The role of metakaolin in the properties of Portland cement hydrated with ground water and sea water was described by magnetic susceptibility study. Cement pastes containing 0wt%, 10wt%, 20wt% and 30wt% replacement of...The role of metakaolin in the properties of Portland cement hydrated with ground water and sea water was described by magnetic susceptibility study. Cement pastes containing 0wt%, 10wt%, 20wt% and 30wt% replacement of metakaolin and in a water/cement （W/C） ratio of 0.4 were prepared. The susceptibility at different hydration periods was determined by Faraday Curie balance and it was related to the changes in setting time and compressive strength of admixtured cement. Compared with sea water-treated cement paste, the magnetic susceptibility of ground water-treated cement paste is higher in value. The observed result shows that, irrespective of water, the magnetic susceptibility increases with increasing metakaolin percentage replacement level in cement.展开更多
China's Northern and Southern Dynasties period(3rd–6th centuries AD)marked a significant era of ethnic integration in northern China.However,previous ancient DNA studies have primarily focused on northern ethnic ...China's Northern and Southern Dynasties period(3rd–6th centuries AD)marked a significant era of ethnic integration in northern China.However,previous ancient DNA studies have primarily focused on northern ethnic groups,with limited research on the genetic formation of the hereditary elite family,especially considering their abundant archaeological record and clear material identity.In this study,we obtain the ancient genome of a hereditary elite family,Gao Bin(高宾,503 AD–572 AD),at 0.6473-fold coverage with 475,132 single-nucleotide polymorphisms(SNPs)on the 1240k panel.His mitochondrial haplogroup belongs to Z4 and Y-haplogroup to O1a1a2b-F2444∗.The genetic profile of Gao Bin is most similar to that of the northern Han Chinese.He can be modeled as deriving all his ancestry from Late Neolithic to Iron Age Yellow River farmers without influence from Northeast Asia,Korea,or the Mongolian Plateau.Our study sheds light on the genetic formation of hereditary elite families in the context of the Southern and Northern Dynasties ethnic integration.展开更多
Four typical admixtures,polycarboxylate superplasticiser(PCE),tartaric acid(TA),sorbitol and polyacrylamide(PAM),were selected to systematically investigate their regulatory mechanisms on the formation of ettringite t...Four typical admixtures,polycarboxylate superplasticiser(PCE),tartaric acid(TA),sorbitol and polyacrylamide(PAM),were selected to systematically investigate their regulatory mechanisms on the formation of ettringite through Fourier transform infrared spectroscopy,X-ray diffraction,particle size analysis and nucleation kinetic model.The experimental results indicate that the admixtures alter the formation of ettringite through physical adsorption,complexation and solution viscosity modulation without changing its chemical structure.Low concentrations of PCE inhibit size growth by forming an adsorption layer on the surface of ettringite,whereas high concentrations of PCE alter the size change of ettringite by modulating the distribution of ionic concentrations.TA significantly reduces the size of ettringite by complexing Ca^(2+).Sorbitol and PAM promote the local growth of ettringite at low concentrations,leading to larger sizes.But at high concentrations,the size growth of ettringite is inhibited due to the increase in viscosity or the enhancement of complexation.Matlab nucleation kinetic modelling further shows that the addition of admixtures enhances the initial nucleation during ettringite synthesis,with values ranging from 14.45%to 114.25%.However,the subsequent nucleation rate of ettringite is significantly affected,decreasing by 12.79%to 71.74%.The results provide a theoretical basis for the design of ettringite materials and the optimisation of the application of admixtures.展开更多
An evaluation method for self-healing capacity was designed,which includes the control of initial cracks and subsequent permeability testing.This method was employed to evaluate the self-healing behavior of mortars in...An evaluation method for self-healing capacity was designed,which includes the control of initial cracks and subsequent permeability testing.This method was employed to evaluate the self-healing behavior of mortars incorporating crystalline admixtures(CAs)under various conditions,including water immersion,limewater soaking,and wet-dry cycles,with varying CA dosages and crack widths.The experimental results indicate that cement possesses inherently self-healing capability.Limewater environments inhibits healing compared with water immersion;however,wet-dry cycles enhance the effectiveness of higher CA dosages.Increasing the CA content can not improve healing performance,and wide cracks(0.3 mm)substantially reduce the intrinsic self-healing potential of cement.展开更多
In this paper,the effects of four different mineral ginseng materials on the mechanical properties of mortar were studied,and the results showed that high territory,fly ash,and silica fume had an inhibitory effect on ...In this paper,the effects of four different mineral ginseng materials on the mechanical properties of mortar were studied,and the results showed that high territory,fly ash,and silica fume had an inhibitory effect on the drying shrinkage of mortar,and mineral powder increased the drying shrinkage of mortar.The high territory in the mineral admixture has the best effect on the inhibition of mortar drying shrinkage.The compressive strength and flexural strength of the mortar can be improved by adding a certain amount of mineral admixture,which increases the compressive strength by about 20%-40%and the flexural strength by about 20%-30%compared with the control group,and the improvement effect difference between different components is not large.展开更多
1.In recent years,climate change has led to drought and severe bark beetle infestations,affecting Norway spruce(Picea abies)across Europe,with detrimental consequences for forest owners,the forestry sector and associa...1.In recent years,climate change has led to drought and severe bark beetle infestations,affecting Norway spruce(Picea abies)across Europe,with detrimental consequences for forest owners,the forestry sector and associated industries.As a result,silviculture now faces the challenge of identifying tree species more resilient to these stressors to mitigate the impacts on forest management,forest-dependent economies and rural livelihoods.The North American Douglas-fir(Pseudotsuga menziesii)has emerged as a promising conifer species,better suited to future climate conditions and capable of producing high timber yields.2.Non-native tree species may affect native biodiversity,yet the impacts of Douglas-fir on native forest biodiversity are not clear.A comprehensive review evaluating the impact of Douglas-fir on faunal and floral biodiversity in European forests is lacking.3.Here,we present the results of a systematic literature review on Douglas-fir effects on native biodiversity,focusing on studies conducted in Europe.For arthropods,sufficient studies were found to do more detailed quantitative assessments.For fungi,birds,plants and soil fauna some studies existed,but only qualitative evaluations could be made.Other taxa were not investigated.4.In the present literature,the effects of Douglas-fir inclusion in stands on native biodiversity,compared to stands of solely native tree species,were mostly non-significant(78.6%,based on 32 studies).Positive effects were noted in 12%of cases,while negative effects were observed in 9.4%(total of 1,936 effects).Above-ground fauna was more extensively studied than below-ground fauna.Mechanisms proposed to explain taxa responses were often discussed but not always formally tested.For arthropods,there were varying effects on diversity between studies evaluating different scales(i.e.,tree-scale vs.stand-scale).In general,differences in effects depended on a range of factors,including stand composition and structure,season,and sampling site and period.5.Our review indicates limited evidence of adverse effects of Douglas-fir on biodiversity in European forests,highlighting a significant knowledge gap due to the scarcity of studies.Douglas-fir's impact on biodiversity likely varies depending on the forest type and management practices.Further research in diverse contexts is crucial to determine optimal levels of admixture and guide forest management.展开更多
To mitigate the severe abrasion damage caused by high-velocity water flow in hydraulic engineering applications in Xizang, China, this study systematically optimized key mix design parameters, including aggregate grad...To mitigate the severe abrasion damage caused by high-velocity water flow in hydraulic engineering applications in Xizang, China, this study systematically optimized key mix design parameters, including aggregate gradation, sand ratio, fly ash content, and superplasticizer dosage. Based on the optimized mix, the combined effects of an abrasion-resistance enhancement admixture (AEA) and silica fume (SF) on the abrasion resistance of self-compacting concrete (SCC) were examined. The results demonstrated that the appropriate incorporation of AEA and SF significantly improved the abrasion resistance of SCC without compromising its workability. The proposed mix design not only achieves superior abrasion resistance but also provides practical guidance for the material design and engineering application of durable hydraulic concrete in harsh environments. Future research will focus on comprehensive durability assessments by simulating extreme hydraulic conditions, including sustained exposure to high-velocity sediment-laden flows, repeated freeze-thaw cycles, and corrosive salt spray environments, to thoroughly evaluate the long-term performance evolution of abrasion-resistant self-compacting concrete. Meanwhile, advanced microstructural analytical methods should be applied toelaborate the synergistic mechanisms of abrasion-resistance enhancement admixture (AEA), silica fume (SF), and steel fibers in altering the hydration product formation, optimizing the distribution of pore structure, and strengthening interfacial transition zones, to establish a solid scientific foundation for the development of high-performance composite materials.展开更多
The macroscopic flow behavior and rheological properties of cemented paste backfill(CPB)are highly impacted by the inherent structure of the paste matrix.In this study,the effects of shear-induced forces and proportio...The macroscopic flow behavior and rheological properties of cemented paste backfill(CPB)are highly impacted by the inherent structure of the paste matrix.In this study,the effects of shear-induced forces and proportioning parameters on the microstructure of fresh CPB were studied.The size evolution and distribution of floc/agglomerate/particles of paste were monitored by focused beam reflection measuring(FBRM)technique,and the influencing factors of aggregation and breakage kinetics of CPB were discussed.The results indicate that influenced by both internal and external factors,the paste kinetics evolution covers the dynamic phase and the stable phase.Increasing the mass content or the cement-tailings ratio can accelerate aggregation kinetics,which is advantageous for the rise of average floc size.Besides,the admixture and high shear can improve breaking kinetics,which is beneficial to reduce the average floc size.The chord length resembles a normal distribution somewhat,with a peak value of approximate 20μm.The particle disaggregation con-stant(k_(2))is positively correlated with the agitation rate,and k_(2) is five orders of magnitude greater than the particle aggregation constant(k1).The kinetics model depicts the evolution law of particles over time quantitatively and provides a theoretical foundation for the micromechanics of complicated rheological behavior of paste.展开更多
Water-quenched copper-nickel metallurgical slag enriched with olivine minerals exhibits promising potential for the production of CO_(2)-mineralized cementitious materials.In this work,copper-nickel slag-based cementi...Water-quenched copper-nickel metallurgical slag enriched with olivine minerals exhibits promising potential for the production of CO_(2)-mineralized cementitious materials.In this work,copper-nickel slag-based cementitious material(CNCM)was synthesized by using different chemical activation methods to enhance its hydration reactivity and CO_(2) mineralization capacity.Different water curing ages and carbonation conditions were explored related to their carbonation and mechanical properties development.Meanwhile,thermogravimetry differential scanning calorimetry and X-ray diffraction methods were applied to evaluate the CO_(2) adsorption amount and carbonation products of CNCM.Microstructure development of carbonated CNCM blocks was examined by backscattered electron imaging(BSE)with energy-dispersive X-ray spectrometry.Results showed that among the studied samples,the CNCM sample that was subjected to water curing for 3 d exhibited the highest CO_(2) sequestration amount of 8.51wt%at 80℃and 72 h while presenting the compressive strength of 39.07 MPa.This result indicated that 1 t of this CNCM can sequester 85.1 kg of CO_(2) and exhibit high compressive strength.Although the addition of citric acid did not improve strength development,it was beneficial to increase the CO_(2) diffusion and adsorption amount under the same carbonation conditions from BSE results.This work provides guidance for synthesizing CO_(2)-mineralized cementitious materials using large amounts of metallurgical slags containing olivine minerals.展开更多
This study aimed to investigate the performance evolution characteristics of concrete under permafrost ambient temperatures and to explore methods to mitigate the thermal perturbation by concrete on the permafrost env...This study aimed to investigate the performance evolution characteristics of concrete under permafrost ambient temperatures and to explore methods to mitigate the thermal perturbation by concrete on the permafrost environment.A program was designed to investigate the properties of various concretes at three curing conditions.The compressive strength development pattern of each group was evaluated and the concrete's performance was characterized by compressive strength damage degree,hydration temperature and SEM analysis in a low temperature environment.The experimental results show that the incorporation of fly ash alone or incombination with other admixtures in concrete under low-temperature curing does not deteriorate its microstructure,and at the same time,it can slow down the hydration rate of cement and significantly reduce the exothermic heat of hydration of concrete.These findings are expected to provide valuable references for the proportioning design of concrete in permafrost environments.展开更多
To solve the problems of high rebound rate and strength reversion of shotcrete,a non-fluorine and non-alkaline liquid flash setting admixture(FSN)with low rebound and high early strength was synthesized under 60-65℃w...To solve the problems of high rebound rate and strength reversion of shotcrete,a non-fluorine and non-alkaline liquid flash setting admixture(FSN)with low rebound and high early strength was synthesized under 60-65℃water bath environment through orthogonal test design and taking setting time and compressive strength as indicators.The experimental results show that the optimum mass ratio of FSN is aluminum sulfate:diethanolamine:triethanolamine:pseudo-boehmite:lithium carbonate:water=57%:8%:0.05%:2%:2%:31%.When FSN is added with 7%of the mass of portland cement,the cement paste can be initially set in 3 min and finally set in 5 min.The compressive strength of mortar is 1.2 MPa at 6 h,18.0 MPa at 1 d,and more than 100%at 28 days;The microscopic analysis shows that the rapid release of Li^(+),NH^(4+),and CO_(3)^(2-)ions by FSN in the paste solution effectively shortens the induction period of high C_(3)S content in Portland cement,directly forms early coagulation AFt crystals in FSN and CH dominated by Al_(2)(SO_(4))_(3),and forms a large number of C-S-H gels in the later stage,so that the cement can quickly coagulate and harden,and the strength in the later stage is not retracted.展开更多
With an extended Su–Schrieffer–Heeger model and Green's function method, the spin–orbit coupling(SOC) effects on spin admixture of electronic states and quantum transport in organic devices are investigated. Th...With an extended Su–Schrieffer–Heeger model and Green's function method, the spin–orbit coupling(SOC) effects on spin admixture of electronic states and quantum transport in organic devices are investigated. The role of lattice distortion induced by the strong electron–lattice interaction in organics is clarified in contrast with a uniform chain. The results demonstrate an enhanced SOC effect on the spin admixture of frontier eigenstates by the lattice distortion at a larger SOC,which is explained by the perturbation theory. The quantum transport under the SOC is calculated for both nonmagnetic and ferromagnetic electrodes. A more notable SOC effect on total transmission and current is observed for ferromagnetic electrodes, where spin filtering induced by spin-flipped transmission and suppression of magnetoresistance are obtained.Unlike the spin admixture, a stronger SOC effect on transmission exists for the uniform chain rather than the organic lattices with distortion. The reason is attributed to the modified spin-polarized conducting states in the electrodes by lattice configuration, and hence the spin-flip transmission, instead of the spin admixture of eigenstates. This work is helpful to understand the SOC effect in organic spin valves in the presence of lattice distortion.展开更多
To investigate the influences of different admixtures on the drying shrinkage of polymer mortar in a metakaolin base,the experiments of VAE(vinyl acetate ethylene copolymer),APAM(anionic polyacrylamide)and CPAM(cation...To investigate the influences of different admixtures on the drying shrinkage of polymer mortar in a metakaolin base,the experiments of VAE(vinyl acetate ethylene copolymer),APAM(anionic polyacrylamide)and CPAM(cationic polyacrylamide)on the drying shrinkage properties of geopolymer mortar were designed under normal temperature curing conditions.An SP-175 mortar shrinkage dilatometer was introduced to measure the dry shrinkage of geopolymer mortar.Meanwhile,the drying shrinkage properties of geopolymer mortar are exhibited by the parameters of water loss rate,drying shrinkage rate,drying shrinkage strain and drying shrinkage coefficient.The experimental data are further fitted to obtain the prediction model of dry shrinkage of geopolymer mortar,which can better reflect the relationship between dry shrinkage rate and time.Finally,the experimental results demonstrate that the dry shrinkage of geopolymer mortar can be significantly increased by adding 4%VAE admixture,meanwhile under the condition that the polymer film formed by VAE reaction can strengthen and toughen the mortar.2.5%APAM admixture and 1.5%CPAM admixture can enhance the dry shrinkage performance of geopolymer mortar in a certain range.展开更多
In the present study, we aimed to analyze the irrational medical orders and evaluate the effect of pharmacy intervention on pharmacy intravenous admixture services of outpatient and emergency departments in our hospit...In the present study, we aimed to analyze the irrational medical orders and evaluate the effect of pharmacy intervention on pharmacy intravenous admixture services of outpatient and emergency departments in our hospital. The irrational medical orders of PIVAS at the outpatient and emergency departments were retrospectively analyzed in Jun. 2015. We strengthened the pharmacy intervention on irrational medical orders since July 2015. All the cases were selected by systematic sampling method. Cased studied in Jun. 2015 served as the control group, whereas those studied in Jan. 2016 served as the intervention group. The irrational rate and the irrational number of daily average were compared between the control group and intervention group. The common type of irrational outpatient and emergency intravenous orders mainly included irrational use of solvents, irrational dosing interval and inappropriate compatibility of drugs. The irrational rate was reduced from 17.4% to 3.3% （P〈0.01）, and the irrational number of daily average was decreased from 5.23 to 1.00 （P〈0.01）. Pharmacy intervention can reduce the irrational rate of medical orders in our hospital, which is of great significance to promote rational drug use and improve medical quality.展开更多
In order to investigate the effects of two mineral admixtures （i. e., fly ash and ground slag）on initial defects existing in concrete microstructures, a high-resolution X-ray micro-CT（ micro-focus computer tomogra...In order to investigate the effects of two mineral admixtures （i. e., fly ash and ground slag）on initial defects existing in concrete microstructures, a high-resolution X-ray micro-CT（ micro-focus computer tomography）is employed to quantitatively analyze the initial defects in four series of highperformance concrete （HPC）specimens with additions of different mineral admixtures. The nigh-resolution 3D images of microstructures and filtered defects are reconstructed by micro- CT software. The size distribution and volume fractions of initial defects are analyzed based on 3D and 2D micro-CT images. The analysis results are verified by experimental results of watersuction tests. The results show that the additions of mineral admixtures in concrete as cementitious materials greatly change the geometrical properties of the microstructures and the spatial features of defects by physical-chemistry actions of these mineral admixtures. This is the major cause of the differences between the mechanical behaviors of HPC with and without mineral admixtures when the water-to-binder ratio and the size distribution of aggregates are constant.展开更多
In order to reduce the cohesive force between pavement and ice, the approach of pavement surface coating with hydrophobic admixtures is investigated. The deicing effect of this approach is examined by the contact angl...In order to reduce the cohesive force between pavement and ice, the approach of pavement surface coating with hydrophobic admixtures is investigated. The deicing effect of this approach is examined by the contact angle test and the shear test. The durability of the approach is examined by the accelerated abrasion test, and the skid resistance of the pavement with surface coating is examined by the British pendulum test and the surface texture depth test. In the contact angle test, the contact angle between hydrophobic admixture and water is 100.2°. In the shear test, the maximum shear stress is 0.06 MPa for the specimen coated with hydrophobic admixture, which is much lower than that of the specimen without hydrophobic admixture coating, 3.5 MPa. Furth- ermore, the ice and asphalt surface are completely separated for the coated specimen while not for the uncoated specimen. Based on the accelerated abrasion test, the residual hydro- phobic admixture in the veins of the pavement after abrasion still has a deicing effect. From the skid resistance tests, the British pendulum number （BPN） and the texture depth （TD） of the specimen coated with hydrophobic admixtures are larger than those of the standard requirements. The overall experi-mental observation indicates that the approach can effectively reduce close contact between asphalt pavement and ice; therefore, it can be a promising solution to road icing problems in winter.展开更多
文摘The role of metakaolin in the properties of Portland cement hydrated with ground water and sea water was described by magnetic susceptibility study. Cement pastes containing 0wt%, 10wt%, 20wt% and 30wt% replacement of metakaolin and in a water/cement （W/C） ratio of 0.4 were prepared. The susceptibility at different hydration periods was determined by Faraday Curie balance and it was related to the changes in setting time and compressive strength of admixtured cement. Compared with sea water-treated cement paste, the magnetic susceptibility of ground water-treated cement paste is higher in value. The observed result shows that, irrespective of water, the magnetic susceptibility increases with increasing metakaolin percentage replacement level in cement.
基金funded by the National Natural Science Foundation of China(32070576,31801040,and 32270667)Lantai Young Scholars Program of Chinese History Institute(2022LTQN602)+11 种基金the National Social Science Fund of China(19VJX074 and 21CKG022)Priority Research Program of the Chinese Academy of Sciences:Pan-Third Pole Environment Study for a Green Silk Road(Pan-TPE)(XDA2004010101)the National Key Research and Development Program(2023YFC3303701-02)the Natural Science Foundation of Fujian Province of China(2023J06013)the Science and Technology Commission of Shanghai Municipality(18490750300)the National Key Research and Development Program(2020YFE0201600)Shanghai Municipal Science and Technology Major Project(2017SHZDZX01)the Major Project of National Social Science Foundation of China granted to C.C.W.(21&ZD285),S.W.(20&ZD212),and D.L.(21&ZD237)Major Special Project of Philosophy and Social Sciences Research of the Ministry of Education(2022JZDZ023)Open Research Fund of State Key Laboratory of Genetic Engineering at Fudan University(SKLGE-2310)Open Research Fund of Forensic Genetics Key Laboratory of the Ministry of Public Security(2023FGKFKT07)European Research Council(ERC)grant(ERC-2019-ADG-883700-TRAM).
文摘China's Northern and Southern Dynasties period(3rd–6th centuries AD)marked a significant era of ethnic integration in northern China.However,previous ancient DNA studies have primarily focused on northern ethnic groups,with limited research on the genetic formation of the hereditary elite family,especially considering their abundant archaeological record and clear material identity.In this study,we obtain the ancient genome of a hereditary elite family,Gao Bin(高宾,503 AD–572 AD),at 0.6473-fold coverage with 475,132 single-nucleotide polymorphisms(SNPs)on the 1240k panel.His mitochondrial haplogroup belongs to Z4 and Y-haplogroup to O1a1a2b-F2444∗.The genetic profile of Gao Bin is most similar to that of the northern Han Chinese.He can be modeled as deriving all his ancestry from Late Neolithic to Iron Age Yellow River farmers without influence from Northeast Asia,Korea,or the Mongolian Plateau.Our study sheds light on the genetic formation of hereditary elite families in the context of the Southern and Northern Dynasties ethnic integration.
基金Funded by the National Natural Science Foundation of China(Nos.51578412,51878479,52078372,and 52478272)the International Science and Technology Cooperation Project of the Key R&D Program of Science and Technology Innovation Yongjiang 2035(No.2024H023)。
文摘Four typical admixtures,polycarboxylate superplasticiser(PCE),tartaric acid(TA),sorbitol and polyacrylamide(PAM),were selected to systematically investigate their regulatory mechanisms on the formation of ettringite through Fourier transform infrared spectroscopy,X-ray diffraction,particle size analysis and nucleation kinetic model.The experimental results indicate that the admixtures alter the formation of ettringite through physical adsorption,complexation and solution viscosity modulation without changing its chemical structure.Low concentrations of PCE inhibit size growth by forming an adsorption layer on the surface of ettringite,whereas high concentrations of PCE alter the size change of ettringite by modulating the distribution of ionic concentrations.TA significantly reduces the size of ettringite by complexing Ca^(2+).Sorbitol and PAM promote the local growth of ettringite at low concentrations,leading to larger sizes.But at high concentrations,the size growth of ettringite is inhibited due to the increase in viscosity or the enhancement of complexation.Matlab nucleation kinetic modelling further shows that the addition of admixtures enhances the initial nucleation during ettringite synthesis,with values ranging from 14.45%to 114.25%.However,the subsequent nucleation rate of ettringite is significantly affected,decreasing by 12.79%to 71.74%.The results provide a theoretical basis for the design of ettringite materials and the optimisation of the application of admixtures.
基金Funded by the International Science and Technology Cooperation Project of the Key R&D Program of Science and Technology Innovation Yongjiang 2035。
文摘An evaluation method for self-healing capacity was designed,which includes the control of initial cracks and subsequent permeability testing.This method was employed to evaluate the self-healing behavior of mortars incorporating crystalline admixtures(CAs)under various conditions,including water immersion,limewater soaking,and wet-dry cycles,with varying CA dosages and crack widths.The experimental results indicate that cement possesses inherently self-healing capability.Limewater environments inhibits healing compared with water immersion;however,wet-dry cycles enhance the effectiveness of higher CA dosages.Increasing the CA content can not improve healing performance,and wide cracks(0.3 mm)substantially reduce the intrinsic self-healing potential of cement.
基金Hunan Provincial Department of Water Resources:Research on Formula Optimization and Performance Evaluation System of Ecological Concrete for River Water Quality Purification Based on the Dual Carbon Goal(Project No.:XSKJ2024064-44)。
文摘In this paper,the effects of four different mineral ginseng materials on the mechanical properties of mortar were studied,and the results showed that high territory,fly ash,and silica fume had an inhibitory effect on the drying shrinkage of mortar,and mineral powder increased the drying shrinkage of mortar.The high territory in the mineral admixture has the best effect on the inhibition of mortar drying shrinkage.The compressive strength and flexural strength of the mortar can be improved by adding a certain amount of mineral admixture,which increases the compressive strength by about 20%-40%and the flexural strength by about 20%-30%compared with the control group,and the improvement effect difference between different components is not large.
基金supported by grant klifW018 of the Bavarian State Ministry for Food,Agriculture and Forestry for funding.
文摘1.In recent years,climate change has led to drought and severe bark beetle infestations,affecting Norway spruce(Picea abies)across Europe,with detrimental consequences for forest owners,the forestry sector and associated industries.As a result,silviculture now faces the challenge of identifying tree species more resilient to these stressors to mitigate the impacts on forest management,forest-dependent economies and rural livelihoods.The North American Douglas-fir(Pseudotsuga menziesii)has emerged as a promising conifer species,better suited to future climate conditions and capable of producing high timber yields.2.Non-native tree species may affect native biodiversity,yet the impacts of Douglas-fir on native forest biodiversity are not clear.A comprehensive review evaluating the impact of Douglas-fir on faunal and floral biodiversity in European forests is lacking.3.Here,we present the results of a systematic literature review on Douglas-fir effects on native biodiversity,focusing on studies conducted in Europe.For arthropods,sufficient studies were found to do more detailed quantitative assessments.For fungi,birds,plants and soil fauna some studies existed,but only qualitative evaluations could be made.Other taxa were not investigated.4.In the present literature,the effects of Douglas-fir inclusion in stands on native biodiversity,compared to stands of solely native tree species,were mostly non-significant(78.6%,based on 32 studies).Positive effects were noted in 12%of cases,while negative effects were observed in 9.4%(total of 1,936 effects).Above-ground fauna was more extensively studied than below-ground fauna.Mechanisms proposed to explain taxa responses were often discussed but not always formally tested.For arthropods,there were varying effects on diversity between studies evaluating different scales(i.e.,tree-scale vs.stand-scale).In general,differences in effects depended on a range of factors,including stand composition and structure,season,and sampling site and period.5.Our review indicates limited evidence of adverse effects of Douglas-fir on biodiversity in European forests,highlighting a significant knowledge gap due to the scarcity of studies.Douglas-fir's impact on biodiversity likely varies depending on the forest type and management practices.Further research in diverse contexts is crucial to determine optimal levels of admixture and guide forest management.
基金supported by the National Natural Science Foundation of China(No.52179137).
文摘To mitigate the severe abrasion damage caused by high-velocity water flow in hydraulic engineering applications in Xizang, China, this study systematically optimized key mix design parameters, including aggregate gradation, sand ratio, fly ash content, and superplasticizer dosage. Based on the optimized mix, the combined effects of an abrasion-resistance enhancement admixture (AEA) and silica fume (SF) on the abrasion resistance of self-compacting concrete (SCC) were examined. The results demonstrated that the appropriate incorporation of AEA and SF significantly improved the abrasion resistance of SCC without compromising its workability. The proposed mix design not only achieves superior abrasion resistance but also provides practical guidance for the material design and engineering application of durable hydraulic concrete in harsh environments. Future research will focus on comprehensive durability assessments by simulating extreme hydraulic conditions, including sustained exposure to high-velocity sediment-laden flows, repeated freeze-thaw cycles, and corrosive salt spray environments, to thoroughly evaluate the long-term performance evolution of abrasion-resistant self-compacting concrete. Meanwhile, advanced microstructural analytical methods should be applied toelaborate the synergistic mechanisms of abrasion-resistance enhancement admixture (AEA), silica fume (SF), and steel fibers in altering the hydration product formation, optimizing the distribution of pore structure, and strengthening interfacial transition zones, to establish a solid scientific foundation for the development of high-performance composite materials.
基金financially supported by the National Natural Science Foundation of China(No.52104129)the Shandong Provincial Major Science and Technology Innovation Project,China(No.2019SDZY05)+2 种基金the key Laboratory of Mine Ecological Effects and Systematic Restoration,Ministry of Natural Resources(No.MEER-2022-09)the Double First-class Construction Project in Henan Province,China(No.AQ20230735)the Doctoral Fund of Henan Polytechnic University(No.B2021-59).
文摘The macroscopic flow behavior and rheological properties of cemented paste backfill(CPB)are highly impacted by the inherent structure of the paste matrix.In this study,the effects of shear-induced forces and proportioning parameters on the microstructure of fresh CPB were studied.The size evolution and distribution of floc/agglomerate/particles of paste were monitored by focused beam reflection measuring(FBRM)technique,and the influencing factors of aggregation and breakage kinetics of CPB were discussed.The results indicate that influenced by both internal and external factors,the paste kinetics evolution covers the dynamic phase and the stable phase.Increasing the mass content or the cement-tailings ratio can accelerate aggregation kinetics,which is advantageous for the rise of average floc size.Besides,the admixture and high shear can improve breaking kinetics,which is beneficial to reduce the average floc size.The chord length resembles a normal distribution somewhat,with a peak value of approximate 20μm.The particle disaggregation con-stant(k_(2))is positively correlated with the agitation rate,and k_(2) is five orders of magnitude greater than the particle aggregation constant(k1).The kinetics model depicts the evolution law of particles over time quantitatively and provides a theoretical foundation for the micromechanics of complicated rheological behavior of paste.
基金supported by the Intergovernmental International Science and Technology Innovation Cooperation Key Project of the National Key Research and Development Program of China (No.2022YFE0135100)the National Natural Science Foundation of China (No.52072171)+1 种基金the Beijing Nova Program (No.20220484057)the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD).
文摘Water-quenched copper-nickel metallurgical slag enriched with olivine minerals exhibits promising potential for the production of CO_(2)-mineralized cementitious materials.In this work,copper-nickel slag-based cementitious material(CNCM)was synthesized by using different chemical activation methods to enhance its hydration reactivity and CO_(2) mineralization capacity.Different water curing ages and carbonation conditions were explored related to their carbonation and mechanical properties development.Meanwhile,thermogravimetry differential scanning calorimetry and X-ray diffraction methods were applied to evaluate the CO_(2) adsorption amount and carbonation products of CNCM.Microstructure development of carbonated CNCM blocks was examined by backscattered electron imaging(BSE)with energy-dispersive X-ray spectrometry.Results showed that among the studied samples,the CNCM sample that was subjected to water curing for 3 d exhibited the highest CO_(2) sequestration amount of 8.51wt%at 80℃and 72 h while presenting the compressive strength of 39.07 MPa.This result indicated that 1 t of this CNCM can sequester 85.1 kg of CO_(2) and exhibit high compressive strength.Although the addition of citric acid did not improve strength development,it was beneficial to increase the CO_(2) diffusion and adsorption amount under the same carbonation conditions from BSE results.This work provides guidance for synthesizing CO_(2)-mineralized cementitious materials using large amounts of metallurgical slags containing olivine minerals.
基金Funded by the National Natural Science Foundation of China(Nos.52068035,52078372,and 52478272)。
文摘This study aimed to investigate the performance evolution characteristics of concrete under permafrost ambient temperatures and to explore methods to mitigate the thermal perturbation by concrete on the permafrost environment.A program was designed to investigate the properties of various concretes at three curing conditions.The compressive strength development pattern of each group was evaluated and the concrete's performance was characterized by compressive strength damage degree,hydration temperature and SEM analysis in a low temperature environment.The experimental results show that the incorporation of fly ash alone or incombination with other admixtures in concrete under low-temperature curing does not deteriorate its microstructure,and at the same time,it can slow down the hydration rate of cement and significantly reduce the exothermic heat of hydration of concrete.These findings are expected to provide valuable references for the proportioning design of concrete in permafrost environments.
基金Funded by the National Key Research and Development Program of China(No.2021YFB2601200)the Natural Science Foundations of Hebei Province(No.E2022210103)。
文摘To solve the problems of high rebound rate and strength reversion of shotcrete,a non-fluorine and non-alkaline liquid flash setting admixture(FSN)with low rebound and high early strength was synthesized under 60-65℃water bath environment through orthogonal test design and taking setting time and compressive strength as indicators.The experimental results show that the optimum mass ratio of FSN is aluminum sulfate:diethanolamine:triethanolamine:pseudo-boehmite:lithium carbonate:water=57%:8%:0.05%:2%:2%:31%.When FSN is added with 7%of the mass of portland cement,the cement paste can be initially set in 3 min and finally set in 5 min.The compressive strength of mortar is 1.2 MPa at 6 h,18.0 MPa at 1 d,and more than 100%at 28 days;The microscopic analysis shows that the rapid release of Li^(+),NH^(4+),and CO_(3)^(2-)ions by FSN in the paste solution effectively shortens the induction period of high C_(3)S content in Portland cement,directly forms early coagulation AFt crystals in FSN and CH dominated by Al_(2)(SO_(4))_(3),and forms a large number of C-S-H gels in the later stage,so that the cement can quickly coagulate and harden,and the strength in the later stage is not retracted.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11974215,21933002,and 12274264)。
文摘With an extended Su–Schrieffer–Heeger model and Green's function method, the spin–orbit coupling(SOC) effects on spin admixture of electronic states and quantum transport in organic devices are investigated. The role of lattice distortion induced by the strong electron–lattice interaction in organics is clarified in contrast with a uniform chain. The results demonstrate an enhanced SOC effect on the spin admixture of frontier eigenstates by the lattice distortion at a larger SOC,which is explained by the perturbation theory. The quantum transport under the SOC is calculated for both nonmagnetic and ferromagnetic electrodes. A more notable SOC effect on total transmission and current is observed for ferromagnetic electrodes, where spin filtering induced by spin-flipped transmission and suppression of magnetoresistance are obtained.Unlike the spin admixture, a stronger SOC effect on transmission exists for the uniform chain rather than the organic lattices with distortion. The reason is attributed to the modified spin-polarized conducting states in the electrodes by lattice configuration, and hence the spin-flip transmission, instead of the spin admixture of eigenstates. This work is helpful to understand the SOC effect in organic spin valves in the presence of lattice distortion.
基金Funded by the the Shaanxi Provincial Natural Science Basic Research Plan(No.2021JQ-471)the Natural Science Project of Shaanxi Provincial Department of Education(No.21JK0802)。
文摘To investigate the influences of different admixtures on the drying shrinkage of polymer mortar in a metakaolin base,the experiments of VAE(vinyl acetate ethylene copolymer),APAM(anionic polyacrylamide)and CPAM(cationic polyacrylamide)on the drying shrinkage properties of geopolymer mortar were designed under normal temperature curing conditions.An SP-175 mortar shrinkage dilatometer was introduced to measure the dry shrinkage of geopolymer mortar.Meanwhile,the drying shrinkage properties of geopolymer mortar are exhibited by the parameters of water loss rate,drying shrinkage rate,drying shrinkage strain and drying shrinkage coefficient.The experimental data are further fitted to obtain the prediction model of dry shrinkage of geopolymer mortar,which can better reflect the relationship between dry shrinkage rate and time.Finally,the experimental results demonstrate that the dry shrinkage of geopolymer mortar can be significantly increased by adding 4%VAE admixture,meanwhile under the condition that the polymer film formed by VAE reaction can strengthen and toughen the mortar.2.5%APAM admixture and 1.5%CPAM admixture can enhance the dry shrinkage performance of geopolymer mortar in a certain range.
文摘In the present study, we aimed to analyze the irrational medical orders and evaluate the effect of pharmacy intervention on pharmacy intravenous admixture services of outpatient and emergency departments in our hospital. The irrational medical orders of PIVAS at the outpatient and emergency departments were retrospectively analyzed in Jun. 2015. We strengthened the pharmacy intervention on irrational medical orders since July 2015. All the cases were selected by systematic sampling method. Cased studied in Jun. 2015 served as the control group, whereas those studied in Jan. 2016 served as the intervention group. The irrational rate and the irrational number of daily average were compared between the control group and intervention group. The common type of irrational outpatient and emergency intravenous orders mainly included irrational use of solvents, irrational dosing interval and inappropriate compatibility of drugs. The irrational rate was reduced from 17.4% to 3.3% （P〈0.01）, and the irrational number of daily average was decreased from 5.23 to 1.00 （P〈0.01）. Pharmacy intervention can reduce the irrational rate of medical orders in our hospital, which is of great significance to promote rational drug use and improve medical quality.
基金The Scholarship Supported by Ministry of Education of China for Research Abroad(No.3037[2006])the Excellent Doctoral Dissertation Foundation of Southeast University (No.YBTJ-0512)the National Basic Research Program of China(973Program)(No.2009CB623203)
文摘In order to investigate the effects of two mineral admixtures （i. e., fly ash and ground slag）on initial defects existing in concrete microstructures, a high-resolution X-ray micro-CT（ micro-focus computer tomography）is employed to quantitatively analyze the initial defects in four series of highperformance concrete （HPC）specimens with additions of different mineral admixtures. The nigh-resolution 3D images of microstructures and filtered defects are reconstructed by micro- CT software. The size distribution and volume fractions of initial defects are analyzed based on 3D and 2D micro-CT images. The analysis results are verified by experimental results of watersuction tests. The results show that the additions of mineral admixtures in concrete as cementitious materials greatly change the geometrical properties of the microstructures and the spatial features of defects by physical-chemistry actions of these mineral admixtures. This is the major cause of the differences between the mechanical behaviors of HPC with and without mineral admixtures when the water-to-binder ratio and the size distribution of aggregates are constant.
文摘In order to reduce the cohesive force between pavement and ice, the approach of pavement surface coating with hydrophobic admixtures is investigated. The deicing effect of this approach is examined by the contact angle test and the shear test. The durability of the approach is examined by the accelerated abrasion test, and the skid resistance of the pavement with surface coating is examined by the British pendulum test and the surface texture depth test. In the contact angle test, the contact angle between hydrophobic admixture and water is 100.2°. In the shear test, the maximum shear stress is 0.06 MPa for the specimen coated with hydrophobic admixture, which is much lower than that of the specimen without hydrophobic admixture coating, 3.5 MPa. Furth- ermore, the ice and asphalt surface are completely separated for the coated specimen while not for the uncoated specimen. Based on the accelerated abrasion test, the residual hydro- phobic admixture in the veins of the pavement after abrasion still has a deicing effect. From the skid resistance tests, the British pendulum number （BPN） and the texture depth （TD） of the specimen coated with hydrophobic admixtures are larger than those of the standard requirements. The overall experi-mental observation indicates that the approach can effectively reduce close contact between asphalt pavement and ice; therefore, it can be a promising solution to road icing problems in winter.
