Lysophosphatidic acid(LPA)is a pleiotropic lipid agonist essential for functions of the central nervous system(CNS).It is abundant in the developing and adult brain while its concentration in biological fluids,includi...Lysophosphatidic acid(LPA)is a pleiotropic lipid agonist essential for functions of the central nervous system(CNS).It is abundant in the developing and adult brain while its concentration in biological fluids,including cerebrospinal fluid,varies significantly(Figure 1Α;Yung et al.,2014).LPA actually corresponds to a variety of lipid species that include different stereoisomers with either saturated or unsaturated fatty acids bearing likely differentiated biological activities(Figure 1Α;Yung et al.,2014;Hernández-Araiza et al.,2018).展开更多
This paper investigated the use of magnesium phosphate cement (MPC) for solidifying sludge with different humic acid (HA) content (ranging from 0 to 4.5%) and explored the solidification mechanism. Fluidity, setting t...This paper investigated the use of magnesium phosphate cement (MPC) for solidifying sludge with different humic acid (HA) content (ranging from 0 to 4.5%) and explored the solidification mechanism. Fluidity, setting time, unconfined compressive strength (UCS), the strength formation mechanism, and the spontaneous imbibition process of solidified sludge (SS) were studied. The results indicate that MPC can be used as a low-alkalinity curing agent. As the HA content increases, fluidity and setting time also increase, while hydration temperature and strength decrease. Additionally, the failure mode of SS transitions from brittleness to ductility. The strength of SS is composed of the cementation strength provided by MPC hydration products, matric suction, osmotic suction, and the structural strength of the sludge. MPC reduces the structural strength caused by the shrinkage of pure sludge under the action of matric suction, but the incorporation of MPC significantly improved the strength when the sludge is eroded by water. X-ray diffraction (XRD) and scanning electron microscopy (SEM) show that the sludge and MPC can form a dense solid body, forming various hydration products, and synergistically improve the mechanical properties of the sludge.展开更多
Although time-dependent deformation of geomaterials underpins slope-failure prediction models,the influence of strain rate on shearing strength and deformation behavior of loess remains unclear.The consolidated undrai...Although time-dependent deformation of geomaterials underpins slope-failure prediction models,the influence of strain rate on shearing strength and deformation behavior of loess remains unclear.The consolidated undrained(CU)and drained(CD)triaxial testing elucidated the impact of strain rate(0.005–0.3 mm/min)on strength envelopes,deformation moduli,pore pressures,and dilatancy characteristics of unsaturated and quasi-saturated loess.Under drained conditions with a controlled matric suction of 50 kPa,increasing strain rates from 0.005 mm/min to 0.011 mm/min induced decreases in failure deviatoric stress(qf),initial deformation modulus(Ei),and cohesion(c),while friction angles remained unaffected.Specimens displayed initial contractive volumetric strains transitioning to dilation across varying confining pressures.Higher rates diminished contractive volumetric strains and drainage volumes,indicating reduced densification and strength in the shear zone.Under undrained conditions,both unsaturated and quasi-saturated(pore pressure coefficient B=0.75)loess exhibited deteriorating mechanical properties with increasing rates from 0.03 mm/min to 0.3 mm/min.For unsaturated loess,reduced contractive volumetric strains at higher rates manifested relatively looser structures in the pre-peak stress phase.The strength decrement in quasi-saturated loess arose from elevated excess porewater pressures diminishing effective stresses.Negative porewater pressures emerged in quasi-saturated loess at lower confining pressures and strain rates.Compared to previous studies,the qf and Ei exhibited rate sensitivity below threshold values before attaining minima with marginal subsequent influence.The underlying mechanism mirrors the transition from creep to accelerated deformation phase of landslides.展开更多
Evaluation of hydromechanical shear behavior of unsaturated soils is still a challenging issue. The time and cost needed for conducting precise experimental investigation on shear behavior of unsaturated soils have en...Evaluation of hydromechanical shear behavior of unsaturated soils is still a challenging issue. The time and cost needed for conducting precise experimental investigation on shear behavior of unsaturated soils have encouraged several investigators to develop analytical, empirical, or semi-empirical models for predicting the shear behavior of unsaturated soils. However, most of the previously proposed models are for specimens subjected to the isotropic state of stress, without considering the effect of initial shear stress. In this study, a hydromechanical constitutive model is proposed for unsaturated collapsible soils during shearing, with consideration of the effect of the initial shear stress. The model implements an effective stress-based disturbed state concept (DSC) to predict the stress-strain behavior of the soil. Accordingly, material/state variables were defined for both the start of the shearing stage and the critical state of the soil. A series of laboratory tests was performed using a fully automated unsaturated triaxial device to verify the proposed model. The experimental program included 23 suction-controlled unsaturated triaxial shear tests on reconstituted specimens of Gorgan clayey loess wetted to different levels of suctions under both isotropic and anisotropic stress states. The results show excellent agreement between the prediction by the proposed model and the experimental results.展开更多
Epidemiological evidence suggests that there is a direct relationship between the degree of obesity and acute pancreatitis severity.Intake of different fatty acids leads to different types of hyperlipidemias.Adipose d...Epidemiological evidence suggests that there is a direct relationship between the degree of obesity and acute pancreatitis severity.Intake of different fatty acids leads to different types of hyperlipidemias.Adipose degradation by pancreatic lipase generates different free fatty acids,which can exacerbate pancreatitis.Saturated fatty acids(SFAs)play an inflammatory role in human metabolic syndrome and obesity,whereas unsaturated fatty acids(UFAs)are“good fats”that are thought to enhance overall health status.However,it appears that serum UFAs correlate with severe acute pancreatitis.Additionally,the“obesity paradox”suggests that UFAs potentially minimize direct harm to the organ.This review provides an in-depth overview of the role of SFAs and UFAs in acute pancreatitis of hyperlipidemia and discusses potential prevention targets for severe acute pancreatitis.展开更多
The deformation characteristics of silty soils under vibrational loads can easily change due to the wetting process,leading to the failure of roadbed structures.Commonly used methods for improving silty soils in engin...The deformation characteristics of silty soils under vibrational loads can easily change due to the wetting process,leading to the failure of roadbed structures.Commonly used methods for improving silty soils in engineering often yield unsatisfactory economic and ecological outcomes.As an environment-friendly soil improvement material,Xanthan gum has broad application prospects and is therefore considered a solidifying agent for enhancing silty soil properties in the Yellow River Basin.In this study,a series of tests is conducted using a scanning electron microscope and a dynamic triaxial testing apparatus to investigate the microstructure and dynamic deformation characteristics of unsaturated silty soil with varying xanthan gum contents during the wetting process.The results show that xanthan gum effectively fills voids between soil particles and adheres to their surfaces,forming fibrous and network structures.This modification enhances the inherent properties of the silty soil and significantly improves its stability under dynamic loading.Specifically,with increasing xanthan gum content,the dynamic shear modulus increases while the damping ratio decreases.During the wetting process,as suction decreases,the dynamic shear modulus decreases while the damping ratio increases.Xanthan gum reduces the sensitivity of the dynamic deformation characteristics of the treated silty soil to changes in suction levels.Finally,based on the modified Hardin-Drnevich hyperbolic model,a predictive model for the dynamic shear modulus and damping ratio of treated silty soil is proposed,considering the xanthan gum content.These research findings provide a theoretical basis for the construction and maintenance of water conservancy,slope stabilization,and roadbed projects in the Yellow River Basin.展开更多
Difunctionalization of unsaturated hydrocarbons is a pivotal synthetic strategy enabling the conversion of alkenes and alkynes into high value-added compounds.It allows for the introduction of two functional groups in...Difunctionalization of unsaturated hydrocarbons is a pivotal synthetic strategy enabling the conversion of alkenes and alkynes into high value-added compounds.It allows for the introduction of two functional groups into the unsaturated bond in a single step,facilitating the efficient construction of complex molecular architectures,which has been widely utilized in material chemistry,pharmaceutical and fine chemical synthesis.Recently,significant progress has been made via free radical-mediated difunctionalization due to the extensive application of photocatalysis.However,highly selective difunc-tionalization reactions still remain challenging.The research progress of selective difunctionalization of unsaturated hydro-carbons using a free radical addition/functional group migration strategy over the past decade is summarized,and synthetic strategies and key reaction steps are systematically elaborated.展开更多
Propane dehydrogenation(PDH)has emerged as a key on-purpose technology for the production of propylene,but it often depends on toxic chromium and expensive platinum catalysts,highlighting the need for environmentally ...Propane dehydrogenation(PDH)has emerged as a key on-purpose technology for the production of propylene,but it often depends on toxic chromium and expensive platinum catalysts,highlighting the need for environmentally friendly and cost-effective alternatives.In this study,we developed a facile impregnation method to fabricate unsaturated Co single-atoms with a tricoordinated Co_(1)O_(3)H_(x) structure by regulating silanol nests in purely siliceous Beta zeolites.Detailed PDH catalytic tests and characterizations revealed a positive correlation between the presence of silanol nests and enhanced catalytic activity.Additionally,the unsaturated Co single-atoms exhibited a carbon deposition rate more than an order of magnitude slower than that of Co nanoparticles.Notably,the optimized Co_(0.3%)/deAl-meso-Beta catalyst achieved a record-high propylene formation rate of 21.2 mmol_(C3H6) g_(cat)^(-1) h^(-1),with an exceptional propylene selectivity of 99.1%at 550℃.Moreover,the Co_(0.3%)/deAl-meso-Beta catalyst demonstrated excellent stability,with negligible deactivation after 5 consecutive regeneration cycles.This study emphasizes the pivotal role of silanol nests of zeolites in stabilizing and modulating the coordination environment of metallic active sites,providing valuable insights for the design of high-activity,high-stability,and low-cost PDH catalysts.展开更多
Selective oxidation of olefin to epoxides is an important reaction in industry,however,developing heterogeneous catalysts to achieve the effective catalysis for this reaction under O_(2)atmosphere at room temperature ...Selective oxidation of olefin to epoxides is an important reaction in industry,however,developing heterogeneous catalysts to achieve the effective catalysis for this reaction under O_(2)atmosphere at room temperature is challenging but highly desired.In this work,two novel 2D cobalt metal-organic complexes,namely[Co(L)(5-HIP)]·2H_(2)O(Co-MOC-1)and[Co(L)(BTEC)_(0.5)]·H_(2)O(Co-MOC-2)(L=(E)-4,4-(ethene-1,2-diyl))bis(N-(pyridin-3-yl)benzamide;5-H_(2)HIP=5-hydroxyisophthalic acid;H4BTEC=pyromellitic acid)were designed and synthesized through hydrothermal method,which exhibited different metal coordination modes(4-coordinate and 5-coordinate,respectively)and 2D layer structures directed by different carboxylates co-ligands.Two Co-MOCs can serve as heterogeneous catalysts for the selective oxidation of olefins to epoxides at room temperature using O_(2)as oxidant.Furthermore,a higher catalysis activity of Co-MOC-1 than Co-MOC-2(96.7%vs.90.2%yield of 1,2-epoxycyclooctane)was observed,which may be attributed to the coordination unsaturated Co centers,the less coordination number and larger interlayer spacing of Co-MOC-1.展开更多
The effectiveness of using vegetation to stabilise shallow soil slopes heavily depends on the survival of vegetation,yet the amplification of extreme events induced by climate change threatens the health of plants cov...The effectiveness of using vegetation to stabilise shallow soil slopes heavily depends on the survival of vegetation,yet the amplification of extreme events induced by climate change threatens the health of plants covering slopes.Hydrochar is an environmentally friendly soil amender that can achieve the potential benefits of promoting plant growth for slope stabilisation and facilitation of waste upcycling.The mechanism underlying the hydrochar effects on the mechanical behaviour of unsaturated soils remains unclear.This study investigated the influence of grass-derived hydrochar on the water retention,compressibility,and shear strength of a compacted siltyeclay sand.Soil microstructural changes due to hydrochar amendment were measured to explain the soilehydrochar hydromechanical interaction.The increase in suction resulted in a less significant increase in yield stress and a negligible reduction in compressibility of the hydrochar-amended soil compared with the unamended case.This phenomenon was observed because hydrochar addition reduced the large pores with diameters greater than the macropore peak of 60 mm due to pore filling by hydrochar particles,resulting in a less substantial volume contraction during drying.Hydrochar introduced more significant effects on the soil’s shear strength in an unsaturated state compared to a saturated case.Despite the similarity of the unsaturated amended soil with the critical-state friction angle to the saturated case,the former exhibited a greater shear strength because the hydrochar addition improved water retention capability.As a result,the degree of saturation and,hence,Bishop’s effective stress were higher than those for the unamended case for a given suction.展开更多
A series of suction-controlled triaxial tests was conducted on Nanyang expansive clay to investigate the effects of dry density and suction on dilatancy and strength.The suction of the soil samples was controlled usin...A series of suction-controlled triaxial tests was conducted on Nanyang expansive clay to investigate the effects of dry density and suction on dilatancy and strength.The suction of the soil samples was controlled using a vapour equilibrium technique,with four suction levels ranging from 3.29 MPa to 198.14 MPa,where water retention is dominated by adsorption.The experimental results show that the tested soil exhibits a brittle failure mode under high suction,significantly distinguishing the hydro-mechanical behaviour of the soil at high suction from that observed at low suction.This brittle failure mode significantly increases the contribution of suction to peak strength compared to residual strength,causes the soil to fail before reaching the critical state,a phenomenon not observed in soils under high suction,and results in dilatancy caused by damage to the soil particle aggregates rather than particle rearrangement.The dilatancy data obtained from the triaxial tests reveal that significant soil dilatancy occurs during shear after reaching peak strength,with the maximum dilatancy angle increasing with suction and decreasing with confining pressure.However,the initial dry density has a negligible impact on the soil's dilatancy under high suction levels.This observation further supports that,for unsaturated soils under high suction levels,dilatancy is attributed to damage to soil particle aggregates rather than the rearrangement of soil particles.展开更多
Narrow backfill earth pressure estimation is applied to study the stability of supporting structures in the vicinity of existing buildings.Previous narrow backfill earth pressure studies have neglected seismic-unsatur...Narrow backfill earth pressure estimation is applied to study the stability of supporting structures in the vicinity of existing buildings.Previous narrow backfill earth pressure studies have neglected seismic-unsaturated seepage multi-field coupling,resulting in inaccurate estimates.To address these deficiencies,this paper proposed a calculation method for seismic passive earth pressure in unsaturated narrow backfill,based on inclined thin-layer units.It considers the interlayer shear stress,arching effect,and the multi-field coupling of seismic-unsaturated seepage.Additionally,this paper includes a parametric sensitivity analysis.The outcomes indicate that the earthquake passive ground pressure of unsaturated narrow backfill can be reduced by increasing the aspect ratio,seismic acceleration coefficient,and unsaturation parameterα.It can also be reduced by decreasing the effective interior friction angle,soil cohesion,wallearth friction angle,and vertical discharge.Furthermore,for any width soil,lowering the elevation of the action point of passive thrust can be attained by raising the effective interior friction angle,wall-earth friction angle,and unsaturation parameterα.Reducing soil cohesion,seismic acceleration coefficient,and vertical discharge can also lower the height of the application point of passive thrust.展开更多
The engineering diseases caused by seasonal sulfate saline soil in Hexi region of Gansu Province seriously affect the local infrastructure construction and operation maintenance.To address this issue,this study explor...The engineering diseases caused by seasonal sulfate saline soil in Hexi region of Gansu Province seriously affect the local infrastructure construction and operation maintenance.To address this issue,this study explored the thermal mass transfer law,pore fluid phase transition,soil deformation and microstructure of unsaturated sulfate saline soil under the open system.Firstly,based on the theories of porous media mechanics and continuum mechanics,combined with the conservation equations of mass,energy and momentum and considering the phase transition of pore fluid,a multi-field coupled mathematical model of hydro-thermal-salt-gasmechanical for unsaturated sulfate saline soil was established.Secondly,basic unknown variables such as pore water pressure,concentration,temperature,porosity,and displacement were selected to perform numerical simulation analysis on the equation system by“Comsol Multiphysics”finite element method.Finally,a comparative analysis was conducted between the on-site measured data and the numerical simulation results.The results show that the water and salt phase transitions caused by temperature change could lead to soil salt heave and frost heave,alter the pore structure of the soil,and reduce the compactness of the soil,ultimately being reflected in the changes in soil porosity.The influence of external temperature on soil temperature gradually decreases with increasing depth,and the sensitivity of frozen areas to external temperature is much higher than that of unfrozen areas.This study not only enriches the theoretical results of thermal mass transfer law and deformation of unsaturated sulfate saline soil,but also provides practical guidance for the prevention and control of engineering diseases in local sulfate saline soil.展开更多
Loess is susceptible to loading effects such as significant changes in strength and volume variation caused by loading and wetting.In this study,considering the different connection states of pore water and gas in loe...Loess is susceptible to loading effects such as significant changes in strength and volume variation caused by loading and wetting.In this study,considering the different connection states of pore water and gas in loess fabric,the gas phase closure case is incorporated into a unified form of the generalized effective stress framework,introducing a damage parameter considering the effects of closed pore gas.The loading effects of unsaturated loess under wide variations in saturation are described in a unified way,and the model performance is verified by corresponding stress and hydraulic path tests.The results indicated that the collapse response involves the initial void ratio of loess,and the coupled outwards motion of the loading-collapse(LC)yield surface under loading enhances its structural strength.Suction-enhanced yield stress requires a greater"tensile stress"to counteract its structural stability.The nucleation of bubbles at high saturation causes a decrease in yield stress.The loading effect exhibits a smaller collapse behavior when the influence of closed gas is considered,whereas the suction path does not cross the LC in the stress space under hydraulic action for the same parameters,which amplifies the influence of closed gas on loess deformation.展开更多
Compaction grouting is primarily applied based on empiricism,and it is challenging to quantify its densification effect.To address this issue,five sets of laboratory model tests on ideal compaction grouting were condu...Compaction grouting is primarily applied based on empiricism,and it is challenging to quantify its densification effect.To address this issue,five sets of laboratory model tests on ideal compaction grouting were conducted,with varying pressures from 400 kPa to 800 kPa,to quantitatively evaluate the densification effect in unsaturated soils.The response of surrounding soil during compaction grouting was monitored.The changes in dry density and void ratio induced by compaction grouting were obtained by monitoring volumetric water content to determine compaction efficiency.In addition,a model was developed and validated to predict the effective compaction range.The results show that soil dry density increased rapidly during compaction grouting before being stabilized at a consistent level.As expected,it is positively correlated with grouting pressures(GPs)and negatively correlated with the distance from the injection point.At higher GPs,the difference in densification effect around the injection point after compaction grouting was significant.Interestingly,variations in ultimate dry density and peak earth pressures perpendicular to the injection direction exhibited axisymmetric behavior around the injection point when comparing the dry density and earth pressure results.Furthermore,soil densification resulted in a decrease in suction.However,no significant effect of GP on suction at different soil positions was observed.Moreover,compaction efficiency decreased with increasing distance from the injection point,showing a strong linear relationship.In addition,the model results for the effective compaction range were basically consistent with the extrapolated values from the experimental results.展开更多
A simplified analytical approach is proposed for predicting the load-displacement behavior of single piles in unsaturated soils considering the contribution from the nonlinear shear strength and soil stiffness influen...A simplified analytical approach is proposed for predicting the load-displacement behavior of single piles in unsaturated soils considering the contribution from the nonlinear shear strength and soil stiffness influenced by matric suction.This approach includes a Modified Load Transfer Model(MLTM)that can predict the nonlinear relationships between the shear stress and pile-soil relative displacement along the pile shaft,and between the pile base resistance and base settlement.The proposed model is also extended for pile groups to incorporate the interaction effects between individual piles.The analytical approach is validated through a comparative analysis with the measurements from two single pile tests and one pile group test.In addition,a finite element analysis using 3D modeling is carried out to investigate the behavior of pile groups in various unsaturated conditions.This is accomplished with a user-defined subroutine that is written and implemented in ABAQUS to simulate the nonlinear mechanical behavior of unsaturated soils.The predictions derived from the proposed analytical and numerical methods compare well with the measurements of a published experimental study.The proposed methodologies have the potential to be applied in geotechnical engineering practice for the rational design of single piles and pile groups in unsaturated soils.展开更多
The selective addition reaction of unsaturated C-C bonds has always been a classic and constant research topic.Different from well-developed hydroboration,hydrosilylation,and hydrostannylation reaction,hydrogermylatio...The selective addition reaction of unsaturated C-C bonds has always been a classic and constant research topic.Different from well-developed hydroboration,hydrosilylation,and hydrostannylation reaction,hydrogermylation reaction remains challenging which hasn't been much reported.Herein,we developed a new metal-porous ligand polymers Pd1@POL-PPh_(n)Cy_(m)(n+m=3)with monoatomic dispersion characteristics for highly selective and efficient hydrogermylation of unsaturated C-C bonds,including alkynes,alkenes,and allenes.X-ray photoelectron spectroscopy and theoretical calculations further proved the introduction of cyclohexyl could gently adjust the charge on monoatomic Pd center which effectively facilitate the recognition and transformation of various substrates.With the electrically fine-tuned single atom palladium catalysts,we realized theα-germanium addition for the first time,obtaining corresponding allyl germanium and alkyl germanium compounds.展开更多
Unsaturated alcohols are a class of Biogenic volatile organic compounds(BVOCs)emitted in large quantities by plants when damaged or under adverse environmental conditions,and studies on their atmospheric degradation a...Unsaturated alcohols are a class of Biogenic volatile organic compounds(BVOCs)emitted in large quantities by plants when damaged or under adverse environmental conditions,and studies on their atmospheric degradation at night are still lacking.We used chamber experiments to study the gas-phase reactions of three unsaturated alcohols,E-2-penten-1-ol,Z-2-hexen-1-ol and Z-3-hepten-1-ol,with NO_(3)radicals(NO_(3)•)during the night.The rate constants of these reactions were(11.7±1.76)×10^(−13),(8.55±1.33)×10^(−13)and(6.08±0.47)×10^(−13)cm^(3)/(molecule·s)at 298K and 760 Torr,respectively.In contrast,the reaction rate of similar substances with ozone was about 10^(−18)cm^(3)/(molecule·s),which indicates that the reaction with NO_(3)•is themain oxidation pathway for unsaturated alcohols at night.Small molecule aldehydes and ketones were the main gas-phase organic products of the reaction of three aldehydes and ketones with NO_(3)•,and the total small molecule aldehydes and ketones yields can reach between 45%-60%.They mainly originate from the breakage of alkoxy radicals,and different breakage sites determine different product distributions.In addition,the SOA yields of the three unsaturated alcohols with NO_(3)•were 7.1%±1.0%,12.5%±1.9%and 30.0%±4.5%,respectively,whichweremuch higher than those of similarly structured substances with O_(3)or OH radicals(•OH).The results of high-resolution mass spectrometry shows that the main components of Secondary organic aerosol(SOA)of the three unsaturated alcohols are dimeric compounds containing several nitrate groups,which are formed through the polymerization of oxyalkyl radicals.展开更多
This study presents a fully coupled thermo-hydro-mechanical (THM) constitutive model for clay rocks. The model is formulated within the elastic-viscoplasticity framework, which considers nonlinearity and softening aft...This study presents a fully coupled thermo-hydro-mechanical (THM) constitutive model for clay rocks. The model is formulated within the elastic-viscoplasticity framework, which considers nonlinearity and softening after peak strength, anisotropy of stiffness and strength, as well as permeability variation due to damage. In addition, the mechanical properties are coupled with thermal phenomena and accumulated plastic strains. The adopted nonlocal and viscoplastic approaches enhance numerical efficiency and provide the possibility to simulate localization phenomena. The model is validated against experimental data from laboratory tests conducted on Callovo-Oxfordian (COx) claystone samples that are initially unsaturated and under suction. The tests include a thermal phase where the COx specimens are subjected to different temperature increases. A good agreement with experimental data is obtained. In addition, parametric analyses are carried out to investigate the influence of the hydraulic boundary conditions (B.C.) and post-failure behavior models on the THM behavior evolution. It is shown that different drainage conditions affect the thermally induced pore pressures that, in turn, influence the onset of softening. The constitutive model presented constitutes a promising approach for simulating the most important features of the THM behavior of clay rocks. It is a tool with a high potential for application to several relevant case studies, such as thermal fracturing analysis of nuclear waste disposal systems.展开更多
Unsaturated soil mechanics is crucial in understanding ground conditions and constructing geotechnical structures,particularly amidst the challenges posed by global climate change.Nevertheless,acquiring accurate soil ...Unsaturated soil mechanics is crucial in understanding ground conditions and constructing geotechnical structures,particularly amidst the challenges posed by global climate change.Nevertheless,acquiring accurate soil suction values remains challenging due to limitations in existing methodologies,such as susceptibility to cavitation,high costs,and time-intensive procedures.Hence,this study employs a high-suction polymer sensor(HSPS)to evaluate the polymer's performance in determining soil suction.Subsequently,the polymers were used to measure unsaturated soil properties,especially soil-water characteristics curves(SWCC),based on osmotic principles.Five polymer samples classified as superabsorbent polymers(SAP)were synthesized with varying degrees of crosslinking,and their properties were assessed through swelling test and Fourier-transform infrared spectroscopy(FTIR).The soil sample from Turan,located within Nazarbayev University,was analyzed using a bimodal equation to determine the best fit.Results revealed that the swelling value and structural integrity of the polymer significantly affect soil suction capacity,with the findings being deemed temperature-independent,thereby obviating the need for calibration.Two potential factors hindering suction increase were identified:cavitation within the polymer or a reduction in the osmotic gradient due to polymer transformation into hydrogel formation.Overall,the novel polymer shows promise as an alternate material for SWCC measurement considering its simple method and being more sustainable compared to the other polymers,although further investigation is required to enhance the suction potential.展开更多
基金supported by the Hellenic Foundation for Research and Innovation,HFRI,“2nd Call for HFRI Research Projects to support Faculty Members&Researchers”Project 02667 to GL.
文摘Lysophosphatidic acid(LPA)is a pleiotropic lipid agonist essential for functions of the central nervous system(CNS).It is abundant in the developing and adult brain while its concentration in biological fluids,including cerebrospinal fluid,varies significantly(Figure 1Α;Yung et al.,2014).LPA actually corresponds to a variety of lipid species that include different stereoisomers with either saturated or unsaturated fatty acids bearing likely differentiated biological activities(Figure 1Α;Yung et al.,2014;Hernández-Araiza et al.,2018).
基金This research work was financially supported by the National Natural Science Foundation of China(Grant No.51972209).
文摘This paper investigated the use of magnesium phosphate cement (MPC) for solidifying sludge with different humic acid (HA) content (ranging from 0 to 4.5%) and explored the solidification mechanism. Fluidity, setting time, unconfined compressive strength (UCS), the strength formation mechanism, and the spontaneous imbibition process of solidified sludge (SS) were studied. The results indicate that MPC can be used as a low-alkalinity curing agent. As the HA content increases, fluidity and setting time also increase, while hydration temperature and strength decrease. Additionally, the failure mode of SS transitions from brittleness to ductility. The strength of SS is composed of the cementation strength provided by MPC hydration products, matric suction, osmotic suction, and the structural strength of the sludge. MPC reduces the structural strength caused by the shrinkage of pure sludge under the action of matric suction, but the incorporation of MPC significantly improved the strength when the sludge is eroded by water. X-ray diffraction (XRD) and scanning electron microscopy (SEM) show that the sludge and MPC can form a dense solid body, forming various hydration products, and synergistically improve the mechanical properties of the sludge.
文摘Although time-dependent deformation of geomaterials underpins slope-failure prediction models,the influence of strain rate on shearing strength and deformation behavior of loess remains unclear.The consolidated undrained(CU)and drained(CD)triaxial testing elucidated the impact of strain rate(0.005–0.3 mm/min)on strength envelopes,deformation moduli,pore pressures,and dilatancy characteristics of unsaturated and quasi-saturated loess.Under drained conditions with a controlled matric suction of 50 kPa,increasing strain rates from 0.005 mm/min to 0.011 mm/min induced decreases in failure deviatoric stress(qf),initial deformation modulus(Ei),and cohesion(c),while friction angles remained unaffected.Specimens displayed initial contractive volumetric strains transitioning to dilation across varying confining pressures.Higher rates diminished contractive volumetric strains and drainage volumes,indicating reduced densification and strength in the shear zone.Under undrained conditions,both unsaturated and quasi-saturated(pore pressure coefficient B=0.75)loess exhibited deteriorating mechanical properties with increasing rates from 0.03 mm/min to 0.3 mm/min.For unsaturated loess,reduced contractive volumetric strains at higher rates manifested relatively looser structures in the pre-peak stress phase.The strength decrement in quasi-saturated loess arose from elevated excess porewater pressures diminishing effective stresses.Negative porewater pressures emerged in quasi-saturated loess at lower confining pressures and strain rates.Compared to previous studies,the qf and Ei exhibited rate sensitivity below threshold values before attaining minima with marginal subsequent influence.The underlying mechanism mirrors the transition from creep to accelerated deformation phase of landslides.
文摘Evaluation of hydromechanical shear behavior of unsaturated soils is still a challenging issue. The time and cost needed for conducting precise experimental investigation on shear behavior of unsaturated soils have encouraged several investigators to develop analytical, empirical, or semi-empirical models for predicting the shear behavior of unsaturated soils. However, most of the previously proposed models are for specimens subjected to the isotropic state of stress, without considering the effect of initial shear stress. In this study, a hydromechanical constitutive model is proposed for unsaturated collapsible soils during shearing, with consideration of the effect of the initial shear stress. The model implements an effective stress-based disturbed state concept (DSC) to predict the stress-strain behavior of the soil. Accordingly, material/state variables were defined for both the start of the shearing stage and the critical state of the soil. A series of laboratory tests was performed using a fully automated unsaturated triaxial device to verify the proposed model. The experimental program included 23 suction-controlled unsaturated triaxial shear tests on reconstituted specimens of Gorgan clayey loess wetted to different levels of suctions under both isotropic and anisotropic stress states. The results show excellent agreement between the prediction by the proposed model and the experimental results.
文摘Epidemiological evidence suggests that there is a direct relationship between the degree of obesity and acute pancreatitis severity.Intake of different fatty acids leads to different types of hyperlipidemias.Adipose degradation by pancreatic lipase generates different free fatty acids,which can exacerbate pancreatitis.Saturated fatty acids(SFAs)play an inflammatory role in human metabolic syndrome and obesity,whereas unsaturated fatty acids(UFAs)are“good fats”that are thought to enhance overall health status.However,it appears that serum UFAs correlate with severe acute pancreatitis.Additionally,the“obesity paradox”suggests that UFAs potentially minimize direct harm to the organ.This review provides an in-depth overview of the role of SFAs and UFAs in acute pancreatitis of hyperlipidemia and discusses potential prevention targets for severe acute pancreatitis.
基金supported by the Postgraduate Education Reform and Quality Improvement Project of Henan Province,China(Grant No.YJS2023AL004)the Graduate Innovation Project of North China University of Water Resources and Electric Power(Grant No.NCWUYC-202315069)the China National Scholarship Fund organized by the China Scholarship Council(Grant No.202208410337).
文摘The deformation characteristics of silty soils under vibrational loads can easily change due to the wetting process,leading to the failure of roadbed structures.Commonly used methods for improving silty soils in engineering often yield unsatisfactory economic and ecological outcomes.As an environment-friendly soil improvement material,Xanthan gum has broad application prospects and is therefore considered a solidifying agent for enhancing silty soil properties in the Yellow River Basin.In this study,a series of tests is conducted using a scanning electron microscope and a dynamic triaxial testing apparatus to investigate the microstructure and dynamic deformation characteristics of unsaturated silty soil with varying xanthan gum contents during the wetting process.The results show that xanthan gum effectively fills voids between soil particles and adheres to their surfaces,forming fibrous and network structures.This modification enhances the inherent properties of the silty soil and significantly improves its stability under dynamic loading.Specifically,with increasing xanthan gum content,the dynamic shear modulus increases while the damping ratio decreases.During the wetting process,as suction decreases,the dynamic shear modulus decreases while the damping ratio increases.Xanthan gum reduces the sensitivity of the dynamic deformation characteristics of the treated silty soil to changes in suction levels.Finally,based on the modified Hardin-Drnevich hyperbolic model,a predictive model for the dynamic shear modulus and damping ratio of treated silty soil is proposed,considering the xanthan gum content.These research findings provide a theoretical basis for the construction and maintenance of water conservancy,slope stabilization,and roadbed projects in the Yellow River Basin.
文摘Difunctionalization of unsaturated hydrocarbons is a pivotal synthetic strategy enabling the conversion of alkenes and alkynes into high value-added compounds.It allows for the introduction of two functional groups into the unsaturated bond in a single step,facilitating the efficient construction of complex molecular architectures,which has been widely utilized in material chemistry,pharmaceutical and fine chemical synthesis.Recently,significant progress has been made via free radical-mediated difunctionalization due to the extensive application of photocatalysis.However,highly selective difunc-tionalization reactions still remain challenging.The research progress of selective difunctionalization of unsaturated hydro-carbons using a free radical addition/functional group migration strategy over the past decade is summarized,and synthetic strategies and key reaction steps are systematically elaborated.
文摘Propane dehydrogenation(PDH)has emerged as a key on-purpose technology for the production of propylene,but it often depends on toxic chromium and expensive platinum catalysts,highlighting the need for environmentally friendly and cost-effective alternatives.In this study,we developed a facile impregnation method to fabricate unsaturated Co single-atoms with a tricoordinated Co_(1)O_(3)H_(x) structure by regulating silanol nests in purely siliceous Beta zeolites.Detailed PDH catalytic tests and characterizations revealed a positive correlation between the presence of silanol nests and enhanced catalytic activity.Additionally,the unsaturated Co single-atoms exhibited a carbon deposition rate more than an order of magnitude slower than that of Co nanoparticles.Notably,the optimized Co_(0.3%)/deAl-meso-Beta catalyst achieved a record-high propylene formation rate of 21.2 mmol_(C3H6) g_(cat)^(-1) h^(-1),with an exceptional propylene selectivity of 99.1%at 550℃.Moreover,the Co_(0.3%)/deAl-meso-Beta catalyst demonstrated excellent stability,with negligible deactivation after 5 consecutive regeneration cycles.This study emphasizes the pivotal role of silanol nests of zeolites in stabilizing and modulating the coordination environment of metallic active sites,providing valuable insights for the design of high-activity,high-stability,and low-cost PDH catalysts.
基金financially supported by the National Natural Science Foundation of China(Nos.22271021,21971024,22201021)the Doctoral Scientific Research Foundation of Liaoning Province(No.2022-BS-302)。
文摘Selective oxidation of olefin to epoxides is an important reaction in industry,however,developing heterogeneous catalysts to achieve the effective catalysis for this reaction under O_(2)atmosphere at room temperature is challenging but highly desired.In this work,two novel 2D cobalt metal-organic complexes,namely[Co(L)(5-HIP)]·2H_(2)O(Co-MOC-1)and[Co(L)(BTEC)_(0.5)]·H_(2)O(Co-MOC-2)(L=(E)-4,4-(ethene-1,2-diyl))bis(N-(pyridin-3-yl)benzamide;5-H_(2)HIP=5-hydroxyisophthalic acid;H4BTEC=pyromellitic acid)were designed and synthesized through hydrothermal method,which exhibited different metal coordination modes(4-coordinate and 5-coordinate,respectively)and 2D layer structures directed by different carboxylates co-ligands.Two Co-MOCs can serve as heterogeneous catalysts for the selective oxidation of olefins to epoxides at room temperature using O_(2)as oxidant.Furthermore,a higher catalysis activity of Co-MOC-1 than Co-MOC-2(96.7%vs.90.2%yield of 1,2-epoxycyclooctane)was observed,which may be attributed to the coordination unsaturated Co centers,the less coordination number and larger interlayer spacing of Co-MOC-1.
基金supported by grants funded by the Hong Kong Research Grants Council(Grant No.CRF/C6006-20G)a grant provided by the Joint NSFC/RGC Joint Research Scheme(Grant No.N_HKUST603/22)the Fundamental Research Funds for the Central Universities(Grant No.Z1090125018).
文摘The effectiveness of using vegetation to stabilise shallow soil slopes heavily depends on the survival of vegetation,yet the amplification of extreme events induced by climate change threatens the health of plants covering slopes.Hydrochar is an environmentally friendly soil amender that can achieve the potential benefits of promoting plant growth for slope stabilisation and facilitation of waste upcycling.The mechanism underlying the hydrochar effects on the mechanical behaviour of unsaturated soils remains unclear.This study investigated the influence of grass-derived hydrochar on the water retention,compressibility,and shear strength of a compacted siltyeclay sand.Soil microstructural changes due to hydrochar amendment were measured to explain the soilehydrochar hydromechanical interaction.The increase in suction resulted in a less significant increase in yield stress and a negligible reduction in compressibility of the hydrochar-amended soil compared with the unamended case.This phenomenon was observed because hydrochar addition reduced the large pores with diameters greater than the macropore peak of 60 mm due to pore filling by hydrochar particles,resulting in a less substantial volume contraction during drying.Hydrochar introduced more significant effects on the soil’s shear strength in an unsaturated state compared to a saturated case.Despite the similarity of the unsaturated amended soil with the critical-state friction angle to the saturated case,the former exhibited a greater shear strength because the hydrochar addition improved water retention capability.As a result,the degree of saturation and,hence,Bishop’s effective stress were higher than those for the unamended case for a given suction.
基金support from the China Scholarship Council(CSC)-University of Technology Sydney joint scholarship and the National Key R&D Program of China(Grant No.2016YFC0800200)is gratefully acknowledged.
文摘A series of suction-controlled triaxial tests was conducted on Nanyang expansive clay to investigate the effects of dry density and suction on dilatancy and strength.The suction of the soil samples was controlled using a vapour equilibrium technique,with four suction levels ranging from 3.29 MPa to 198.14 MPa,where water retention is dominated by adsorption.The experimental results show that the tested soil exhibits a brittle failure mode under high suction,significantly distinguishing the hydro-mechanical behaviour of the soil at high suction from that observed at low suction.This brittle failure mode significantly increases the contribution of suction to peak strength compared to residual strength,causes the soil to fail before reaching the critical state,a phenomenon not observed in soils under high suction,and results in dilatancy caused by damage to the soil particle aggregates rather than particle rearrangement.The dilatancy data obtained from the triaxial tests reveal that significant soil dilatancy occurs during shear after reaching peak strength,with the maximum dilatancy angle increasing with suction and decreasing with confining pressure.However,the initial dry density has a negligible impact on the soil's dilatancy under high suction levels.This observation further supports that,for unsaturated soils under high suction levels,dilatancy is attributed to damage to soil particle aggregates rather than the rearrangement of soil particles.
基金Project(42277175)supported by the National Natural Science Foundation of ChinaProject(NRMSSHR-2022-Z08)supported by the Key Laboratory of Natural Resources Monitoring and Supervision in Southern Hilly Region,Ministry of Natural Resources,China。
文摘Narrow backfill earth pressure estimation is applied to study the stability of supporting structures in the vicinity of existing buildings.Previous narrow backfill earth pressure studies have neglected seismic-unsaturated seepage multi-field coupling,resulting in inaccurate estimates.To address these deficiencies,this paper proposed a calculation method for seismic passive earth pressure in unsaturated narrow backfill,based on inclined thin-layer units.It considers the interlayer shear stress,arching effect,and the multi-field coupling of seismic-unsaturated seepage.Additionally,this paper includes a parametric sensitivity analysis.The outcomes indicate that the earthquake passive ground pressure of unsaturated narrow backfill can be reduced by increasing the aspect ratio,seismic acceleration coefficient,and unsaturation parameterα.It can also be reduced by decreasing the effective interior friction angle,soil cohesion,wallearth friction angle,and vertical discharge.Furthermore,for any width soil,lowering the elevation of the action point of passive thrust can be attained by raising the effective interior friction angle,wall-earth friction angle,and unsaturation parameterα.Reducing soil cohesion,seismic acceleration coefficient,and vertical discharge can also lower the height of the application point of passive thrust.
基金supported by the National Natural Science Foundation of China(12362032)the Key Research and Development Program of Gansu Province-Social Development(25YFGA072)+2 种基金Natural Science Foundation of Gansu Province(22JR5RA805)Key Research and Development and Transformation Program of Qinghai Province(2025-QY-217)Gansu Province University Industry Support Plan(2025CYZC-033).
文摘The engineering diseases caused by seasonal sulfate saline soil in Hexi region of Gansu Province seriously affect the local infrastructure construction and operation maintenance.To address this issue,this study explored the thermal mass transfer law,pore fluid phase transition,soil deformation and microstructure of unsaturated sulfate saline soil under the open system.Firstly,based on the theories of porous media mechanics and continuum mechanics,combined with the conservation equations of mass,energy and momentum and considering the phase transition of pore fluid,a multi-field coupled mathematical model of hydro-thermal-salt-gasmechanical for unsaturated sulfate saline soil was established.Secondly,basic unknown variables such as pore water pressure,concentration,temperature,porosity,and displacement were selected to perform numerical simulation analysis on the equation system by“Comsol Multiphysics”finite element method.Finally,a comparative analysis was conducted between the on-site measured data and the numerical simulation results.The results show that the water and salt phase transitions caused by temperature change could lead to soil salt heave and frost heave,alter the pore structure of the soil,and reduce the compactness of the soil,ultimately being reflected in the changes in soil porosity.The influence of external temperature on soil temperature gradually decreases with increasing depth,and the sensitivity of frozen areas to external temperature is much higher than that of unfrozen areas.This study not only enriches the theoretical results of thermal mass transfer law and deformation of unsaturated sulfate saline soil,but also provides practical guidance for the prevention and control of engineering diseases in local sulfate saline soil.
基金funded by the National Natural Science Foundation of China (Grant Nos.42230712,42472357)the China Postdoctoral Science Foundation (Grant No.2023MD734211).
文摘Loess is susceptible to loading effects such as significant changes in strength and volume variation caused by loading and wetting.In this study,considering the different connection states of pore water and gas in loess fabric,the gas phase closure case is incorporated into a unified form of the generalized effective stress framework,introducing a damage parameter considering the effects of closed pore gas.The loading effects of unsaturated loess under wide variations in saturation are described in a unified way,and the model performance is verified by corresponding stress and hydraulic path tests.The results indicated that the collapse response involves the initial void ratio of loess,and the coupled outwards motion of the loading-collapse(LC)yield surface under loading enhances its structural strength.Suction-enhanced yield stress requires a greater"tensile stress"to counteract its structural stability.The nucleation of bubbles at high saturation causes a decrease in yield stress.The loading effect exhibits a smaller collapse behavior when the influence of closed gas is considered,whereas the suction path does not cross the LC in the stress space under hydraulic action for the same parameters,which amplifies the influence of closed gas on loess deformation.
基金the National Natural Science Foundation of China(Grant Nos.42172298,42002289)the Shanghai Geological Star Program for their financial support.
文摘Compaction grouting is primarily applied based on empiricism,and it is challenging to quantify its densification effect.To address this issue,five sets of laboratory model tests on ideal compaction grouting were conducted,with varying pressures from 400 kPa to 800 kPa,to quantitatively evaluate the densification effect in unsaturated soils.The response of surrounding soil during compaction grouting was monitored.The changes in dry density and void ratio induced by compaction grouting were obtained by monitoring volumetric water content to determine compaction efficiency.In addition,a model was developed and validated to predict the effective compaction range.The results show that soil dry density increased rapidly during compaction grouting before being stabilized at a consistent level.As expected,it is positively correlated with grouting pressures(GPs)and negatively correlated with the distance from the injection point.At higher GPs,the difference in densification effect around the injection point after compaction grouting was significant.Interestingly,variations in ultimate dry density and peak earth pressures perpendicular to the injection direction exhibited axisymmetric behavior around the injection point when comparing the dry density and earth pressure results.Furthermore,soil densification resulted in a decrease in suction.However,no significant effect of GP on suction at different soil positions was observed.Moreover,compaction efficiency decreased with increasing distance from the injection point,showing a strong linear relationship.In addition,the model results for the effective compaction range were basically consistent with the extrapolated values from the experimental results.
基金financially supported by NSERC,CanadaDiscovery Grant 2020(Grant No.5808).
文摘A simplified analytical approach is proposed for predicting the load-displacement behavior of single piles in unsaturated soils considering the contribution from the nonlinear shear strength and soil stiffness influenced by matric suction.This approach includes a Modified Load Transfer Model(MLTM)that can predict the nonlinear relationships between the shear stress and pile-soil relative displacement along the pile shaft,and between the pile base resistance and base settlement.The proposed model is also extended for pile groups to incorporate the interaction effects between individual piles.The analytical approach is validated through a comparative analysis with the measurements from two single pile tests and one pile group test.In addition,a finite element analysis using 3D modeling is carried out to investigate the behavior of pile groups in various unsaturated conditions.This is accomplished with a user-defined subroutine that is written and implemented in ABAQUS to simulate the nonlinear mechanical behavior of unsaturated soils.The predictions derived from the proposed analytical and numerical methods compare well with the measurements of a published experimental study.The proposed methodologies have the potential to be applied in geotechnical engineering practice for the rational design of single piles and pile groups in unsaturated soils.
基金supported by the National Natural Science Foundation of China(Nos.22201049,22471046)the Ba-Gui Youth Top-notch Talents Project of Guangxithe National HighLevel Personnel of Special Support Program for Young Top-notch Talents(9th batch)。
文摘The selective addition reaction of unsaturated C-C bonds has always been a classic and constant research topic.Different from well-developed hydroboration,hydrosilylation,and hydrostannylation reaction,hydrogermylation reaction remains challenging which hasn't been much reported.Herein,we developed a new metal-porous ligand polymers Pd1@POL-PPh_(n)Cy_(m)(n+m=3)with monoatomic dispersion characteristics for highly selective and efficient hydrogermylation of unsaturated C-C bonds,including alkynes,alkenes,and allenes.X-ray photoelectron spectroscopy and theoretical calculations further proved the introduction of cyclohexyl could gently adjust the charge on monoatomic Pd center which effectively facilitate the recognition and transformation of various substrates.With the electrically fine-tuned single atom palladium catalysts,we realized theα-germanium addition for the first time,obtaining corresponding allyl germanium and alkyl germanium compounds.
基金supported by the National Key Research and Development Program of China(No.2020YFA0607800)the National Natural Science Foundation of China(Nos.42022039 and 42130606)Beijing National Laboratory for Molecular Sciences(No.BNLMS-CXXM-202011),the Youth Innovation Promotion Association of Chinese Academy of Sciences(No.Y2021013).
文摘Unsaturated alcohols are a class of Biogenic volatile organic compounds(BVOCs)emitted in large quantities by plants when damaged or under adverse environmental conditions,and studies on their atmospheric degradation at night are still lacking.We used chamber experiments to study the gas-phase reactions of three unsaturated alcohols,E-2-penten-1-ol,Z-2-hexen-1-ol and Z-3-hepten-1-ol,with NO_(3)radicals(NO_(3)•)during the night.The rate constants of these reactions were(11.7±1.76)×10^(−13),(8.55±1.33)×10^(−13)and(6.08±0.47)×10^(−13)cm^(3)/(molecule·s)at 298K and 760 Torr,respectively.In contrast,the reaction rate of similar substances with ozone was about 10^(−18)cm^(3)/(molecule·s),which indicates that the reaction with NO_(3)•is themain oxidation pathway for unsaturated alcohols at night.Small molecule aldehydes and ketones were the main gas-phase organic products of the reaction of three aldehydes and ketones with NO_(3)•,and the total small molecule aldehydes and ketones yields can reach between 45%-60%.They mainly originate from the breakage of alkoxy radicals,and different breakage sites determine different product distributions.In addition,the SOA yields of the three unsaturated alcohols with NO_(3)•were 7.1%±1.0%,12.5%±1.9%and 30.0%±4.5%,respectively,whichweremuch higher than those of similarly structured substances with O_(3)or OH radicals(•OH).The results of high-resolution mass spectrometry shows that the main components of Secondary organic aerosol(SOA)of the three unsaturated alcohols are dimeric compounds containing several nitrate groups,which are formed through the polymerization of oxyalkyl radicals.
基金funded by the European Union's Horizon 2020 research and innovation programme under a grant agreement (Grant No.847593)partially supported by the Fundamental Research Funds for the Central Universities (Grant No.22120240029).
文摘This study presents a fully coupled thermo-hydro-mechanical (THM) constitutive model for clay rocks. The model is formulated within the elastic-viscoplasticity framework, which considers nonlinearity and softening after peak strength, anisotropy of stiffness and strength, as well as permeability variation due to damage. In addition, the mechanical properties are coupled with thermal phenomena and accumulated plastic strains. The adopted nonlocal and viscoplastic approaches enhance numerical efficiency and provide the possibility to simulate localization phenomena. The model is validated against experimental data from laboratory tests conducted on Callovo-Oxfordian (COx) claystone samples that are initially unsaturated and under suction. The tests include a thermal phase where the COx specimens are subjected to different temperature increases. A good agreement with experimental data is obtained. In addition, parametric analyses are carried out to investigate the influence of the hydraulic boundary conditions (B.C.) and post-failure behavior models on the THM behavior evolution. It is shown that different drainage conditions affect the thermally induced pore pressures that, in turn, influence the onset of softening. The constitutive model presented constitutes a promising approach for simulating the most important features of the THM behavior of clay rocks. It is a tool with a high potential for application to several relevant case studies, such as thermal fracturing analysis of nuclear waste disposal systems.
基金supported by the research project from the Ministry of Higher Education and Science of the Republic of Kazakhstan(Grant No.AP19675456)Nazarbayev University Collaborative Research Program(CRP)(Grant No.111024CRP2010)Collaborative Research Program(CRP)(Grant No.111024CRP2011).
文摘Unsaturated soil mechanics is crucial in understanding ground conditions and constructing geotechnical structures,particularly amidst the challenges posed by global climate change.Nevertheless,acquiring accurate soil suction values remains challenging due to limitations in existing methodologies,such as susceptibility to cavitation,high costs,and time-intensive procedures.Hence,this study employs a high-suction polymer sensor(HSPS)to evaluate the polymer's performance in determining soil suction.Subsequently,the polymers were used to measure unsaturated soil properties,especially soil-water characteristics curves(SWCC),based on osmotic principles.Five polymer samples classified as superabsorbent polymers(SAP)were synthesized with varying degrees of crosslinking,and their properties were assessed through swelling test and Fourier-transform infrared spectroscopy(FTIR).The soil sample from Turan,located within Nazarbayev University,was analyzed using a bimodal equation to determine the best fit.Results revealed that the swelling value and structural integrity of the polymer significantly affect soil suction capacity,with the findings being deemed temperature-independent,thereby obviating the need for calibration.Two potential factors hindering suction increase were identified:cavitation within the polymer or a reduction in the osmotic gradient due to polymer transformation into hydrogel formation.Overall,the novel polymer shows promise as an alternate material for SWCC measurement considering its simple method and being more sustainable compared to the other polymers,although further investigation is required to enhance the suction potential.
