Prediction of Hypotension During Neuraxial Anesthesia in Patients with Pregnancy-Induced Hypertension Through Subclavian Vein Collapsibility Index

Objective:To explore and evaluate the predictive value of subclavian vein collapsibility index(SCV-CI)on hypotension during neuraxial anesthesia in patients with pregnancy-induced hypertension(PIH).Methods:Pregnant women with PIH who underwent elective cesarean section in our hospital from January to July 2021 were selected as the research subjects.Patients who experienced hypotension during anesthesia were included into the hypotension group,whereas patients who had a normal blood pressure during anesthesia were included in the normotensive group.The SCV-CI was then calculated for three respiratory cycles,the average value was taken as the base value,and the patient was monitored for another 20 minutes.The blood pressure,heart rate,blood oxygen saturation,and SCV-CI of the patients were measured,and the incidence of maternal nausea and vomiting and cord blood gas were recorded.Then,a correlation analysis was conducted on the relationship between subclavian vein collapsibility index and hypotension.A receiver operating characteristic curve was drawn to seek the threshold value of subclavian vein collapsibility index for post-anesthesia hypotension.Results:There was no significant difference in systolic blood pressure(SBP),diastolic blood pressure(DBP),and heart rate(HR)between the two groups before anesthesia(P>0.05).After anesthesia,the above indexes(SBP,103.25±12.48 mmHg;DBP,58.94±7.46 mmHg;and HR,52.96±6.48 beats/min)were significantly lower than those of the normal blood pressure group,and the difference was statistically significant(P<0.05).In comparison,the SCV-CI in the hypotension group was 35.82±4.93%greater than that in the normal blood pressure group(23.85±5.27%),and the incidence of nausea and vomiting in the hypotension group(40.0%)was significantly higher than that in the normotensive group(10.53%),and the difference was statistically significant(P<0.05).The area under the curve of SCV-CI prediction against hypotension in patients with PIH under neuraxial anesthesia was 0.825(95%CI:0.762-0.893,P<0.001),the cut-off value was 25.68%,the predictive sensitivity was 92.68%,and the specificity was 81.24%.Conclusion:SCV-CI has a good predictive value for the occurrence of hypotension in patients with PIH during neuraxial anesthesia.

Improvement in collapsibility of ZrO2 ceramic mould for investment casting of TiAl alloys

Investment casting has been widely recognized as the best option in producing TiAl components with key benefits of accuracy,versatility and integrity.The collapsibility of ceramic moulds for investment casting is critical in the manufacturing process of TiAl components due to TiAl's intrinsic brittleness at room temperature.The aim of the present research is to provide a method for production of TiAl components by investment casting in ZrO2 ceramic moulds with improved collapsibility.Slurries prepared with high polymer additions were utilized during the preparation of ceramic moulds.The stress/strain curves obtained from green and baked ceramic moulds demonstrate that the green strength was increased with the application of high polymer,while baked strength decreased,thus the collapsibility of ceramic moulds was improved.It is suggested that this result is related to the burn-out of high polymer which left a lot of cavities.The experimental findings were also verified by the investment casting of "I"-shaped TiAl components.

Collapsibility of odds ratios for a continuous outcome variable

The sign of an association measure between two varibles may be strongly affected and even be reversed after marginalization over a backgruoud variable, which is the well-known Yule-Simpson paradox.Odds ratios are strongly collapsible over a background variable if they remain unchanged no matter how the background variable is partially pooled.In this paper, we firstly give some definitions and notations about odds ratios between a dichotomous explanatory variable and a continuous response variable.Then, we present conditions for simple collapsibility of odds ratios.Further, necessary and sufficient conditions are given for strong collapsibility of odds ratios for continuous outcome variable.

Controlling Soil Collapsibility Due to Water Intrusion by Rigid Foundation System with Reinforced Cushion

Since collapsible soils are been mostly transported by wind and deposited in arid or semi-arid regions, they founded in a state of unsaturated condition. In addition, engineering filling when placed in a certain none want density, undesired settlement will be predictable either due to wetting or due to loading on these soil deposits. Collapsibility study is important for the foundation design and construction on these soils. The most foundation systems used on these soils are isolated and strip footing connected with concrete tie beams. Therefore studying rigid foundation system resting on partially saturated collapsible soil/deposits is very important. The present work investigated using rigid strip footing resting in collapsible soils to study the effect of stress interference due to progressive wetting depth from leakage of surface water on collapsibility settlement. The study has been investigated the influence of different behavior of strip footing and inverted T-section strip footing rigidity system resting on unsaturated soil by numerical analysis using the finite element program PLAXIS 2D. The partially saturated collapsible soil is stimulated using the Mohr-Coulomb soil model. The significance parameters are considered two types of footing systems, collapsible soil thickness, use of sand cushion with geo-grid reinforcement at the bottom third of its thickness, and different clear spacing between source of surface water and strip footings on the stress-settlement relationship. The results of this study confirmed that the most important soil parameters in this problem are the use of reinforced sand cushion, decrease applied stress as well as rigid inverted T-section strip footing are more suitable for controlling Soil collapsibility, while the settlement is found to decrease. To avoid many observation of spread footing disaster that founded and rest on collapse soil. In addition, the results can be guide for design engineers, how to choose foundation type and the effect of spacing water resource.

Microstructure evolution of loess under multiple collapsibility based on nuclear magnetic resonance and scanning electron microscopy

In recent years, the acceleration of urbanization in loess areas has prompted frequent dismantling and reconstruction of old urban areas. Demolition and reconstruction of buildings involve multiple collapses of the foundation. To study microstructure evolution of loess under multiple collapsibility, this paper selects undisturbed loess samples from Guyuan, Northwest China for multiple compression tests. Using nuclear magnetic resonance(NMR) imaging and scanning electron microscopy(SEM) as auxiliary methods, a combination of qualitative and quantitative analyses was used to study the microstructure of loess samples before and after various number of collapses under different pressures. Results show that the loess does undergo multiple collapse under 200 kPa pressure. Pore is an important reason for loess collapse. The initial collapse comes primarily from the compression of macropores and mesopores, and the second collapse comes primarily from mesopore compression. The compression process of loess can be roughly divided into two stages. First, under the action of dissolution and compression, the relative displacement of soil particles occurs. Macropores and mesopores are destroyed first, generating small pores. Second, with increasing pressure and times of collapses, pore compression gradually transforms into small pore compression. During the first collapse, particle aggregates disintegrate due to water and pressure. However, with increasing times of collapses, the contact relationship between particles gradually changes from the point contact to face contact. Loess particles tend to gradually become rounded. The study of the microstructure provides the possibility to further reveal the mechanism of multiple collapsibility of loess.

Evaluation and Analysis of the Effect of Lignin Amelioration on Loess Collapsibility

The road subgrade and road surface in collapsible loess area are prone to many engineering diseases such as uneven subgrade settlement,insufficient bearing capacity of soaked foundation,collapse and instability of sub-grade side slope due to the special properties of loess.As an environment-friendly,low-cost soil modifier with good adhesion and chelation properties,lignin has been considered to be used in highway subgrade construction.In order to explore the effect of lignin on loess,the compressive and collapsible properties of modified loess with different lignin contents were analyzed based on consolidation compression test.The improvement mechanism of lignin on loess collapsibility was studied by means of infiltration test and SEM test.The results show that lignin fibers can promote the agglomeration of loose particles and form a network structure in the soil particle pores,enhance the cementation strength between particles and soil skeleton,and reduce the permeability of loess.With the increase of lignin fiber content,the improvement degree of loess collaps ility shows a trend of first increasing and then decreasing.When the lignin fiber content is 2%,the effect is the best,and the improved loess ollapsi-bility is eliminated.

Early Devonian Post-collisional Granitic Magmatism in the North Qilian Orogenic Belt,Western China:Insights into Lithospheric Delamination and Orogenic Collapse

Post-collisional magmatism contains important clues for understanding the reworking and growth of continental crust,as well as lithospheric delamination and orogenic collapse.Early Devonian magmatism has been identified in the North Qilian Orogenic Belt(NQOB).This paper reports an integrated study of petrology,whole-rock geochemistry,Sm-Nd isotope and zircon U-Pb dating,as well as Lu-Hf isotopic data,for two Early Devonian intrusive plutons.The Yongchang and Chijin granites yield zircon U-Pb ages of 394-407 Ma and 414 Ma,respectively.Both of them are characterized by weakly peraluminous to metaluminous without typical aluminium-rich minerals,LREE-enriched patterns with negative Eu anomalies and a negative correlation between P_(2)O_(5) and SiO_(2) contents,consistent with geochemical features of I-type granitoids.Zircons from the studied granites display negative to weak positive ε_(Hf)(t)values(−5.7 to 2.1),which agree well with those of negative ε_(Nd)(t)values(−6.4 to−2.9)for the whole-rock samples,indicating that they were derived from the partial melting of Mesoproterozoic crust.Furthermore,low Sr/Y ratios(1.13-21.28)and high zircon saturation temperatures(745℃ to 839℃,with the majority being>800℃)demonstrated a relatively shallow depth level below the garnet stability field and an additional heat source.Taken together,the Early Devonian granitic magmatism could have been produced by the partial melting of ancient crustal materials heated by mantle-derived magmas at high-temperature and low-pressure conditions during postcollisional extensional collapse.The data obtained in this study,when viewed in conjunction with previous studies,provides more information about the tectonic processes that followed the closure of the North Qilian Ocean.The tectonic transition from continental collision to post-collisional delamination could be constrained to~430 Ma,which is provided by the sudden decrease of Sr/Y and La/Yb ratios and an increase in zircon ε_(Hf)(t)values for granitoids.A two-stage tectonic evolution model from continental collision to post-collisional extensional collapse for the NQOB includes(a)continental collision and crustal thickening during ca.455-430 Ma,characterized by granulite-facies metamorphism and widespread low-Mg adakitic magmatism;(b)post-collisional delamination of thickened continental crust and extensional collapse of orogen during ca.430-390 Ma,provided by coeval high-Mg adakitic magmatism,A-type granites and I-type granitoids with low Sr-Y ratios.

Airblast evolution initiated by Wangjiayan landslides in the M_(s)8.0 Wenchuan earthquake and its destructive capacity analysis

Airblasts,as one common phenomenon accompanied by rapid movements of landslides or rock/snow avalanches,commonly result in catastrophic damages and are attracting more and more scientific attention.To quantitatively analyze the intensity of airblast initiated by landslides,the Wangjiayan landslide,occurred in the Wenchuan earthquake,is selected here with the landslide propagation and airblast evolution being studied using FLUENT by introducing the Voellmy rheological law.The results reveal that:(1)For the Wangjiayan landslide,its whole travelling duration is only 12 s with its maximum velocity reaching 36 m/s at t=10 s;(2)corresponding to the landslide propagation,the maximum velocity,28 m/s,of the airblast initiated by the landslide also appears at t=10 s with its maximum pressure reaching594.8 Pa,which is equivalent to violent storm;(3)under the attack of airblast,the load suffered by buildings in the airblast zone increases to 1300 Pa at t=9.4 s and sharply decreased to-7000 Pa as the rapid decrease of the velocity of the sliding mass at t=10 s,which is seriously unfavorable for buildings and might be the key reason for the destructive collapse of buildings in the airblast zone of the Wangjiayan landslide.

Collapse Behavior of Pipe-Framed Greenhouses with and without Reinforcement under Snow Loading:A 3-D Finite Element Analysis

The present paper first investigates the collapse behavior of a conventional pipe-framed greenhouse under snow loading based on a 3-D finite element analysis,in which both geometrical and material non-linearities are considered.Three snow load distribution patterns related to the wind-driven snow particle movement are used in the analysis.It is found that snow load distribution affects the deformation and collapse behavior of the pipe-framed greenhouse significantly.The results obtained in this study are consistent with the actual damage observed.Next,discussion is made of the effects of reinforcements by adding members to the basic frame on the strength of the whole structure,in which seven kinds of reinforcement methods are examined.A buckling analysis is also carried out.The results indicate that the most effective reinforcement method depends on the snow load distribution pattern.

Progressive Collapse Resistance of a New Staggered Story Isolated System

A new staggered isolated system developed from the mid-story isolated system is the new staggered story isolated system. There are not many studies on this structure currently. In this study, an 18-story new staggered story isolated system model is established using SAP2000. The dynamic nonlinear dynamic alternate method is used to analyze the structure against progressive collapse. Results show that the structure has good resistance to progressive collapse, and there is no progressive collapse under each working condition. The progressive collapse does not occur for the case of removing only one vertical structural member of the new staggered of isolated system. The side column has big influence on this isolated structures’ progressive collapse;the removal of vertical structural member of the isolation layer has less impact on the structure than the removal of the bottom vertical structural member. After the removing of the member, the internal force of the structure will be redistributed, and the axial force of the adjacent columns will change obviously, showing a trend of “near large and far small”.

A new method of studying collapsibility of loess

A new triaxial testing system that could control suction in wetting-induced collapsible tests was success-fully developed to study the suction effects on wetting-induced collapsible deformation.The pedestal of the triaxial cell was made up of two parts,and the equipment not only could control suction but also could make water accessible to soil.A pressure/volume-controlled equip-ment was combined with the triaxial system to measure the water volume absorbed by samples accurately and to add pressure on water to filtrate into the sample.The apparatus could measure volume change precisely and keep the deviator stress unvaried,as well as measure the volume of water filtrating into the samples exactly.A triaxial collapsible testing procedure was described using the new apparatus for undisturbed collapsible loess with controlled suction.Furthermore,a series of double triaxial collapsible tests were conducted under different suctions and the same net cell pressure,and tests under different net cell pressures and the same suction were also done.It was indicated that the collapsible deformation increased with the increasing suction,and the effect of the net cell pressure on collapsible deformation was remarkable.The new triaxial apparatus was a useful facility to study the collapsible behavior of loess.

Rapid report of seismic damage to buildings in the 2022 M 6.8 Luding earthquake,China

The report summarizes the observed damage to a variety of buildings near the epicenter of the M6.8 Luding earthquake in Sichuan Province,China.They include base-isolated buildings,multi-story reinforced concrete(RC)frame buildings,and masonry buildings.The near-field region is known to be tectonically highly active,and the local intensity level is the highest,that is,0.4g peak ground acceleration(PGA)for the design basis earthquake,in the Chinese zonation of seismic ground motion parameters.The extent of damage ranged from the weak-story collapse that claimed lives to the extensive nonstructural damage that suspended occupancy.The report highlights the first observation of the destruction of rubber bearings and viscous dampers in the isolation layer of Chinese seismically isolated buildings.It also features the rare observation of the brittle shear failure of RC columns in moment-resisting frames in a region of such a high seismic design requirement.Possible reasons that may have attributed to the reported damage are suggested by providing facts observed in the field.However,careful forensic analyses are needed before any conclusive judgment can be made.

Observation of the poloidally asymmetrical density perturbation of sawtooth collapse on J-TEXT

The detailed density perturbations provided by the advanced polarimeter-interferometer system(Polaris) during sawtooth collapse on the Joint Texas Experimental Tokamak(J-TEXT) are reported in this article.During a sawtooth collapse and the crash of plasma pressure at the center,it is found that the increase in density in the region between the inversion radius and mixing radius is poloidally asymmetrical,while the increase in temperature is poloidally symmetrical.The poloidal location where the density increases is dependent on the phase of the precursory m/n=1/1 kink mode.It is always out of phase with the hot core of the m/n=1/1 mode.The behaviors of density perturbations during sawtooth collapse observed in J-TEXT are beyond the expectations of the standard model,and this can shed new light on the understanding of sawtooth collapse.

Numerical Study on the Pulsation Characteristics of An Attached Air Bubble Under A Nearby Oscillating Bubble

Numerical simulations of the non-spherical evolution of a pulsating bubble interacting with a stationary air bubble attached to a fixed structure were performed using a three-dimensional boundary integral method by implementing the mirror image method to simplify the processing of the numerical model. Code validation was accomplished by comparing the numerical results with the laboratory experimental data obtained in our previous study. Complex phenomena were observed, including three types of bubble jet forms, which depended strongly on the distance parameter with respect to the initial location of the bubble from the plate, the bubble strength parameter and the initial air bubble radius parameters. The results of the simulations provide detail insight into interesting bubble jetting phenomena,such as bubble splitting, jets moving away from the plate, and bubble shedding. The dimensionless distance parameter and the initial air bubble radius parameter play a major role in determining the shapes of two bubbles and the jetting direction. The air bubble strength parameter did not change the bubble jet direction but influenced the bubble shape.The detachment of the attached air bubble under oscillating bubble suction was easily observed for a small initial air bubble. These results showed that bubble jetting toward the plate was manipulated through the effect of attached air bubble, and that cavitation-based applications and underwater explosion bubble may benefit from this erosion mitigation approach.

Relationship between gravitational flap structures in the backlimb of anticlinal breakthrough Fault-Propagation Folds:case study of the Southern-Central Tunisian Atlas

The development of orogenic belts structures in the Southern-Central Tunisian Atlas is influenced by the evolution of tectonic activities during different phases,which are also closely linked to the formation of gravitational collapse structure.The typical example is that of the northern flank of the Jebel Orbata particularly the Ben Zannouch fold.It is an asymmetrical anticline interpreted by the model of“Fault Propagation Folds”.The development of the Ben Zannouch structures is resulted from landslides,scree falls and inverted layers plunging to the south.The direction of resulted gravitational structure is parallel to the main thrust direction of the Bou Omrane anticline.The thrust activity of Bou Omrane fault is associated to the important paleo-slope facing south and plastic lithology(incompetent marl layers)of outcropped series,facilitates the development of the Ben Zannouch Flap structure.The definition of gravitational collapse structures for the first time in Tunisia particularly in the northern flank of the Jebel Orbata is controlled by many principal structural conditions:fragmentation of the landslide surfaces,rheology and topography.Other regional factors can be distinguished in the Southern-Central Tunisian Atlas as the seismic activity of the pre-existing Gafsa fault reactivated during compressive phases and the weather conditions during the postglacial period.

Preliminary investigation of building damage in Hatay under February 6,2023 Turkey earthquakes

On February 6,2023,an M_(w)7.8 earthquake hit the south of Kahramanmaras prefecture,Turkey,followed by another M_(w)7.5 earthquake after nine hours in the middle region of the Kahramanmaras prefecture.More than 84,000 buildings collapsed or were severely damaged,and more than 50,000 lives were lost in Turkey and Syria.Some of the authors,as members of Chinese rescue team,entered Antakya,Hatay prefecture,and investigated the damaged buildings.This paper first summarizes the damage patterns of buildings and provides three reasons for the massive number of collapsed buildings;i.e.,the lack of seismic measures for better ductility,site effects such as liquefaction and surface rupture,and pronounced low-frequency components of the ground motions.Next,the seismic responses of two typical buildings are calculated based on the geometric data estimated by visual inspection.The results imply that the resonance of the whole structure and the poorer ductility of key members resulted in the collapse of buildings.Finally,some conclusions are drawn.Note that although a large number of buildings were seriously damaged to collapse,the majority of buildings in the areas of extreme shaking were lightly or moderately damaged,which implies that well designed and constructed buildings were able to survive and protect human lives even in over-design earthquakes.

Experimental and Numerical Study on Progressive Collapse Analysis of a Glulam Frame Structure:I.Side Column Exposed to Fire

This paper presents experimental and numerical investigations on progressive collapse behavior of a two-story glulam frame when the side column is exposed to ISO834 standard fire.The collapse mechanism initiated by fire is identified.The experimental results show that the progressive collapse of a glulam frame could be described for three stages,namely bending effect stage,catenary effect stage and failure stage,respectively.These stages are discussed in detail to understand the structural behavior before and during collapse.It is demonstrated that the entire frame slopes towards the side of the heated column,and the“overturning”collapse occurs eventually.The catenary effect of beams is the main reason for the progressive collapse of the frame.In addition,a finite element model of a glulam frame is established to simulate the progressive collapse behavior.The effects of axial loads on the columns are summarized.The numerical simulation results agree well with the experimental results,which could verify the effectiveness and practicability of finite element simulation.Furthermore,the progressive collapse resistance of the frame in practical design were proposed.

Slope Collapse Detection Method Based on Deep Learning Technology

Sofar,slope collapse detectionmainlydepends onmanpower,whichhas the followingdrawbacks:(1)lowreliability,(2)high risk of human safe,(3)high labor cost.To improve the efficiency and reduce the human investment of slope collapse detection,this paper proposes an intelligent detection method based on deep learning technology for the task.In thismethod,we first use the deep learning-based image segmentation technology to find the slope area from the captured scene image.Then the foreground motion detection method is used for detecting the motion of the slope area.Finally,we design a lightweight convolutional neural network with an attentionmechanismto recognize the detected motion object,thus eliminating the interference motion and increasing the detection accuracy rate.Experimental results on the artificial data and relevant scene data show that the proposed detection method can effectively identify the slope collapse,which has its applicative value and brilliant prospect.

Stabilized effects of L-S cement-mixed batter pile composite foundation for existed warm frozen soil subgrade

In permafrost regions with warm frozen soil,subgrade thaw-collapse phenomenon commonly occurs,facing thaw collapse problems of the existed frozen soil subgrade,thus it is difficult to use traditional methods such as active cooling and passive protection technology to stabilize the existed warm frozen soil subgrade.This study derives a novel stabilizer method,a long-short(L-S)cement-mixed batter pile composite foundation to stabilize the existed warm frozen soil subgrade.To solve the thawcollapse problems in warm frozen soil subgrade,high water content and large compressibility characteristics were compared between soft soil and warm frozen soils.Theoretical analysis of heat conduction and numerical simulation of finite element model were used to study the freeze–thaw process and evaluate the stabilized effects of the L-S cement-mixed batter piles on the warm frozen soil foundation of the Qinghai-Tibet Highway.Furthermore,the thaw process and mechanical properties of foundation and piles were analyzed by introducing the hydration heat factor in the thermodynamic control equation.The results indicate that the thawing displacement of the existed warm frozen soil subgrade was reduced owing to the“support”and“grasp”effects of the L-S cement-mixed batter piles on the surrounding soil.The composite ground formed by strengthening the warm frozen ground with batter piles could considerably improve the bearing capacity of the existed warm frozen ground,effectively restrain the deformation of the upper embankment,and improve the strength of the ground.The analysis can provide method for the construction design of cement mixing batter pile foundation in cold regions.

A dynamic large-deformation particle finite element method for geotechnical applications based on Abaqus

In this paper,the application of Abaqus-based particle finite element method(PFEM)is extended from static to dynamic large deformation.The PFEM is based on periodic mesh regeneration with Delaunay triangulation to avoid mesh distortion.Additional mesh smoothing and boundary node smoothing techniques are incorporated to improve the mesh quality and solution accuracy.The field variables are mapped from the old to the new mesh using the closest point projection method to minimize the mapping error.The procedures of the proposed Abaqus-based dynamic PFEM(Abaqus-DPFEM)analysis and its implementation in Abaqus are detailed.The accuracy and robustness of the proposed approach are examined via four illustrative numerical examples.The numerical results show a satisfactory agreement with published results and further confirm the applicability of the Abaqus-DPFEM to solving dynamic large-deformation problems in geotechnical engineering.