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.

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.

Do changes in intracoronary pressure aid coronary spasm diagnosis using the spasm provocation test?

BACKGROUND Although the spasm provocation test(SPT)can diagnose coronary spasms,it would be helpful if it could also predict their occurrence.AIM To investigate whether coronary spasms can be predicted using changes in intracoronary artery pressure measured using a pressure wire during the SPT.METHODS Seventy patients underwent SPTs with pressure-wire measurement of intracoronary artery pressure.During each SPT,the pressure wire was advanced into the distal portion of the right coronary artery(RCA)and left anterior descending coronary artery,and the ratio of intracoronary pressure to aortic pressure(Pd/Pa)was monitored.Coronary spasm was defined as an arterial narrowing of>90%in response to the administration of acetylcholine(ACh),with chest symptoms and/or ischemic electrocardiographic changes.ACh was administered to the RCA at low,moderate,or high doses of 20,50,or 80μg,respectively,and to the left coronary artery(LCA)at low,moderate,or high doses of 50,100,or 200μg,respectively.Coronary arteries with coronary spasms at low doses of ACh were defined as group L,and those with coronary spasms at moderate or high doses were defined as group MH.Those who did not occur coronary spasms at any ACh dose were designated as group N.RESULTS Among the 132 coronary arteries assessed using a pressure wire,there were 49 in group N,25 in group L,and 58 in group MH.Baseline Pd/Pa was the lowest in group L(P=0.001).The decrease in the Pd/Pa between baseline to low doses of ACh was lower in group MH than in group N(P<0.001).A receiver-operating characteristics analysis showed that the cutoff baseline Pd/Pa value for predicting group L was 0.95,with a sensitivity of 0.600(15/25)and a specificity of 0.713(76/107)and that the cutoff value of Pd/Pa from baseline to low doses of ACh for predicting group MH was−0.04,with a sensitivity of 0.741(43/58)and a specificity of 0.694(34/49).CONCLUSION These findings suggest that indices of intracoronary pressure during SPT may be useful means for predicting the occurrence of coronary spasms.

Pressure-induced magnetic phase and structural transition in SmSb_(2)

Motivated by the recent discovery of unconventional superconductivity around a magnetic quantum critical point in pressurized CeSb_(2),here we present a high-pressure study of an isostructural antiferromagnetic(AFM) SmSb_(2) through electrical transport and synchrotron x-ray diffraction measurements.At P_C~2.5 GPa,we found a pressure-induced magnetic phase transition accompanied by a Cmca→P4/nmm structural phase transition.In the pristine AFM phase below P_C,the AFM transition temperature of SmSb_(2) is insensitive to pressure;in the emergent magnetic phase above P_C,however,the magnetic critical temperature increases rapidly with increasing pressure.In addition,at ambient pressure,the magnetoresistivity(MR) of SmSb_(2) increases suddenly upon cooling below the AFM transition temperature and presents linear nonsaturating behavior under high field at 2 K.With increasing pressure above P_C,the MR behavior remains similar to that observed at ambient pressure,both in terms of temperature-and field-dependent MR.This leads us to argue an AFM-like state for SmSb_(2) above P_C.Within the investigated pressure of up to 45.3 GPa and the temperature of down to 1.8 K,we found no signature of superconductivity in SmSb_(2).

Screening, Treatment and Control of High Blood Pressure on Five Sites in Mali

Introduction: High blood pressure is defined as blood pressure greater than or equal to 140 mm Hg for systolic and or 90 mm Hg for diastolic. It constitutes a major public health problem, the leading chronic disease in the world. The objective was to determine the prevalence, treatment rate and control of hypertension. Methods: This was a cross-sectional and descriptive study which took place over a period of 6 months in a hospital environment and in the general population. Results: Of the 1000 participants, 637 had hypertension, giving a prevalence of 63.70% with a female predominance. Thirty-three percent (33%) were unaware of their high blood pressure. The age group 60 and more was the most represented (44%). A proportion of 33 and 23.20 were overweight and obese participants, respectively. Male subjects were more overweight than female, unlike obesity which was more common among female subjects. Sixty-two percent (62%) of hypertensives were treated, of whom 44% were non-compliant. The excessively high cost and consumption of medications as needed were the main factors in therapeutic non-compliance. Twenty-two percent (22%) of all hypertensive patients and 35% of treated hypertensive patients were controlled. Women were more treated but less observant and less controlled than men. Therapeutic coverage and combination therapy rates were lower in rural areas. Hypertensives who had a high level of education were better treated and controlled than those who had no level. Conclusion: High blood pressure remains a real public health problem in Mali. It is more common in people aged 60 and over and in females. One in three hypertensives were unaware of their hypertension. The majority received antihypertensive treatments, but only a minority of them had their hypertension controlled.

Economic Stress, Precariousness and Risk of High Blood Pressure: A Descriptive Survey of Life Models within Households of the Central Region of Cameroon

Context/Objective: High blood pressure (HBP) currently represents the most widespread chronic non-communicable disease in Cameroon. The increase in its prevalence in the country is the result of multiple factors including economic stress imposed by precariousness, poor living conditions, sources of anxiety, anguish, depression and other behavioral disorders. Economic stress is a globalizing concept that integrates into a purely hermeneutic approach, a particular functioning of the nervous system of an individual who faces employment problems and precarious remuneration conditions. The non-satisfaction by an individual of his basic needs due to insufficient financial means can cause him to become irritable, aggressive, and socially and symbolically isolated, thereby increasing the desire to resort to morbid life models such as excessive consumption of narcotics and other psychoactive substances often associated with high blood pressure. The fight against the emergence of BPH is a complex, multifaceted and multifactorial reality that requires taking into account economic stress. The main objective of this survey is to describe the situation of economic stress within the Cameroonian population, which imposes precariousness and life models at risk of high blood pressure. Specifically, we determined the level of household income and the sources of income. Methods: A cross-sectional survey with a descriptive aim among five hundred households in the Central Region of Cameroon was conducted. A probabilistic technique called simple randomness was used. The number of households to be surveyed was determined indirectly using the Cochrane formula. Data collection in face-to-face mode using a physical questionnaire took place from July 1 to August 31, 2023, after obtaining ethical clearance from the Regional Health Research Ethics Committee, Human from the Center and an administrative authorization for data collection. Regarding their processing, the data was grouped during processing in Excel sheets. Normality and reliability tests of the collected data were carried out. For this, the Chi-square test was used for data with a qualitative value and that of Kolmogorov-Sminorf for data with a quantitative value. Descriptive analysis was possible using R software version 3.2, SPSS version 25.0, XLSTAT 2016, PAST and EXCEL programs from Microsoft Office 2013. Results: The main results highlight economic stress, with 45.60% of households surveyed earning less than US$154 per month;55% of household heads were women in single-parent families;14% of household heads were unemployed, 22% worked in the private sector and 19% were self-employed. This general economic situation leads to precarious living conditions, thereby increasing the risk of high blood pressure among the Cameroonian population.

Blood Pressure Estimation with Phonocardiogram on CNN-Based Approach

Monitoring blood pressure is a critical aspect of safeguarding an individual’s health,as early detection of abnormal blood pressure levels facilitates timely medical intervention,ultimately leading to a reduction in mortality rates associated with cardiovascular diseases.Consequently,the development of a robust and continuous blood pressure monitoring system holds paramount significance.In the context of this research paper,we introduce an innovative deep learning regression model that harnesses phonocardiogram(PCG)data to achieve precise blood pressure estimation.Our novel approach incorporates a convolutional neural network(CNN)-based regression model,which not only enhances its adaptability to spatial variations but also empowers it to capture intricate patterns within the PCG signals.These advancements contribute significantly to the overall accuracy of blood pressure estimation.To substantiate the effectiveness of our proposed method,we meticulously gathered PCG signal data from 78 volunteers,adhering to the ethical guidelines of Suranaree University of Technology(Human Research Ethics number EC-65-78).Subsequently,we rigorously preprocessed the dataset to ensure its integrity.We further employed a K-fold cross-validation procedure for data division and alignment,combining the resulting datasets with a CNNfor blood pressure estimation.The experimental results are highly promising,yielding aMeanAbsolute Error(MAE)and standard deviation(STD)of approximately 10.69±7.23 mmHg for systolic pressure and 6.89±5.22 mmHg for diastolic pressure.Our study underscores the potential for precise blood pressure estimation,particularly using PCG signals,paving the way for a practical,non-invasive method with broad applicability in the healthcare domain.Early detection of abnormal blood pressure levels can facilitate timely medical interventions,ultimately reducing cardiovascular disease-related mortality rates.

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.

Buckling Properties of Water-Drop-Shaped Pressure Hulls with Various Shape Indices Under Hydrostatic External Pressure

The water-drop-shaped pressure hull has a good streamline,which has good application prospect in the underwater observatory.Therefore,this study conducted analytical,experimental and numerical investigation of the buckling properties of water-drop-shaped pressure hulls under hydrostatic pressure.A water-drop experiment was conducted to design water-drop-shaped pressure hulls with various shape indices.The critical loads for the water-drop-shaped pressure hulls were resolved by using Mushtari’s formula.Several numerical simulations including linear buckling analysis and nonlinear buckling analysis including eigenmode imperfections were performed.The results indicated that the critical loads resolved by Mushtari's formula were in good agreement with the linear buckling loads from the numerical simulations.This formula can be extended to estimate the buckling capacity of water-drop-shaped pressure hulls.In addition,three groups of pressure hulls were fabricated by using stereolithography,a rapid prototyping technique.Subsequently,three groups of the pressure hulls were subjected to ultrasonic measurements,optical scanning,hydrostatic testing and numerical analysis.The experimental results were consistent with the numerical results.The results indicate that the sharp end of the water-drop-shaped pressure hulls exhibited instability compared with the blunt end.This paper provides a new solution to the limitations of experimental studies on the water-drop-shaped pressure hulls as well as a new configuration and evaluation method for underwater observatories.

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.

Stability and melting behavior of boron phosphide under high pressure

Boron phosphide(BP)has gained significant research attention due to its unique photoelectric and mechanical properties.In this work,we investigated the stability of BP under high pressure using x-ray diffraction and scanning electron microscope.The phase diagram of BP was explored in both B-rich and P-rich environments,revealing crucial insight into its behavior at 5.0 GPa.Additionally,we measured the melting curve of BP from 8.0 GPa to 15.0 GPa.Our findings indicate that the stability of BP under high pressure is improved within B-rich and P-rich environments.Furthermore,we report a remarkable observation of melting curve frustration at 10.0 GPa.This study will enhance our understanding of stability of BP under high pressure,shedding light on its potential application in semiconductor,thermal,and light-transmitting devices.

High-pressure study on calcium azide(Ca(N_(3))_(2)):Bending of azide ions stabilizes the structure

The high-pressure structure and elastic properties of calcium azide(Ca(N_(3))_(2))were investigated using in-situ highpressure x-ray diffraction and Raman scattering up to 54 GPa and 19 GPa,respectively.The compressibility of Ca(N_(3))_(2)changed as the pressure increased,and no phase transition occurred within the pressure from ambient pressure up to 54 GPa.The measured zero-pressure bulk modulus of Ca(N_(3))_(2)is higher than that of other alkali metal azides,due to differences in the ionic character of their metal-azide bonds.Using CASTEP,all vibration modes of Ca(N_(3))_(2)were accurately identified in the vibrational spectrum at ambient pressure.In the high-pressure vibration study,several external modes(ext.)and internal bending modes(ν_(2))of azide anions(N_(3)^(-))softened up to~7 GPa and then hardened beyond that pressure.This evidence is consistent with the variation observed in the F_(E)–f_(E)data analyzed from the XRD result,where the slope of the curve changes at 7.1 GPa.The main behaviors under pressure are the alternating compression,rotation,and bending of N_(3)^(-)ions.The bending behavior makes the structure of Ca(N_(3))_(2)more stable under pressure.

A Study to Observe Pulse Pressure Variation after Induction with Propofol for General Anesthesia

Background and Aims: Pulse pressure variation (PPV) is a reliable and predictive dynamic parameter presently being utilized for fluid responsiveness. In the operating room, fluid administration based on PPV monitoring helps the physician in deciding whether to volume resuscitate or use interventions in patients undergoing surgery. Propofol is an intravenous induction agent which lowers blood pressure. There are multiple causes such as depression in cardiac output, and peripheral vasodilatation for hypotension. We undertook this study to observe the utility of PPV as a guide to fluid therapy after propofol induction. Primary outcome of our study was to monitor PPV as a marker of fluid responsiveness for the hypotension caused by propofol induction. Secondary outcome included the correlation of PPV with other hemodynamic parameters like heart rate (HR), systolic blood pressure (SBP), and diastolic blood pressure (DBP);after induction with propofol at regular interval of time. Methods: A total number of 90 patients were recruited. Either of the radial artery was then cannulated under local anaesthesia with 20G VygonLeadercath arterial cannula and invasive monitoring transduced. A baseline recording of heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP) and PPV was then recorded. Patients were then induced with predetermined doses of propofol (2 mg/kg) and recordings of HR, SBP, DBP, and PPV were taken at 5, 10 and 15 minutes. Results: Intraoperatively, PPV was significantly higher at 5 minutes and significantly lower at 15 minutes after induction. It was observed that there were no statistically significant correlations between PPV and SBP or DBP. PPV was strongly and directly associated with HR. Conclusion: We were able to establish that PPV predicts fluid responsiveness in hypotension caused by propofol induction;and can be used to administer fluid therapy in managing such hypotension. However, PPV was not directly correlated with hypotension subsequent to propofol administration.

Ultrafast dynamics in photo-excited Mott insulator Sr_(3)Ir_(2)O_7 at high pressure

High-pressure ultrafast dynamics,as a new crossed research direction,are sensitive to subtle non-equilibrium state changes that might be unresolved by equilibrium states measurements,providing crucial information for studying delicate phase transitions caused by complex interactions in Mott insulators.With time-resolved transient reflectivity measurements,we identified the new phases in the spin–orbit Mott insulator Sr_(3)Ir_(2)O_7 at 300 K that was previously unidentified using conventional approaches such as x-ray diffraction.Significant pressure-dependent variation of the amplitude and lifetime obtained by fitting the reflectivity?R/R reveal the changes of electronic structure caused by lattice distortions,and reflect the critical phenomena of phase transitions.Our findings demonstrate the importance of ultrafast nonequilibrium dynamics under extreme conditions for understanding the phase transition of Mott insulators.

Electric-controlled pressure relief valve for enhanced safety in liquid-cooled lithium-ion battery packs

The liquid-cooled battery energy sto rage system(LCBESS) has gained significant attention due to its superior thermal management capacity.However,liquid-cooled battery pack(LCBP) usually has a high sealing level above IP65,which can trap flammable and explosive gases from battery thermal runaway and cause explosions.This poses serious safety risks and challenges for LCBESS.In this study,we tested overcharged battery inside a commercial LCBP and found that the conventionally mechanical pressure relief valve(PRV) on the LCBP had a delayed response and low-pressure relief efficiency.A realistic 20-foot model of an energy storage cabin was constructed using the Flacs finite element simulation software.Comparative studies were conducted to evaluate the pressure relief efficiency and the influence on neighboring battery packs in case of internal explosions,considering different sizes and installation positions of the PRV.Here,a newly developed electric-controlled PRV integrated with battery fault detection is introduced,capable of starting within 50 ms of the battery safety valve opening.Furthermore,the PRV was integrated with the battery management system and changed the battery charging and discharging strategy after the PRV was opened.Experimental tests confirmed the efficacy of this method in preventing explosions.This paper addresses the safety concerns associated with LCBPs and proposes an effective solution for explosion relief.

Blood Pressure Profile and Glycemic Control of Type 2 Diabetics and Hypertensives at the Yalgado Ouedraogo University Hospital: A Review of 116 Cases

Objective: The association hypertension and diabetes is important. The two pathologies may influence each other. The aim was to study the correlation between glycemic control and blood pressure control and to determine the factors associated with blood pressure control. Methodology: This was a descriptive cross-sectional study with an analytical focus over 7 months. Patients were recruited as outpatients and all underwent ambulatory blood pressure measure, glycated hemoglobin and creatinine measurements, and assessment of compliance with treatment. Results: During this period 116 patients were collected. The predominance was female 69%. The mean age of the patients was 62 ± 7 years with a peak between 60 and 70 years. The average age of hypertension was 12 years and that of diabetes 6 1/2 years. The most frequently associated cardiovascular risk factor was a sedentary lifestyle (71.5%) after age. 57.8% of patients were not controlled at the office, with a predominance of systolic hypertension (58.2%). 61.6% of patients were controlled by ambulatory blood pressure measure, a rate of 47.8% of white coat hypertension. Glycemic control was observed in 42.2% of cases and 87% of patients had good renal function (glomerular filter rate ≥ 60 ml/mn). Therapeutic compliance was good in 53.4% of cases and dual therapy was the most used therapeutic modality 44.8% (52 patients) followed by triple therapy. The factors associated with poor blood pressure control were glycemic imbalance, non-compliance and monotherapy. Dual therapy had a protective effect. Conclusion: The association of hypertension and type 2 diabetes is frequent. The risk of occurrence increases with age. Ambulatory blood pressure measure is the best method to assess blood pressure control. Optimization of blood pressure control should also include optimization of glycemic control.

Background diseases and the number of previous intravitreal aflibercept injections on immediate intraocular pressure increase and vitreous reflux rate in phakic eyes

●AIM:To evaluate the effect of background diseases and number of previous intravitreal aflibercept injections(IVAIs)on immediate intraocular pressure(IOP)increase and vitreous reflux(VR)rate and to evaluate the correlation of both age and axial length with immediate IOP increase and VR rate.●METHODS:This study included 105 patients with cystoid macular edema secondary to retinal vein occlusion,35 patients with diabetic macular edema,69 patients with neovascular age-related macular degeneration(nAMD),and 12 patients with myopic choroidal neovascularization,which underwent first-time IVAI.The correlation of immediate IOP increase and VR rates with the four background diseases was investigated.Moreover,the correlation of age with immediate IOP increase and VR rate as well as correlation of axial length with immediate IOP increase and VR rate were evaluated.Further,54 patients with nAMD were treated with IVAI>10 times(multiple IVAIs).Moreover,the correlation of immediate IOP increase and VR rates with first-time and multiple IVAIs in nAMD was determined.●RESULTS:The immediate IOP increase(P=0.16)and VR rates(P=0.50)were almost similar among the four background diseases.The immediate postinjection IOP and age,VR rate and age,immediate postinjection IOP and axial length,or VR rate and axial length were not correlated in the four background diseases.The immediate IOP increase(P=0.66)and VR rates(P=0.28)did not significantly differ between first-time and multiple IVAIs in nAMD.●CONCLUSION:Background diseases and number of previous IVAIs have no effect on immediate IOP increase and VR rate.Further,age and axial length have no correlation on immediate IOP increase and VR rate.

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.

Data-driven modeling on anisotropic mechanical behavior of brain tissue with internal pressure

Brain tissue is one of the softest parts of the human body,composed of white matter and grey matter.The mechanical behavior of the brain tissue plays an essential role in regulating brain morphology and brain function.Besides,traumatic brain injury(TBI)and various brain diseases are also greatly influenced by the brain's mechanical properties.Whether white matter or grey matter,brain tissue contains multiscale structures composed of neurons,glial cells,fibers,blood vessels,etc.,each with different mechanical properties.As such,brain tissue exhibits complex mechanical behavior,usually with strong nonlinearity,heterogeneity,and directional dependence.Building a constitutive law for multiscale brain tissue using traditional function-based approaches can be very challenging.Instead,this paper proposes a data-driven approach to establish the desired mechanical model of brain tissue.We focus on blood vessels with internal pressure embedded in a white or grey matter matrix material to demonstrate our approach.The matrix is described by an isotropic or anisotropic nonlinear elastic model.A representative unit cell(RUC)with blood vessels is built,which is used to generate the stress-strain data under different internal blood pressure and various proportional displacement loading paths.The generated stress-strain data is then used to train a mechanical law using artificial neural networks to predict the macroscopic mechanical response of brain tissue under different internal pressures.Finally,the trained material model is implemented into finite element software to predict the mechanical behavior of a whole brain under intracranial pressure and distributed body forces.Compared with a direct numerical simulation that employs a reference material model,our proposed approach greatly reduces the computational cost and improves modeling efficiency.The predictions made by our trained model demonstrate sufficient accuracy.Specifically,we find that the level of internal blood pressure can greatly influence stress distribution and determine the possible related damage behaviors.