Impact of effective stress on permeability for carbonate fractured-vuggy rocks

To gain insight into the flow mechanisms and stress sensitivity for fractured-vuggy reservoirs,several core models with different structural characteristics were designed and fabricated to investigate the impact of effective stress on permeability for carbonate fractured-vuggy rocks(CFVR).It shows that the permeability performance curves under different pore and confining pressures(i.e.altered stress conditions)for the fractured core models and the vuggy core models have similar change patterns.The ranges of permeability variation are significantly wider at high pore pressures,indicating that permeability reduction is the most significant during the early stage of development for fractured-vuggy reservoirs.Since each obtained effective stress coefficient for permeability(ESCP)varies with the changes in confining pressure and pore pressure,the effective stresses for permeability of four representative CFVR show obvious nonlinear characteristics,and the variation ranges of ESCP are all between 0 and 1.Meanwhile,a comprehensive ESCP mathematical model considering triple media,including matrix pores,fractures,and dissolved vugs,was proposed.It is proved theoretically that the ESCP of CFVR generally varies between 0 and 1.Additionally,the regression results showed that the power model ranked highest among the four empirical models mainly applied in stress sensitivity characterization,followed by the logarithmic model,exponential model,and binomial model.The concept of“permeability decline rate”was introduced to better evaluate the stress sensitivity performance for CFVR,in which the one-fracture rock is the strongest,followed by the fracture-vug rock and two-horizontalfracture rock;the through-hole rock is the weakest.In general,this study provides a theoretical basis to guide the design of development and adjustment programs for carbonate fractured-vuggy reservoirs.

Enhanced superelasticity and reversible elastocaloric effect in nano-grained NiTi alloys with low stress hysteresis

Solid-state cooling technologies have been considered as potential alternatives for vapor compression cooling systems.The search for refrigeration materials displaying a unique combination of pronounced caloric effect,low hysteresis,and high reversibility on phase transformation was very active in recent years.Here,we achieved increase in the elastocaloric reversibility and decrease in the friction dissipation of martensite transformations in the superelastic nano-grained NiTi alloys obtained by cold rolling and annealing treatment,with very low stress hysteresis(6.3 MPa)under a large applied strain(5%).Large adiabatic temperature changes(△T_(max)=16.3 K atε=5%)and moderate COP_(mater)values(maximum COP_(mater)=11.8 atε=2%)were achieved.The present nano-grained NiTi alloys exhibited great potential for applications as a highly efficient elastocaloric material.

Horizontal dynamic response of a large-diameter pipe pile considering the second-order effect of axial force

The second-order effect of axial force on horizontal vibrating characteristics of a large-diameter pipe pile is theoretically investigated.Governing equations of the pile-soil system are established based on elastodynamics.Threedimensional wave equations of soil are decoupled through differential transformation and variable separation.Consequently,expressions of soil displacements and horizontal resistances can be obtained.An analytical solution of the pile is derived based on continuity conditions between the pile and soil,subsequently from which expressions of the complex impedances are deduced.Analyses are carried out to examine the second-order effect of axial force on the horizontal vibrating behavior of the pipe pile.Some conclusions can be summarized as follows： stiffness and damping factors are decreased with the application of axial force on the pile head; distributions of the pile horizontal displacement and rotation angle are regenerated due to the second-order effect of the applied axial force; and redistributions of the bending moment and shearing force occur due to the second-order effect of the applied axial force.

An 8-Connected Chiral Lanthanide Metal-organic Framework Constructed from Naturally Camphoric Acid:Crystal Structure,Vibrational Circular Dichroism Spectroscopy and Second-order Nonlinear Optical Effect

A chiral lanthanide metal-organic framework based on enantiopure camphoric acid （D-H2cam）, [Nd3（D-cam）8（H2O）4Cl]n （1）, has been synthesized and characterized by single-crystal X-ray structural analysis, elemental analysis, IR, thermal gravimetric, and X-ray powder diffraction. Crystal data for the title compound are as follows： orthorhombic system, space group P212121 with a = 13.8287（7）, b = 14.0715（7）, c = 25.7403（12） A^°, V = 5008.8（4） A^°3, Mr = 1333.08, Z = 4, F（000） = 2644, Dc = 1.768 g/cm^3, μ（MoKα） = 3.189 mm^-1, the final R = 0.0351 and wR = 0.0814 （I 〉 2σ（I））. Compound 1 displays an 8-connected bcu topology 3D framework and hydrogen-bonding interactions stabilize the solid-state structure. The vibrational circular dichroism （VCD） spectrum and second-order nonlinear optical effect of compound 1 have been studied in the solid state.

Clinical effects of nonconvulsive electrotherapy combined with mindfulness-based stress reduction and changes of serum inflammatory factors in depression

BACKGROUND Depression is a common and serious psychological condition,which seriously affects individual well-being and functional ability.Traditional treatment methods include drug therapy and psychological counseling;however,these methods have different degrees of side effects and limitations.In recent years,nonconvulsive electrotherapy(NET)has attracted increasing attention as a noninvasive treatment method.However,the clinical efficacy and potential mechanism of NET on depression are still unclear.We hypothesized that NET has a positive clinical effect in the treatment of depression,and may have a regulatory effect on serum inflammatory factors during treatment.AIM To assess the effects of NET on depression and analyze changes in serum inflammatory factors.METHODS This retrospective study enrolled 140 patients undergoing treatment for depression between May 2017 and June 2022,the observation group that received a combination of mindfulness-based stress reduction(MBSR)and NET treatment(n=70)and the control group that only received MBSR therapy(n=70).The clinical effectiveness of the treatment was evaluated by assessing various factors,including the Hamilton Depression Scale(HAMD)-17,self-rating idea of suicide scale(SSIOS),Pittsburgh Sleep Quality Index(PSQI),and levels of serum inflammatory factors before and after 8 wk of treatment.The quality of life scores between the two groups were compared.Comparisons were made using t and χ^(2) tests.RESULTS After 8 wk of treatment,the observation group exhibited a 91.43%overall effectiveness rate which was higher than that of the control group which was 74.29%(64 vs 52,χ^(2)=7.241;P<0.05).The HAMD,SSIOS,and PSQI scores showed a significant decrease in both groups.Moreover,the observation group had lower scores than the control group(10.37±2.04 vs 14.02±2.16,t=10.280;1.67±0.28 vs 0.87±0.12,t=21.970;5.29±1.33 vs 7.94±1.35,t=11.700;P both<0.001).Additionally,there was a notable decrease in the IL-2,IL-1β,and IL-6 in both groups after treatment.Furthermore,the observation group exhibited superior serum inflammatory factors compared to the control group(70.12±10.32 vs 102.24±20.21,t=11.840;19.35±2.46 vs 22.27±2.13,t=7.508;32.25±4.6 vs 39.42±4.23,t=9.565;P both<0.001).Moreover,the observation group exhibited significantly improved quality of life scores compared to the control group(Social function:19.25±2.76 vs 16.23±2.34;Emotions:18.54±2.83 vs 12.28±2.16;Environment:18.49±2.48 vs 16.56±3.44;Physical health:19.53±2.39 vs 16.62±3.46;P both<0.001)after treatment.CONCLUSION MBSR combined with NET effectively alleviates depression,lowers inflammation(IL-2,IL-1β,and IL-6),reduces suicidal thoughts,enhances sleep,and improves the quality of life of individuals with depression.

The Moderating Effect of Organizational Identification on Occupational Stress and Insomnia Among Nurses

Objective:To explore the relationship between organizational identification,occupational stress,and insomnia among nurses and to analyze the moderating role of organizational identification between occupational stress and insomnia.Methods:Through stratified sampling,720 nurses working in a tertiary A-level hospital in Shandong Province from March to May 2021 were surveyed using an effort-reward imbalance questionnaire,an organizational identification questionnaire,and the Athens Insomnia scale.Results:Organizational identification was negatively correlated with occupational stress and insomnia(r_(1)=-0.121,P_(1)<0.01;r_(2)=-0.144,P_(2)<0.01).Occupational stress was positively correlated with insomnia(r=0.379,P<0.01).Organizational identity significantly moderated nurses’occupational stress and insomnia(β=-0.192,t=-2.558,P<0.05).Conclusion:Occupational stress and organizational identification can predict insomnia.Organizational identification could negatively mediate the relationship between occupational stress and insomnia.Improving organizational identification may help alleviate insomnia symptoms by relieving occupational stress.

Derivation of a second-order model for Reynolds stress using renormalization group analysis and the two-scale expansion technique

With the two-scale expansion technique proposed by Yoshizawa,the turbulent fluctuating field is expanded around the isotropic field.At a low-order two-scale expansion,applying the mode coupling approximation in the Yakhot-Orszag renormalization group method to analyze the fluctuating field,the Reynolds-average terms in the Reynolds stress transport equation,such as the convective term,the pressure-gradient-velocity correlation term and the dissipation term,are modeled.Two numerical examples：turbulent flow past a backward-facing step and the fully developed flow in a rotating channel,are presented for testing the efficiency of the proposed second-order model.For these two numerical examples,the proposed model performs as well as the Gibson-Launder （GL） model,giving better prediction than the standard k-ε model,especially in the abilities to calculate the secondary flow in the backward-facing step flow and to capture the asymmetric turbulent structure caused by frame rotation.

Dynamic Analysis of Kineto-Elastic Beam System with Second-order Effect

Dynamic equations of motional flexible beam elements were derived considering second-order effect. Non-linear finite element method and three-node Euler-Bernoulli beam elements were used. Because accuracy is higher in non-linear structural analysis,three-node beam elements are used to deduce shape functions and stiffness matrices in dynamic equations of flexible elements. Static condensation method was used to obtain the finial dynamic equations of three-node beam elements. According to geometrical relations of nodal displacements in concomitant and global coordinate system,dynamic equations of elements can be transformed to global coordinate system by concomitant coordinate method in order to build the global dynamic equations. Analyzed amplitude condition of flexible arm support of a port crane,the results show that second-order effect should be considered in kinetic-elastic analysis for heavy load machinery of big flexibility.

Effect of stress on microstructures of creep-aged 2524 alloy

Microstructures of creep-aged 2524 （A1-4.3Cu-1.5Mg） aged at 170 ℃ with various stresses （0, 173 and 250 MPa） were studied on a creep machine. Ageing hardness curves under various stresses were plotted and the corresponding microstructures were characterized by transmission electron microscopy （TEM）. The results show that the value of peak hardness is increased, while the time to reach the peak hardness is reduced under an external stress. Meanwhile, the length of S（Al2CuMg） phase is shorter and the number density of S phases is larger in the creep-aged alloy. The predominant contribution to the peak hardness can be ascribed to the GPB zones with an elastic stress.

Effects of Drought Stress on Germination of Tall Fescue

[Objective] The aim was to explore the effects of drought stress on germination of tall fescue.[Method] Simulation drought experiment on 14 varieties of tall fescue seeds by PEG-6000 researched its germination effect under drought resistance.[Result] The relative germination rate of all tall fescue varieties declined with intensifying drought stress level with the water potential of-0.6 Mpa as the turning point;the relative germination rate of tall fescue existed linear relationship with drought stress：Y = 70.412X ＋ 103.11,r=0.988 8.The sensible water potential range was ≥-0.40 Mpa for tall fescue under drought stress.LC50 of water potential was-0.76 Mpa,the lethal water potential was-1.33 Mpa.Arid Ⅲ,Crossfire Ⅱ and Traple A had stronger drought resistant ability,but Pixie,Infero and Poppoint had weaker drought resistant ability.[Conclusion] This study had provided reference for cultivated pasture and drought resistant breeding.

Effect of Exogenous Sodium Hydrosulfide Mitigating Salt Stress on Chestnut (Castanea mollissima) Seedlings

This study was conducted to investigate the alleviating effect of exogenous hydrogen sulfide on chestnut seedlings under salt stress. The effects of different concentrations of （0, 0.1, 0.2, 0.5, 1.0 and 2.0 mmol/L） sodium hydrosulfide （NariS） on the photosynthesis of ＇Hongli 2＇ chestnut seedlings and the chlorophyll content, proline content and malondialdehyde （MDA） content in chestnut leaves under 100 mM NaCI stress were investigated. According to the results, spraying exogenous NariS had positive effects on photosynthesis of chestnut leaves. The application of NariS could alleviate the damage caused by salt stress on the leaves of chestnut seedlings to different degrees. Compared with the sole treatment with 100 mmol/L NaCI, the chlorophyll content and the proline content were improved. Moreover, MDA content had a significant drop, which effectively reduced the damage of cell membrane under salt stress, The alleviating effect was not obvious with the in- crease of treatment concentration, and the 0.5 and 1.0 mmol/L NariS treatments exhibited better effects.

Effect of Different Kinds of Growth-promoting Rhizobacteria on Physiological and Biochemical Characteristics of Medicago sative Linn. Seedlings under the Stress of Na_2CO_3

[Objective] The study aimed to explore the influences of Plant growth-promoting rhizobacteria（PGPR）on salt tolerance and physiological effect of seedlings of Medicago sative L.[Method] Three different kinds of growth-promoting rhizobacteria solutions were used to spray on M.sative seedlings and the influences of different kinds of growth-promoting rhizobacteria on physiological and biochemical characteristics of M.sative seedlings under 75 mmol/L of Na2CO3 were studied.[Results] Compared with the control group,the chlorophyll,free proline,soluble sugar and soluble protein content of M.sative seedlings treated with different kinds of growth-promoting rhizobacteria were increased,while the effect of CS3 treatment was the best.[Conclusion] The growth-promoting rhizobacteria could promote growth and development of M.sative as well as increased its resistance.

Effects of Water Stress on Some Physiological Characteristics and Yield Compensation of Rice in Booting Stage

[Objective] The physiological characteristics and yield compensation effects of rice in booting stage were studied after water recovery when rice suffered water stress to provide references for improving rice water utilization efficiency and its drought resistance. [Method] The pot experiments with five rice varieties under three different treatments of water stresses were conducted to study physical signs every six days after water water-recovery. [Result] Along with the increase of water recov- ery, leaf water potential, SPAD and Pn values in treatment B （light drought） in- creased fast, and its compensation effect of the soluble sugar content was higher than that of treatment C （severe drought）; all sap flow speeds in treatments with water stresses fell. As for yield components, panicles per plant and spikelets per panicle decreased with water stress degree, and the decline of spikelets per pani- cle, in particular, was greatly influenced by water stress. Seed setting percentages in treatment B most reached peaks of different varieties, except of D you No. 363. The thousand-seed weight and ear weight per plant in treatment B and C both dropped, compared with control group. [Conclusion] When regular management was resumed after rice underwent water stress at booting stage, many characteristics and yield traits of rice got favorable compensation effects in the light water-stress treatments.

Time-sensitivity of the Kaiser effect of acoustic emission in limestone and its application to measurements of in-situ stress

Measuring in-situ stress by using the Kaiser effect in rocks has such advantages as timeefficiency, low cost and little limitation, but the precision of the method is dependent on rock properties and delay time of the measurement. In this paper, experiments on the Kaiser effect in limestones were performed, and it was found that the limestones had good ability to retain a memory of their recent stress history and high time-sensitivity. The longer the experiment was delayed from the extraction of the stone, the larger the Felicity ratio was. As the Felicity ratio approached l, significant Kaiser effect was observed. In-situ stress should be determined by the limestone measurements when the delay time was 40-120 days. Finally, the in-situ stress in a limestone formation could be successfully measured in practice.

Alleviation Effect of Lanthanum on Cadmium Stress in Seedling Hydroponic Culture of Kidney Bean and Corn

The seedling hydroponic culture experiment of kidney bean （ Phaseolus vulgaris ） and corn （ Zea mays ） was conducted to investigate the alleviation effect of lanthanum on Cd stress. It is found that growth is seriously inhibited and metabolism is maladjusted in the two crops under 30 and 300 μmol·L^-1 Cd^2＋ stress. Plant height, taproot length, leaf area, and fresh or dry weight of root, stem, and leaf are all obviously decreased. Further, chlorophyll content decreases, membrane permeability, malonydialdehyde （MDA） content, activities of catalase （CAT） and peroxidase （POD） increases under Cd stress, as compared with the control. The damage to these two crops becomes more conspicuous with the prolongation of Cd stress. It is suggested that lanthanum might help kidney bean and corn seedlings alleviate Cd stress by improving the photosynthetic capacity, reducing membrane permeability and MDA content, and maintaining the activities of CAT and POD of these two crops.

Strain-rate effect on initial crush stress of irregular honeycomb under dynamic loading and its deformation mechanism

The seemingly contradictory understandings of the initial crush stress of cellular materials under dynamic loadings exist in the literature, and a comprehensive analysis of this issue is carried out with using direct information of local stress and strain. Local stress/strain calculation methods are applied to determine the initial crush stresses and the strain rates at initial crush from a cell-based finite element model of irregular honeycomb under dynamic loadings. The initial crush stress under constant-velocity compression is identical to the quasi-static one, but less than the one under direct impact, i.e. the initial crush stresses under different dynamic loadings could be very different even though there is no strain-rate effect of matrix material. A power-law relation between the initial crush stress and the strain rate is explored to describe the strain-rate effect on the initial crush stress of irregular honeycomb when the local strain rate exceeds a critical value, below which there is no strain-rate effect of irregular honeycomb. Deformation mechanisms of the initial crush behavior under dynamic loadings are also explored.The deformation modes of the initial crush region in the front of plastic compaction wave are different under different dynamic loadings.

Effect of surface stress and surface-induced stress on behavior of piezoelectric nanobeam

A new continuum model is developed to study the influence of surface stress on the behaviors of piezoelectric nanobeams. Different from existing piezoelectric surface models which only consider the surface properties, the proposed model takes surfaceinduced initial fields into consideration. Due to the fact that the surface-induced initial fields are totally different under various boundary conditions, two kinds of beams, the doubly-clamped beam and the cantilever beam, are analyzed. Furthermore, boundary conditions can affect not only the initial state of the piezoelectric nanobeam but also the forms of the governing equations. Based on the Euler-Bernoulli beam theory, the nonlin- ear Green-Lagrangian strain-displacement relationship is applied. In addition, the surface area change is also considered in the proposed model. The governing equations of the doubly-clamped and cantilever beams are derived by the energy variation principle. Com- pared with existing Young-Laplace models, the proposed model for the doubly-clamped beam is similar to the Young-Laplace models. However~ the governing equation of the cantilever beam derived by the proposed model is very different from that derived by the Young-Laplace models. The behaviors of piezoelectric nanobeams predicted by these two models Mso have significant discrepancies, which is owing to the surface-induced initial fields in the bulk beam.

Size effects on flow stress of C3602 in cylinder compression with different lubricants

Micro parts are more difficult to be formed than macro parts because of size effects. The size effects on the flow stress of copper alloy C3602 with different lubricants were studied. Specimens were heat treated at 350℃ for 1 h and 700℃ for 3 h in nitrogen atmosphere, respectively. The initial diameters of the specimens were varied from 5 to 1 mm with a height-to-diameter ratio h0/D0 = 1.5. Cylinder compression was carried out in the lubrication condition with talc powder, without lubricant, with petroleum jelly, and with vegetable oil. The experiment was carried out at room temperature on a universal testing machine INSTRON 5569 with a strain rate of ε = 0.0025 A. The results show that with the same lubricant, the yield strength decreases with a decrease in specimen size for the specimens annealed at 350℃ for 1 b; however, it increases with a decrease in specimen size for the specimens annealed at 700℃ for 3 h. The yield strength decreases with an increase in grain size. The influences of lubricants on yield strength become larger with miniaturization of the specimens.

EFFECTIVE STRESS LAWS FOR MULTI_POROSITY MEDIA

In this paper, the effective stress for multi-porosity elasticity model is presented by means of stress analysis for double porosity media elements. It is found that the effective stress law is not unique, it depends on the hypothesis of constitutive equations for multi-porosity media. Diversified effective stress laws for multi-porosity are developed.

Torsional dynamic response of tapered pile considering compaction effect and stress diffusion effect

Considering both the compaction effect of pile surrounding soil and the stress diffusion effect of pile end soil,this paper theoretically investigates the torsional vibration characteristics of tapered pile.Utilizing the complex stiffness transfer model to simulate compaction effect and tapered fictitious soil pile model to simulate stress diffusion,the analytical solution for the torsional impedance at tapered pile top is obtained by virtue of Laplace transform technique and impedance transfer method.Based on the present solution,a parametric study is conducted to investigate the rationality of the present solution and the influence of soil and pile properties on the torsional vibration characteristics of tapered pile embedded in layered soil.The results show that,both the compaction effect and stress diffusion effect have significant influence on the torsional vibration characteristics of tapered pile,and these two factors should be considered during the dynamic design of pile foundation.