To reveal the rock burst mechanism,the stress and failure characteristics of coal-rock strata under different advancing speeds of mining working face were explored by theoretical analysis,simulation,and engineering mo...To reveal the rock burst mechanism,the stress and failure characteristics of coal-rock strata under different advancing speeds of mining working face were explored by theoretical analysis,simulation,and engineering monitoring.The relationship between energy accumulation and release was analyzed,and a reasonable mining speed according to specific projects was recommended.The theoretical analysis shows that as the mining speed increases from 4 to 15 m/d,the rheological coefficient of coal mass ranges from 0.9 to 0.4,and the elastic energy of coal mass accumulation varies from 100 to 900 kJ.Based on the simulation,there is a critical advancing speed,the iteration numbers of simulation are less than 15,000 per mining 10 m coal seam,the overburden structure is obvious,the abutment pressure in coal mass is large,and the accumulated energy is large,which is easy to cause strong rock burst.When the iteration number is greater than 15,000,the static force of coal mass increases slightly,but there is no obvious rock burst.Based on engineering monitoring,the mining speed of a mine is less than 8 m/d,and the periodic weighting distance is about 17 m;as the mining speed is greater than 10 m/d,and the periodic weighting distance is greater than 20 m;as the mining speed is 3-8 m/d,and the range of high stress in surrounding rock is 48 m;as the advancing speed is 8-12 m/d,and the high-stress range in surrounding rock is 80 m.Moreover,as the mining speed is less than 8 cut cycles,the micro seismic energy is less than 10,000 J;as the mining speed is 12 cut cycles,the microseismic energy is about 20,000 J.In summary,the advancing speed is positively correlated with the micro seismic event;as the mining speed increases,the accumulated elastic energy of surrounding rock is greater,which is easy to cause rock burst.The comprehensive analysis indicates the daily advance speed of the mine is not more than 12 cut cycles.展开更多
Precipitation strengthening is a pivotal mechanism for enhancing the mechanical properties of low-density alloys.A detailed analysis of microstructural evolution during thermal processing is imperative to thoroughly u...Precipitation strengthening is a pivotal mechanism for enhancing the mechanical properties of low-density alloys.A detailed analysis of microstructural evolution during thermal processing is imperative to thoroughly understand its strengthening behavior.This study employed the Bähr D805L quenching dilatometer system to study the formation,evolution,and impact on the contribution of nano-precipitates on the mechanical behavior of Fe-21Mn-10Al-5Ni-C(nominal composition)low-density alloy during continuous cooling.The study unveiled the precipitation mechanism of nano-particles within the austenite(γ)matrix at cooling rates in the range of 40-0.1℃·s^(-1).Moreover,the addition of Ni in Fe-21Mn-10Al-5Ni-C low-density alloy enhances the atomic size factor,promoting alloy spinodal decomposition and ordering.During slow cooling,B2 phases precipitate along grain boundaries,accompanied by the formation of a precipitation-free zone(PFZ)near the boundaries and the dissolution of some later nucleated small particles.These phenomena are a primary mechanism that suppresses the precipitation of B2 phases within theγmatrix.展开更多
Polymerization-induced self-assembly(PISA)has become one of the most versatile approaches for scalable preparation of linear block copolymer nanoparticles with various morphologies.However,the controlled introduction ...Polymerization-induced self-assembly(PISA)has become one of the most versatile approaches for scalable preparation of linear block copolymer nanoparticles with various morphologies.However,the controlled introduction of branching into the core-forming block and the effect on the morphologies of block copolymer nanoparticles under PISA conditions have rarely been explored.Herein,a series of multifunctional macromolecular chain transfer agents(macro-CTAs)were first synthesized by a two-step green light-activated photoiniferter polymerization using two types of chain transfer monomers(CTMs).These macro-CTAs were then used to mediate reversible addition-fragmentation chain transfer(RAFT)dispersion polymerization of styrene(St)to prepare block copolymers with different core-forming block structures and the assemblies.The effect of the core-forming block structure on the morphology of block copolymer nanoparticles was investigated in detail.Transmission electron microscopy(TEM)analysis indicated that the brush-like core-forming block structure facilitated the formation of higher-order morphologies,while the branched core-forming block structure favored the formation of lower-order morphologies.Moreover,it was found that using macroCTAs with a shorter length also promoted the formation of higher-order morphologies.Finally,structures of block copolymers and the assemblies were further controlled by changing the structure of macro-CTA or using a binary mixture of two different macro-CTAs.We expect that this work not only sheds light on the synthesis of block copolymer nanoparticles but also provide important mechanistic insights into PISA of nonlinear block copolymers.展开更多
This paper focuses on the relationship between the microstructure and tensile properties of Fe-Mn-Al-C low-density high-strength steel processes by hot-rolling and air-cooling process. The microstructure analysis reve...This paper focuses on the relationship between the microstructure and tensile properties of Fe-Mn-Al-C low-density high-strength steel processes by hot-rolling and air-cooling process. The microstructure analysis reveals that the combination of hot-rolling and air-cooling results in the formation of heterogeneous structures comprising different-sized γ and B_(2) phases in the low-density steel with the addition of nickel (Ni). The addition of Ni promotes the formation of the B_(2) phase and induces the pinning of B_(2) phase particles at the γ grain boundaries. This pinning effect effectively hinders the growth of the γ grains, leading to grain refinement. The tensile test results demonstrate that LDS-5Ni (low-density steel, LDS) exhibits excellent high strength and ductility combination, e.g., a tensile strength of 1535 MPa, yield strength of 1482 MPa, and elongation of 23.3%. These remarkable mechanical properties are primarily attributed to the combined strengthening contributions of grain refinement and duplex nano-sized second-phase precipitation hardening.展开更多
BACKGROUND Cervical intraepithelial neoplasia(CIN)is an important precursor of cervical cancer.Early detection and treatment can reduce the incidence of cervical cancer.AIM To investigate the detection rate of human p...BACKGROUND Cervical intraepithelial neoplasia(CIN)is an important precursor of cervical cancer.Early detection and treatment can reduce the incidence of cervical cancer.AIM To investigate the detection rate of human papillomavirus(HPV)E6/E7 mRNA in cervical tissue of patients with different types of epithelial cell neoplasia(CIN)and its relationship with CIN progression and diagnosis.METHODS One hundred women with HPV infection detected by cervical exfoliation cytology between January 2022 and January 2023 were retrospectively selected.These patients were graded CIN based on colposcopy and cervical pathology.The positive expression rates of HPV E6/E7 mRNA and HPV[polymerase chain reaction(PCR)-reverse dot crossing]were compared among all groups.Patients with HPV E6/E7 mRNA expression in the grade 1 CIN group were followed up for 1 yr.The relationship between atypical squamous epithelium and high malignant epithelial neoplasia was investigated by univariate and multivariate analysis.RESULTS The diagnostic sensitivity,specificity,and sensitivity of PCR-reverse point hybrid ization technology for secondary CIN were 70.41%,70.66%,and 0.714,respectively.Sensitivity and specificity for secondary CIN were 752%and 7853%,respectively,the area under the curve value was 0.789.Logistic Multifactorial model analysis revealed that the HPV positive rates and the HPV E6/E7 mRNA positive rates were independent risk factors of CIN grade I(P<0.05).In CIN grade I patients with positive for HPV E6/E7 mRNA,in its orientation to grade CIN patients,in its orientation to grade CIN patients,at 69.2%,compared with patients negative for HPV E6/E7 mRNA(30.8%),significant difference(P<0.05).CONCLUSION HPV E6/E7 mRNA and HPV(PCR-reverse dot hybrid)positive expression have a close relationship with CINgrade disease progression and is an independent risk factor for high-grade CIN lesions.展开更多
Perforation is a pivotal technique employed to establish main flow channels within the reservoir formation at the outset of hydraulic fracturing operations.Optimizing perforation designs is critical for augmenting the...Perforation is a pivotal technique employed to establish main flow channels within the reservoir formation at the outset of hydraulic fracturing operations.Optimizing perforation designs is critical for augmenting the efficacy of hydraulic fracturing and boosting oil or gas production.In this study,we employ a hybrid finite-discrete element method,known as the continuous–discontinuous element method(CDEM),to simulate the initiation of post-perforation hydraulic fractures and to derive enhanced design parameters.The model incorporates the four most prevalent perforation geometries,as delineated in an engineering technical report.Real-world perforations deviate from the ideal cylindrical shape,exhibiting variable cross-sectional profiles that typically manifest as an initial constriction followed by an expansion,a feature consistent across all four perforation types.Our simulations take into account variations in perforation hole geometries,cross-sectional diameters,and perforation lengths.The findings show that perforations generated by the 39g DP3 HMX perforating bullet yield the lowest breakdown pressure,which inversely correlates with increases in sectional diameter and perforation length.Moreover,this study reveals the relationship between breakdown pressure and fracture degree,providing valuable insights for engineers and designers to refine perforation strategies.展开更多
Objective Both sequential embryo transfer(SeET)and double-blastocyst transfer(DBT)can serve as embryo transfer strategies for women with recurrent implantation failure(RIF).This study aims to compare the effects of Se...Objective Both sequential embryo transfer(SeET)and double-blastocyst transfer(DBT)can serve as embryo transfer strategies for women with recurrent implantation failure(RIF).This study aims to compare the effects of SeET and DBT on pregnancy outcomes.Methods Totally,261 frozen-thawed embryo transfer cycles of 243 RIF women were included in this multicenter retrospective analysis.According to different embryo quality and transfer strategies,they were divided into four groups:group A,good-quality SeET(GQ-SeET,n=38 cycles);group B,poor-quality or mixed-quality SeET(PQ/MQ-SeET,n=31 cycles);group C,good-quality DBT(GQ-DBT,n=121 cycles);and group D,poor-quality or mixed-quality DBT(PQ/MQ-DBT,n=71 cycles).The main outcome,clinical pregnancy rate,was compared,and the generalized estimating equation(GEE)model was used to correct potential confounders that might impact pregnancy outcomes.Results GQ-DBT achieved a significantly higher clinical pregnancy rate(aOR 2.588,95%CI 1.267–5.284,P=0.009)and live birth rate(aOR 3.082,95%CI 1.482–6.412,P=0.003)than PQ/MQ-DBT.Similarly,the clinical pregnancy rate was significantly higher in GQ-SeET than in PQ/MQ-SeET(aOR 4.047,95%CI 1.218–13.450,P=0.023).The pregnancy outcomes of GQ-SeET were not significantly different from those of GQ-DBT,and the same results were found between PQ/MQ-SeET and PQ/MQ-DBT.Conclusion SeET relative to DBT did not seem to improve pregnancy outcomes for RIF patients if the embryo quality was comparable between the two groups.Better clinical pregnancy outcomes could be obtained by transferring good-quality embryos,no matter whether in SeET or DBT.Embryo quality plays a more important role in pregnancy outcomes for RIF patients.展开更多
Objective:To explore the clinical efficacy and incidence of hypoglycemia in the treatment of elderly diabetes with glimepiride combined with insulin.Methods:A total of 100 patients diagnosed with diabetes in Qinghai R...Objective:To explore the clinical efficacy and incidence of hypoglycemia in the treatment of elderly diabetes with glimepiride combined with insulin.Methods:A total of 100 patients diagnosed with diabetes in Qinghai Red Cross Hospital from January 2018 to January 2019 were selected and divided into an observation group and a control group according to the order of their visits,with 50 patients in each group.The observation group was treated with glimepiride combined with insulin,while the control group was treated with insulin alone.The blood sugar indicators,including glycated hemoglobin(HbA1c),fasting blood glucose(FBG),and 2-hour postprandial blood glucose(2h PBG),were compared between the two groups.Additionally,the incidence of hypoglycemia was compared,and the causes of hypoglycemia were analyzed and summarized,proposing corresponding countermeasures.Results:The glycated hemoglobin value of the observation group was lower than that of the control group,and the statistical analysis showed a significant difference(t=3.54,P<0.05).The fasting blood glucose value in the observation group was lower than that in the control group,with statistically significant differences(t=4.08,P<0.05).The 2-hour postprandial blood glucose value in the observation group was also lower than that in the control group,with a significant difference(t=3.82,P<0.05).The incidence of hypoglycemia in the observation group was 10%,while it was 56%in the control group,with a statistically significant difference between the two groups(χ^(2)=5.813,P<0.05).Conclusion:The efficacy of glimepiride combined with insulin in the treatment of elderly diabetes is significantly higher than that of insulin alone,with a lower incidence of hypoglycemia.展开更多
Continuum-based discrete element method(CDEM)is an explicit numerical method used for simulation of progressive failure of geological body.To improve the efficiency of contact detection and simplify the calculation st...Continuum-based discrete element method(CDEM)is an explicit numerical method used for simulation of progressive failure of geological body.To improve the efficiency of contact detection and simplify the calculation steps for contact forces,semi-spring and semi-edge are introduced in calculation.Semispring is derived from block vertex,and formed by indenting the block vertex into each face(24semisprings for a hexahedral element).The formation process of semi-edge is the same as that of semi-spring(24semi-edges for a hexahedral element).Based on the semi-springs and semi-edges,a new type of combined contact model is presented.According to this model,six contact types could be reduced to two,i.e.the semi-spring target face contact and semi-edge target edge contact.By the combined model,the contact force could be calculated directly(the information of contact type is not necessary),and the failure judgment could be executed in a straightforward way(each semi-spring and semi-edge own their characteristic areas).The algorithm has been successfully programmed in C++program.Some simple numerical cases are presented to show the validity and accuracy of this model.Finally,the failure mode,sliding distance and critical friction angle of Jiweishan landslide are studied with the combined model.展开更多
One of the main issues in environmental hydraulics is pollutant release from sediments.For instance,the strong affinity between phosphorus and sediment permits most of the phosphorus to be adsorbed on the surface of t...One of the main issues in environmental hydraulics is pollutant release from sediments.For instance,the strong affinity between phosphorus and sediment permits most of the phosphorus to be adsorbed on the surface of the sediment particles in rivers or lakes.Post sediment resuspension,phosphorus is desorbed from the sediment to the overlying water.The release of phosphorus from the resuspended sediment is an important process in the secondary pollution of water.Herein,a coupled mechanical model of the overlying water,sediment,and pollutant was established based on the experimentally gathered data.Two types of sediment with different adsorption and desorption characteristics were selected to simulate the process of sediment resuspension and phosphorus release under different hydrodynamic conditions.The simulation results were subsequently used to analyze the relationship between the flow field characteristics and phosphorus concentration,from which the relationships between velocity,particle volume fraction,turbulent kinetic energy,total phosphorus concentration,desorbed phosphorus concentration,and time were elucidated.Based on the results,phosphorus is rapidly released into the overlying water from the resuspended sediment,and it reaches a peak value in a short duration.Unlike the release process of non-adsorption pollutants,hydrodynamic conditions and sediment properties play a crucial role in the phosphorus release process.The turbulent kinetic energy rapidly increases with the flow velocity,whereas the desorbed phosphorus concentration exhibits a certain relationship with the particle volume fraction and turbulent kinetic energy.In particular,the turbulent kinetic energy increases the desorbed phosphorus concentration per unit time.Additionally,the time taken by the total phosphorus concentration to attain its peak value is closely related to the characteristics of the flow field,whereas the amount of phosphorus is closely related to sediment properties.Post sediment resuspension,the release of phosphorus shows the characteristics of a centralized and massive release,which suggests that the total phosphorus concentration in the overlying water would change in a short duration and cause secondary pollution in the water environment.展开更多
基金supported by the National Natural Science Foundation of China(52174109)Program for Innovative Research Team(in Science and Technology)in University of Henan Province(22IRTSTHN005)+1 种基金Key Research and Development Project of Henan Province(242102240029)Key Research Project of Institutions of Higher Education in Henan Province(24A580001).
文摘To reveal the rock burst mechanism,the stress and failure characteristics of coal-rock strata under different advancing speeds of mining working face were explored by theoretical analysis,simulation,and engineering monitoring.The relationship between energy accumulation and release was analyzed,and a reasonable mining speed according to specific projects was recommended.The theoretical analysis shows that as the mining speed increases from 4 to 15 m/d,the rheological coefficient of coal mass ranges from 0.9 to 0.4,and the elastic energy of coal mass accumulation varies from 100 to 900 kJ.Based on the simulation,there is a critical advancing speed,the iteration numbers of simulation are less than 15,000 per mining 10 m coal seam,the overburden structure is obvious,the abutment pressure in coal mass is large,and the accumulated energy is large,which is easy to cause strong rock burst.When the iteration number is greater than 15,000,the static force of coal mass increases slightly,but there is no obvious rock burst.Based on engineering monitoring,the mining speed of a mine is less than 8 m/d,and the periodic weighting distance is about 17 m;as the mining speed is greater than 10 m/d,and the periodic weighting distance is greater than 20 m;as the mining speed is 3-8 m/d,and the range of high stress in surrounding rock is 48 m;as the advancing speed is 8-12 m/d,and the high-stress range in surrounding rock is 80 m.Moreover,as the mining speed is less than 8 cut cycles,the micro seismic energy is less than 10,000 J;as the mining speed is 12 cut cycles,the microseismic energy is about 20,000 J.In summary,the advancing speed is positively correlated with the micro seismic event;as the mining speed increases,the accumulated elastic energy of surrounding rock is greater,which is easy to cause rock burst.The comprehensive analysis indicates the daily advance speed of the mine is not more than 12 cut cycles.
基金supported by the CNPC Scientific Research and Technology Development Project(Nos.2021ZZ03,2023ZZ11,2022DQ03-02 and 2020B-4020).
文摘Precipitation strengthening is a pivotal mechanism for enhancing the mechanical properties of low-density alloys.A detailed analysis of microstructural evolution during thermal processing is imperative to thoroughly understand its strengthening behavior.This study employed the Bähr D805L quenching dilatometer system to study the formation,evolution,and impact on the contribution of nano-precipitates on the mechanical behavior of Fe-21Mn-10Al-5Ni-C(nominal composition)low-density alloy during continuous cooling.The study unveiled the precipitation mechanism of nano-particles within the austenite(γ)matrix at cooling rates in the range of 40-0.1℃·s^(-1).Moreover,the addition of Ni in Fe-21Mn-10Al-5Ni-C low-density alloy enhances the atomic size factor,promoting alloy spinodal decomposition and ordering.During slow cooling,B2 phases precipitate along grain boundaries,accompanied by the formation of a precipitation-free zone(PFZ)near the boundaries and the dissolution of some later nucleated small particles.These phenomena are a primary mechanism that suppresses the precipitation of B2 phases within theγmatrix.
基金financially supported by the National Natural Science Foundation of China(Nos.22171055 and 52222301)the Guangdong Natural Science Foundation for Distinguished Young Scholar(No.2022B1515020078)the Science and Technology Program of Guangzhou(No.2024A04J2821)。
文摘Polymerization-induced self-assembly(PISA)has become one of the most versatile approaches for scalable preparation of linear block copolymer nanoparticles with various morphologies.However,the controlled introduction of branching into the core-forming block and the effect on the morphologies of block copolymer nanoparticles under PISA conditions have rarely been explored.Herein,a series of multifunctional macromolecular chain transfer agents(macro-CTAs)were first synthesized by a two-step green light-activated photoiniferter polymerization using two types of chain transfer monomers(CTMs).These macro-CTAs were then used to mediate reversible addition-fragmentation chain transfer(RAFT)dispersion polymerization of styrene(St)to prepare block copolymers with different core-forming block structures and the assemblies.The effect of the core-forming block structure on the morphology of block copolymer nanoparticles was investigated in detail.Transmission electron microscopy(TEM)analysis indicated that the brush-like core-forming block structure facilitated the formation of higher-order morphologies,while the branched core-forming block structure favored the formation of lower-order morphologies.Moreover,it was found that using macroCTAs with a shorter length also promoted the formation of higher-order morphologies.Finally,structures of block copolymers and the assemblies were further controlled by changing the structure of macro-CTA or using a binary mixture of two different macro-CTAs.We expect that this work not only sheds light on the synthesis of block copolymer nanoparticles but also provide important mechanistic insights into PISA of nonlinear block copolymers.
基金funding from the National Key Technologies Research and Development Program of China(No.2021YFB3703500)the National Natural Science Foundation of China(No.51771014).
文摘This paper focuses on the relationship between the microstructure and tensile properties of Fe-Mn-Al-C low-density high-strength steel processes by hot-rolling and air-cooling process. The microstructure analysis reveals that the combination of hot-rolling and air-cooling results in the formation of heterogeneous structures comprising different-sized γ and B_(2) phases in the low-density steel with the addition of nickel (Ni). The addition of Ni promotes the formation of the B_(2) phase and induces the pinning of B_(2) phase particles at the γ grain boundaries. This pinning effect effectively hinders the growth of the γ grains, leading to grain refinement. The tensile test results demonstrate that LDS-5Ni (low-density steel, LDS) exhibits excellent high strength and ductility combination, e.g., a tensile strength of 1535 MPa, yield strength of 1482 MPa, and elongation of 23.3%. These remarkable mechanical properties are primarily attributed to the combined strengthening contributions of grain refinement and duplex nano-sized second-phase precipitation hardening.
基金Scientific Research Project of Hubei Provincial Health Commission,No.WJ2021M189。
文摘BACKGROUND Cervical intraepithelial neoplasia(CIN)is an important precursor of cervical cancer.Early detection and treatment can reduce the incidence of cervical cancer.AIM To investigate the detection rate of human papillomavirus(HPV)E6/E7 mRNA in cervical tissue of patients with different types of epithelial cell neoplasia(CIN)and its relationship with CIN progression and diagnosis.METHODS One hundred women with HPV infection detected by cervical exfoliation cytology between January 2022 and January 2023 were retrospectively selected.These patients were graded CIN based on colposcopy and cervical pathology.The positive expression rates of HPV E6/E7 mRNA and HPV[polymerase chain reaction(PCR)-reverse dot crossing]were compared among all groups.Patients with HPV E6/E7 mRNA expression in the grade 1 CIN group were followed up for 1 yr.The relationship between atypical squamous epithelium and high malignant epithelial neoplasia was investigated by univariate and multivariate analysis.RESULTS The diagnostic sensitivity,specificity,and sensitivity of PCR-reverse point hybrid ization technology for secondary CIN were 70.41%,70.66%,and 0.714,respectively.Sensitivity and specificity for secondary CIN were 752%and 7853%,respectively,the area under the curve value was 0.789.Logistic Multifactorial model analysis revealed that the HPV positive rates and the HPV E6/E7 mRNA positive rates were independent risk factors of CIN grade I(P<0.05).In CIN grade I patients with positive for HPV E6/E7 mRNA,in its orientation to grade CIN patients,in its orientation to grade CIN patients,at 69.2%,compared with patients negative for HPV E6/E7 mRNA(30.8%),significant difference(P<0.05).CONCLUSION HPV E6/E7 mRNA and HPV(PCR-reverse dot hybrid)positive expression have a close relationship with CINgrade disease progression and is an independent risk factor for high-grade CIN lesions.
基金support from the National Natural Science Foundation of China(Grant Nos.52178324,12102059)the China Postdoctoral Science Foundation(Grant No.2023M743604)+1 种基金the Beijing Natural Science Foundation(Grant No.3212027),the National Key R&D Program of China(Grant No.2023YFC3007203)the 2019 Foreign Experts Plan of Hebei Province.
文摘Perforation is a pivotal technique employed to establish main flow channels within the reservoir formation at the outset of hydraulic fracturing operations.Optimizing perforation designs is critical for augmenting the efficacy of hydraulic fracturing and boosting oil or gas production.In this study,we employ a hybrid finite-discrete element method,known as the continuous–discontinuous element method(CDEM),to simulate the initiation of post-perforation hydraulic fractures and to derive enhanced design parameters.The model incorporates the four most prevalent perforation geometries,as delineated in an engineering technical report.Real-world perforations deviate from the ideal cylindrical shape,exhibiting variable cross-sectional profiles that typically manifest as an initial constriction followed by an expansion,a feature consistent across all four perforation types.Our simulations take into account variations in perforation hole geometries,cross-sectional diameters,and perforation lengths.The findings show that perforations generated by the 39g DP3 HMX perforating bullet yield the lowest breakdown pressure,which inversely correlates with increases in sectional diameter and perforation length.Moreover,this study reveals the relationship between breakdown pressure and fracture degree,providing valuable insights for engineers and designers to refine perforation strategies.
文摘Objective Both sequential embryo transfer(SeET)and double-blastocyst transfer(DBT)can serve as embryo transfer strategies for women with recurrent implantation failure(RIF).This study aims to compare the effects of SeET and DBT on pregnancy outcomes.Methods Totally,261 frozen-thawed embryo transfer cycles of 243 RIF women were included in this multicenter retrospective analysis.According to different embryo quality and transfer strategies,they were divided into four groups:group A,good-quality SeET(GQ-SeET,n=38 cycles);group B,poor-quality or mixed-quality SeET(PQ/MQ-SeET,n=31 cycles);group C,good-quality DBT(GQ-DBT,n=121 cycles);and group D,poor-quality or mixed-quality DBT(PQ/MQ-DBT,n=71 cycles).The main outcome,clinical pregnancy rate,was compared,and the generalized estimating equation(GEE)model was used to correct potential confounders that might impact pregnancy outcomes.Results GQ-DBT achieved a significantly higher clinical pregnancy rate(aOR 2.588,95%CI 1.267–5.284,P=0.009)and live birth rate(aOR 3.082,95%CI 1.482–6.412,P=0.003)than PQ/MQ-DBT.Similarly,the clinical pregnancy rate was significantly higher in GQ-SeET than in PQ/MQ-SeET(aOR 4.047,95%CI 1.218–13.450,P=0.023).The pregnancy outcomes of GQ-SeET were not significantly different from those of GQ-DBT,and the same results were found between PQ/MQ-SeET and PQ/MQ-DBT.Conclusion SeET relative to DBT did not seem to improve pregnancy outcomes for RIF patients if the embryo quality was comparable between the two groups.Better clinical pregnancy outcomes could be obtained by transferring good-quality embryos,no matter whether in SeET or DBT.Embryo quality plays a more important role in pregnancy outcomes for RIF patients.
文摘Objective:To explore the clinical efficacy and incidence of hypoglycemia in the treatment of elderly diabetes with glimepiride combined with insulin.Methods:A total of 100 patients diagnosed with diabetes in Qinghai Red Cross Hospital from January 2018 to January 2019 were selected and divided into an observation group and a control group according to the order of their visits,with 50 patients in each group.The observation group was treated with glimepiride combined with insulin,while the control group was treated with insulin alone.The blood sugar indicators,including glycated hemoglobin(HbA1c),fasting blood glucose(FBG),and 2-hour postprandial blood glucose(2h PBG),were compared between the two groups.Additionally,the incidence of hypoglycemia was compared,and the causes of hypoglycemia were analyzed and summarized,proposing corresponding countermeasures.Results:The glycated hemoglobin value of the observation group was lower than that of the control group,and the statistical analysis showed a significant difference(t=3.54,P<0.05).The fasting blood glucose value in the observation group was lower than that in the control group,with statistically significant differences(t=4.08,P<0.05).The 2-hour postprandial blood glucose value in the observation group was also lower than that in the control group,with a significant difference(t=3.82,P<0.05).The incidence of hypoglycemia in the observation group was 10%,while it was 56%in the control group,with a statistically significant difference between the two groups(χ^(2)=5.813,P<0.05).Conclusion:The efficacy of glimepiride combined with insulin in the treatment of elderly diabetes is significantly higher than that of insulin alone,with a lower incidence of hypoglycemia.
基金the National Basic Research Program of the Ministry of Science and Technology of China (Grant No. 2010CB731506)the National Key Technology Research and Development Program of the Ministry of Science and Technology of China (Grant No. 2012BAK10B01)the Youth Science Fund of National Natural Science Foundation of China (Grant No. 11302230)
文摘Continuum-based discrete element method(CDEM)is an explicit numerical method used for simulation of progressive failure of geological body.To improve the efficiency of contact detection and simplify the calculation steps for contact forces,semi-spring and semi-edge are introduced in calculation.Semispring is derived from block vertex,and formed by indenting the block vertex into each face(24semisprings for a hexahedral element).The formation process of semi-edge is the same as that of semi-spring(24semi-edges for a hexahedral element).Based on the semi-springs and semi-edges,a new type of combined contact model is presented.According to this model,six contact types could be reduced to two,i.e.the semi-spring target face contact and semi-edge target edge contact.By the combined model,the contact force could be calculated directly(the information of contact type is not necessary),and the failure judgment could be executed in a straightforward way(each semi-spring and semi-edge own their characteristic areas).The algorithm has been successfully programmed in C++program.Some simple numerical cases are presented to show the validity and accuracy of this model.Finally,the failure mode,sliding distance and critical friction angle of Jiweishan landslide are studied with the combined model.
基金This work was financially supported by the Strategic Priority Research Program of the National Key R&D Program of China(Grants 2018YFC1505500 and 2018YFC1505504)the Chinese Academy of Science(Grant XDB10030303)and the National Natural Science Foundation of China(NSFC)(Grants 11802313 and 11872117).
文摘One of the main issues in environmental hydraulics is pollutant release from sediments.For instance,the strong affinity between phosphorus and sediment permits most of the phosphorus to be adsorbed on the surface of the sediment particles in rivers or lakes.Post sediment resuspension,phosphorus is desorbed from the sediment to the overlying water.The release of phosphorus from the resuspended sediment is an important process in the secondary pollution of water.Herein,a coupled mechanical model of the overlying water,sediment,and pollutant was established based on the experimentally gathered data.Two types of sediment with different adsorption and desorption characteristics were selected to simulate the process of sediment resuspension and phosphorus release under different hydrodynamic conditions.The simulation results were subsequently used to analyze the relationship between the flow field characteristics and phosphorus concentration,from which the relationships between velocity,particle volume fraction,turbulent kinetic energy,total phosphorus concentration,desorbed phosphorus concentration,and time were elucidated.Based on the results,phosphorus is rapidly released into the overlying water from the resuspended sediment,and it reaches a peak value in a short duration.Unlike the release process of non-adsorption pollutants,hydrodynamic conditions and sediment properties play a crucial role in the phosphorus release process.The turbulent kinetic energy rapidly increases with the flow velocity,whereas the desorbed phosphorus concentration exhibits a certain relationship with the particle volume fraction and turbulent kinetic energy.In particular,the turbulent kinetic energy increases the desorbed phosphorus concentration per unit time.Additionally,the time taken by the total phosphorus concentration to attain its peak value is closely related to the characteristics of the flow field,whereas the amount of phosphorus is closely related to sediment properties.Post sediment resuspension,the release of phosphorus shows the characteristics of a centralized and massive release,which suggests that the total phosphorus concentration in the overlying water would change in a short duration and cause secondary pollution in the water environment.
