatible and breathable fabric-based pressure sensor,using nonwoven fabrics as both the sensing electrode(coated with MXene/poly(3,4-ethylenedioxythiophene):polystyrene sulfonate[PEDOT:PSS])and the interdigitated electrode(printed with MXene pattern)via a scalable spray-coating and screen-coating technique.The resultant device exhibits commendable air permeability,biocompatibility,and pressure sensing performance,including a remarkable sensitivity(754.5 kPa^(−1)),rapid response/recovery time(180/110 ms),and robust cycling stability.Furthermore,the integration of PEDOT:PSS plays a crucial role in protecting the MXene nanosheets from oxidation,significantly enhancing the device's long-term durability.These outstanding features make this sensor highly suitable for applications in fullrange human activities detection and disease diagnosis.Our study underscores the promising future of flexible pressure sensors in the realm of intelligent wearable electronics,setting a new benchmark for the industry.

Mechanical Performance of Bio-inspired Bidirectional Corrugated Sandwich Pressure Shell Under External Hydrostatic Pressure

This paper aims to enhance the compression capacity of underwater cylindrical shells by adopting the corrugated sandwich structure of cuttlebone.The cuttlebone suffers uniaxial external compression,while underwater cylindrical shells are in a biaxial compressive stress state.To suit the biaxial compressive stress state,a novel bidirectional corrugated sandwich structure is proposed to improve the bearing capacity of cylindrical shells.The static and buckling analysis for the sandwich shell and the unstiffened cylindrical shell with the same volume-weight ratio are studied by numerical simulation.It is indicated that the proposed sandwich shell can effectively reduce the ratio between circumferential and axial stress from 2 to 1.25 and improve the critical buckling load by about 1.63 times.Numerical simulation shows that optimizing and adjusting the structural parameters could significantly improve the advantage of the sandwich shell.Then,the hydrostatic pressure tests for shell models fabricated by 3D printing are carried out.According to the experimental results,the overall failure position of the sandwich shell is at the center part of the sandwich shell.It has been found the average critical load of the proposed sandwich shell models exceeds two times that of the unstiffened shell models.Hence,the proposed bio-inspired bidirectional corrugated sandwich structure can significantly enhance the pressure resistance capability of cylindrical shells.

How Does Stacking Pressure Affect the Performance of Solid Electrolytes and All-Solid-State Lithium Metal Batteries?

All-solid-state lithium metal batteries(ASSLMBs)with solid electrolytes(SEs)have emerged as a promising alternative to liquid electrolyte-based Li-ion batteries due to their higher energy density and safety.However,since ASSLMBs lack the wetting properties of liquid electrolytes,they require stacking pressure to prevent contact loss between electrodes and SEs.Though previous studies showed that stacking pressure could impact certain performance aspects,a comprehensive investigation into the effects of stacking pressure has not been conducted.To address this gap,we utilized the Li_(6)PS_(5)Cl solid electrolyte as a reference and investigated the effects of stacking pressures on the performance of SEs and ASSLMBs.We also developed models to explain the underlying origin of these effects and predict battery performance,such as ionic conductivity and critical current density.Our results demonstrated that an appropriate stacking pressure is necessary to achieve optimal performance,and each step of applying pressure requires a specific pressure value.These findings can help explain discrepancies in the literature and provide guidance to establish standardized testing conditions and reporting benchmarks for ASSLMBs.Overall,this study contributes to the understanding of the impact of stacking pressure on the performance of ASSLMBs and highlights the importance of careful pressure optimization for optimal battery performance.

Effects of seepage pressure on the mechanical behaviors and microstructure of sandstone

Surrounding rocks of underground engineering are subjected to long-term seepage pressure,which can deteriorate the mechanical properties and cause serious disasters.In order to understand the impact of seepage pressure on the mechanical property of sandstone,uniaxial compression tests,P-wave velocity measurements,and nuclear magnetic resonance(NMR)tests were conducted on saturated sandstone samples with varied seepage pressures(i.e.0 MPa,3 MPa,4 MPa,5 MPa,6 MPa,7 MPa).The results demonstrate that the mechanical parameters(uniaxial compressive strength,peak strain,elastic modulus,and brittleness index),total energy,elastic strain energy,as well as elastic strain energy ratio,decrease with increasing seepage pressure,while the dissipation energy and dissipation energy ratio increase.Moreover,as seepage pressure increases,the micro-pores gradually transform into meso-pores and macro-pores.This increases the cumulative porosity of sandstone and decreases P-wave velocity.The numerical results indicate that as seepage pressure rises,the number of tensile cracks increases progressively,the angle range of microcracks is basically from 50-120to 80-100,and as a result,the failure mode transforms to the tensile-shear mixed failure mode.Finally,the effects of seepage pressure on mechanical properties were discussed.The results show that decrease in the effective stress and cohesion under the action of seepage pressure could lead to deterioration of strength behaviors of sandstone.

Emulsifying property,antioxidant activity,and bitterness of soybean protein isolate hydrolysate obtained by Corolase PP under high hydrostatic pressure

Enzymatic hydrolysis of proteins can enhance their emulsifying properties and antioxidant activities.However,the problem related to the hydrolysis of proteins was the generation of the bitter taste.Recently,high hydrostatic pressure(HHP)treatment has attracted much interest and has been used in several studies on protein modification.Hence,the study aimed to investigate the effects of enzymatic hydrolysis by Corolase PP under different pressure treatments(0.1,100,200,and 300 MPa for 1-5 h at 50℃)on the emulsifying property,antioxidant activity,and bitterness of soybean protein isolate hydrolysate(SPIH).As observed,the hydrolysate obtained at 200 MPa for 4 h had the highest emulsifying activity index(47.49 m^(2)/g)and emulsifying stability index(92.98%),and it had higher antioxidant activities(44.77%DPPH free radical scavenging activity,31.12%superoxide anion radical scavenging activity,and 61.50%copper ion chelating activity).At the same time,the enhancement of emulsion stability was related to the increase of zeta potential and the decrease of mean particle size.In addition,the hydrolysate obtained at 200 MPa for 4 h had a lower bitterness value and showed better palatability.This study has a broad application prospect in developing food ingredients and healthy foods.

Reservoir quality evaluation of the Narimba Formation in Bass Basin,Australia:Implications from petrophysical analysis,sedimentological features,capillary pressure and wetting fluid saturation

The evaluation of reservoir quality was accomplished on the Late Paleocene to Early Eocene Narimba Formation in Bass Basin,Australia.This study involved combination methods such as petrophysical analysis,petrography and sedimentological studies,reservoir quality and fluid flow units from derivative parameters,and capillary pressure and wetting fluid saturation relationship.Textural and diagenetic features are affecting the reservoir quality.Cementation,compaction,and presence of clay minerals such as kaolinite are found to reduce the quality while dissolution and secondary porosity are noticed to improve it.It is believed that the Narimba Formation is a potential reservoir with a wide range of porosity and permeability.Porosity ranges from 3.1%to 25.4%with a mean of 15.84%,while permeability ranges between 0.01 mD and 510 mD,with a mean of 31.05 mD.Based on the heterogenous lithology,the formation has been categorized into five groups based on permeability variations.Group I showed an excellent to good quality reservoir with coarse grains.The impacts of both textural and diagenetic features improve the reservoir and producing higher reservoir quality index(RQI)and flow zone indicators(FZI)as well as mostly mega pores.The non-wetting fluid migration has the higher possibility to flow in the formation while displacement pressure recorded as zero.Group II showed a fair quality reservoir with lower petrophysical properties in macro pores.The irreducible water saturation is increasing while the textural and digenetic properties are still enhancing the reservoir quality.Group III reflects lower quality reservoir with mostly macro pores and higher displacement pressure.It may indicate smaller grain size and increasing amount of cement and clay minerals.Group IV,and V are interpreted as a poor-quality reservoir that has lower RQI and FZI.The textural and digenetic features are negatively affecting the reservoir and are leading to smaller pore size and pore throat radii(r35)values to be within the range of macro,meso-,micro-,and nano pores.The capillary displacement pressure curves of the three groups show increases reaching the maximum value of 400 psia in group V.Agreement with the classification of permeability,r35 values,and pore type can be used in identifying the quality of reservoir.

An adaptive physics-informed deep learning method for pore pressure prediction using seismic data

Accurate prediction of formation pore pressure is essential to predict fluid flow and manage hydrocarbon production in petroleum engineering.Recent deep learning technique has been receiving more interest due to the great potential to deal with pore pressure prediction.However,most of the traditional deep learning models are less efficient to address generalization problems.To fill this technical gap,in this work,we developed a new adaptive physics-informed deep learning model with high generalization capability to predict pore pressure values directly from seismic data.Specifically,the new model,named CGP-NN,consists of a novel parametric features extraction approach(1DCPP),a stacked multilayer gated recurrent model(multilayer GRU),and an adaptive physics-informed loss function.Through machine training,the developed model can automatically select the optimal physical model to constrain the results for each pore pressure prediction.The CGP-NN model has the best generalization when the physicsrelated metricλ=0.5.A hybrid approach combining Eaton and Bowers methods is also proposed to build machine-learnable labels for solving the problem of few labels.To validate the developed model and methodology,a case study on a complex reservoir in Tarim Basin was further performed to demonstrate the high accuracy on the pore pressure prediction of new wells along with the strong generalization ability.The adaptive physics-informed deep learning approach presented here has potential application in the prediction of pore pressures coupled with multiple genesis mechanisms using seismic data.

The regulation of ferrocene-based catalysts on heat transfer in highpressure combustion of ammonium perchlorate/hydroxyl-terminated polybutadiene/aluminum composite propellants

The regulation of the burning rate pressure exponent for the ammonium perchlorate/hydroxylterminated polybutadiene/aluminum(AP/HTPB/Al)composite propellants under high pressures is a crucial step for its application in high-pressure solid rocket motors.In this work,the combustion characteristics of AP/HTPB/Al composite propellants containing ferrocene-based catalysts were investigated,including the burning rate,thermal behavior,the local heat transfer,and temperature profile in the range of 7-28 MPa.The results showed that the exponent breaks were still observed in the propellants after the addition of positive catalysts(Ce-Fc-MOF),the burning rate inhibitor((Ferrocenylmethyl)trimethylammonium bromide,Fc Br)and the mixture of Fc Br/catocene(GFP).However,the characteristic pressure has increased,and the exponent decreased from 1.14 to 0.66,0.55,and 0.48 when the addition of Ce-FcMOF,Fc Br and Fc Br/GFP in the propellants.In addition,the temperature in the first decomposition stage was increased by 7.50℃ and 11.40℃ for the AP/Fc Br mixture and the AP/Fc Br/GFP mixture,respectively,compared to the pure AP.On the other hand,the temperature in the second decomposition stage decreased by 48.30℃ and 81.70℃ for AP/Fc Br and AP/Fc Br/GFP mixtures,respectively.It was also found that Fc Br might generate ammonia to cover the AP surface.In this case,a reaction between the methyl in Fc Br and perchloric acid caused more ammonia to appear at the AP surface,resulting in the suppression of ammonia desorption.In addition,the coarse AP particles on the quenched surface were of a concave shape relative to the binder matrix under low and high pressures when the catalysts were added.In the process,the decline at the AP/HTPB interface was only exhibited in the propellant with the addition of Ce-Fc-MOF.The ratio of the gas-phase temperature gradient of the propellants containing catalysts was reduced significantly below and above the characteristic pressure,rather than 3.6 times of the difference in the blank propellant.Overall,the obtained results demonstrated that the pressure exponent could be effectively regulated and controlled by adjusting the propellant local heat and mass transfer under high and low pressures.

Parental Educational Expectations,Academic Pressure,and Adolescent Mental Health:An Empirical Study Based on CEPS Survey Data

Background:This study aimed to investigate the relationship between parental educational expectations and adolescent mental health problems,with academic pressure as a moderating variable.Methods:This study was based on the baseline data of the China Education Panel Survey,which was collected within one school year during 2013–2014.It included 19,958 samples from seventh and ninth graders,who ranged from 11 to 18 years old.After removing missing values and conducting relevant data processing,the effective sample size for analysis was 16344.The OLS(Ordinary Least Squares)multiple linear regression analysis was used to examine the relationship between parental educational expectations,academic pressure,and adolescents’mental health problems.In addition,we established an interaction term between parents’educational expectations and academic pressure to investigate the moderating effect of academic stress.Results:The study found that adolescents whose parents had high educational expectations reported less mental health problems.(β=−0.195;p<0.001).Additionally,adolescents who had high academic pressure reported more mental health problems.(β=0.649;p<0.001).Furthermore,the study found that academic pressure had a significant moderating effect on the relationship between parental educational expectations and adolescents’mental health problems(β=0.082;p<0.001).Conclusion:Parental educational expectations had a close relationship with adolescents’mental health problems,and academic pressure moderated this relationship.For those adolescents with high levels of academic pressure,the association between high parental educational expectations and mental health problems became stronger.On the contrary,for those adolescents with low levels of academic pressure,the association between high parental educational expectations and mental health problems became weaker.These findings shed new light on how parental educational expectations affected adolescent mental health problems and had significant implications for their healthy development.

Lateral earth pressure of granular backfills on retaining walls with expanded polystyrene geofoam inclusions under limited surcharge loading

Existing studies have focused on the behavior of the retaining wall equipped with expanded polystyrene(EPS)geofoam inclusions under semi-infinite surcharge loading rather than limited surcharge loading.In this paper,the failure mode and the earth pressure acting on the rigid retaining wall with EPS geofoam inclusions and granular backfills(henceforth referred to as EPS-wall),under limited surcharge loading are investigated through two-and three-dimensional model tests.The testing results show that different from the sliding of almost all the backfill in the EPS-wall under semi-infinite surcharge loading,only an approximately triangular backfill slides in the wall under limited surcharge loading.The distribution of the lateral earth pressure on the EPS-wall under limited surcharge loading is non-linear,and the distribution changes from the increase of the wall depth to the decrease with the increase of the limited surcharge loading.An approach based on the force equilibrium of a differential element is developed to predict the lateral earth pressure behind the EPS-wall subjected to limited surcharge loading,and its performance was fully validated by the three-dimensional model tests.

At-rest lateral earth pressure of compacted expansive soils:Experimental investigations and prediction approach

This paper presents experimental studies on a compacted expansive soil,from Nanyang,China for investigating the at-rest lateral earth pressureσL of expansive soils.The key studies include(i)relationships between theσL and the vertical stressσV during soaking and consolidation,(ii)the influences of initial dry densityρd0 and moisture content w 0 on the vertical and lateral swelling pressures at no swelling strain(i.e.σV0 andσL0),and(iii)evolution of theσL during five long-term wetting-drying cycles.Experimental results demonstrated that the post-soakingσL-σV relationships are piecewise linear and their slopes in the passive state(σL>σV)and active state(σL<σV)are similar to that of the consolidationσL-σV relationships in the normal-and over-consolidated states,respectively.The soakingσL-σV relationships converge to the consolidationσL-σV relationships at a thresholdσV where the interparticle swelling is restrained.TheσL0 andσV0 increase monotonically withρd0;however,they show increasing-then-decreasing trends with the w 0.The extent of compaction-induced swelling anisotropy,which is evaluated byσL0/σV0,reduces with an increase in the compaction energy and molding water content.TheσL reduces over moisture cycles and the stress relaxation in theσL during soaking is observed.An approach was developed to predict the at-rest soakingσL-σV relationships,which requires conventional consolidation and shear strength properties and one measurement of theσL-σV relationships during soaking.The proposed approach was validated using the results of three different expansive soils available in the literature.

The effectiveness of physical activity interventions on blood pressure in children and adolescents:A systematic review and network meta-analysis

Background:High blood pressure(BP)is a major contributor to mortality and cardiovascular diseases.Despite the known benefits of exercise for reducing BP,it is crucial to identify the most effective physical activity(PA)intervention.This systematic review and network meta-analysis(NMA)aimed to evaluate the available evidence on the effectiveness of various PA interventions for reducing BP and to determine their hierarchy based on their impact on BP.Methods:A search of PubMed,SPORTDiscus,PsycINFO,Web of Science,CINAHL,Cochrane,and Eric databases was conducted up to December 2022 for this systematic review and NMA.Randomized controlled trials and quasi-experimental studies targeting healthy children and adolescents aged 6-12 years old were included in this study.Only studies that compared controlled and intervention groups using PA or exercise as the major influence were included.We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses(PRISMA)guidelines.Three independent investigators performed the literature screening,data extraction,and risk of bias assessment.We used Bayesian arm-based NMA to synthesize the data.The primary outcomes were systolic BP and diastolic BP.We calculated the mean differences(MDs)in systolic BP and diastolic BP before and after treatment.Mean treatment differences were estimated using NMA and random-effect models.Results:We synthesized 27 studies involving 15,220 children and adolescents.PA combined with nutrition and behavior change was the most effective intervention for reducing both systolic BP and diastolic BP(MD=-8.64,95%credible interval(95%CI):-11.44 to-5.84;MD=-6.75,95%CI:-10.44 to-3.11),followed by interventions with multiple components(MD=-1.39,95%CI:-1.94 to-0.84;MD=-2.54,95%CI:-4.89 to-0.29).Conclusion:Our findings suggest that PA interventions incorporating nutrition and behavior change,followed by interventions with multiple components,are most effective for reducing both systolic BP and diastolic BP in children and adolescents.

Water-induced physicochemical and pore changes in limestone for surrounding rock across pressure aquifers

Osmotic water alters the physicochemical properties and internal structures of limestone.This issue is particularly critical in tunnel construction across mountainous regions with aquifers,where pressurized groundwater can destabilize the limestone-based surrounding rock.Thus,systematic research into the physicochemical properties and pore structure changes in the limestone under pressurized water is essential.Additionally,it is essential to develop an interpretable mathematical model to accurately depict how pressurized osmotic water weakens limestone.In this research,a specialized device was designed to simulate the process of osmotic laminar flow within limestone.Then,four main tests were conducted:mass loss,acoustic emission(AE),mercury intrusion porosimetry(MIP),and fluorescence analysis.Experimental results gained from tests led to the development of a“Particle-pore throat-water film”model.Proposed model explains water-induced physicochemical and pore changes in limestone under osmotic pressure and reveals evolutionary mechanisms as pressure increases.Based on experimental results and model,we found that osmotic pressure not only alters limestone composition but also affects pore throats larger than 0.1μm.Furthermore,osmotic pressure expands pore throats,enhancing pore structure uniformity,interconnectivity,and permeability.These effects are observed at a threshold of 7.5 MPa,where cohesive forces within the mineral lattice are surpassed,leading to the breakdown of erosion-resistant layer and a significant increase in hydrochemical erosion.

Effects of confining pressure and pore pressure on multipole borehole acoustic field in fluid-saturated porous media

In-situ stress is a common stress in the exploration and development of oil reservoirs. Therefore, it is of great significance to study the propagation characteristics of borehole acoustic waves in fluid-saturated porous media under stress.Based on the acoustoelastic theory of fluid-saturated porous media, the field equation of fluid-saturated porous media under the conditions of confining pressure and pore pressure and the acoustic field formula of multipole source excitation in open hole are given. The influences of pore pressure and confining pressure on guided waves of multipole borehole acoustic field in fluid-saturated porous media are investigated. The numerical results show that the phase velocity and excitation intensity of guided wave increase significantly under the confining pressure. For a given confining pressure, the phase velocity of the guided wave decreases with pore pressure increasing. The excitation intensity of guided wave increases at low frequency and then decreases at high frequency with pore pressure increasing, except for that of Stoneley wave which decreases in the whole frequency range. These results will help us get an insight into the influences of confining pressure and pore pressure on the acoustic field of multipole source in borehole around fluid-saturated porous media.

Pressure generation under deformation in a large-volume press

Deformation can change the transition pathway of materials under high pressure,thus significantly affects physical and chemical properties of matters.However,accurate pressure calibration under deformation is challenging and thereby causes relatively large pressure uncertainties in deformation experiments,resulting in the synthesis of complex multiphase materials.Here,pressure generations of three types of deformation assemblies were well calibrated in a Walker-type largevolume press(LVP)by electrical resistance measurements combined with finite element simulations(FESs).Hard Al_(2)O_(3) or diamond pistons in shear and uniaxial deformation assemblies significantly increase the efficiency of pressure generation compared with the conventional quasi-hydrostatic assembly.The uniaxial deformation assembly using flat diamond pistons possesses the highest efficiency in these deformation assemblies.This finding is further confirmed by stress distribution analysis based on FESs.With this deformation assembly,we found shear can effectively promote the transformation of C60 into diamond under high pressure and realized the synthesis of phase-pure diamond at relatively moderate pressure and temperature conditions.The present developed techniques will help improve pressure efficiencies in LVP and explore the new physical and chemical properties of materials under deformation in both science and technology.