In this study, 13 strong-gluten wheat varieties screened by the Key Project of Modern Agricultural Industry Technology System ＂Study on Industrial Technology for Strong-gluten Wheat from Lime Concretion Black Soil Ar...In this study, 13 strong-gluten wheat varieties screened by the Key Project of Modern Agricultural Industry Technology System ＂Study on Industrial Technology for Strong-gluten Wheat from Lime Concretion Black Soil Area in the Huanghuai Wheat Region＂ were used as experimental materials to investigate their bread-making quality, noodle-making quality and other related characteristics. The results showed that more than half of the wheat varieties had better bread-making quality; the bread made from wheat with longer dough mixing time than 3.0 min had better texture, lighter color, and better taste. All these 13 strong-gluten wheat varieties showed good noodle-making quality in color, appearance, smoothness and taste; the differences between varieties were mainly found in palatability and viscoelasticity. Jimai 20, Xinong 979, Zhengmai 7698, Ji＇nan 17 and Zhengmai 9023 exhibited excellent bread-making quality; Zhengmai 366, Jimai 20 and Xinong 979 displayed excellent noodle-making quality. Fresh dough sheets made from Zhengmai 366, Jimai 20 and Xinong 979 exhibited slight color variation within 24 h and high peak starch paste viscosity; dry and cooked noodles made from Zhengmai 366, Jimai 20 and Xinong 979 had good quality.展开更多
Carbonate concretions are conspicuous in organic-rich shales and are generally related to decomposition of organic matter.The black shales from the Chang 7 Member of the Upper Triassic Yanchang Formation of the southe...Carbonate concretions are conspicuous in organic-rich shales and are generally related to decomposition of organic matter.The black shales from the Chang 7 Member of the Upper Triassic Yanchang Formation of the southern Ordos Basin host abundant carbonate concretions,which provide a unique record of depositional and early diagenetic conditions of the paleo-lake sediments.However,little attention has been given to the genesis and growth processes of the concretions in these lacustrine petroleum source rocks.New petrographic observations and geochemical analysis show that the concretions are composed of calcite,phosphate fossil fragments,K-NH4-feldspar,quartz,bitumen,and minor Fe-dolomite.Phosphate minerals,mainly carbonate fluorapatite(CFA),show pervasive replacement by calcite,most of which contains phosphorus,ranging in concentration from 0.26 to 2.35 wt%.This suggests that the phosphate minerals are the precursors for concretion growth.Positiveδ13C(+5.6 to+12.4‰V-PDB)signatures and the absence of pyrite indicate that microbial methanogenesis was the dominant driver for concretion growth,rather than bacterial sulfate reduction.Quartz,bitumen,and Fe-dolomite are the last cements that occurred,at deep burial depths and high temperatures.The formation of phosphate minerals might have been induced by upwelling of phosphate-enriched deep water in the Late Triassic paleo-lake,which promoted phytoplankton blooms and further enrichment of organic matter.Extremely slow sedimentation rates of fine-grained detrital minerals,relative to dead organism accumulation,led to the high permeabilities of the organic-rich sediments and rapid concretion growth during shallow burial.The close association of phosphate-bearing carbonate concretions and organic-rich shales reflects that upwelling played a critical role in the formation of the high-quality petroleum source rocks in the Triassic paleo-Ordos lake.展开更多
The Early Cambrian Niutitang Formation is characterized by wide distribution of black shales on Yangtze Block,South China.Here we have reported the pyrite concretions in the bottom of the Niutitang Formation deposited...The Early Cambrian Niutitang Formation is characterized by wide distribution of black shales on Yangtze Block,South China.Here we have reported the pyrite concretions in the bottom of the Niutitang Formation deposited in the slope-basin environment of Yangtze Block.The pyrite concretion was mainly composed of pyrite associated with hydrothermal minerals(barite,hyalophane,tetrahedrite),followed by quartz and organic matter.Trace elements Mo and U displayed significant enrichment(enrichment factors > 10),indicating the euxinic bottom water condition.Cu,Ni,and excess Ba concentrations were relatively high,denoting high primary productivity.In-situ sulfur isotope compositions of pyrite concretions δ34Spy) showed little variations(13.2‰–19.4‰) and small fractionations compared to coeval seawater δ34Sso4.Petrological and geochemical analyses indicated the pyrite concretions were formed in the sediment-water interface during the early diagenesis,with H2S diffusing from the euxinic water,and influenced by hydrothermal activity leading to the coexistence of barite,hyalophane,and tetrahedrite.These results imply euxinic bottom water featured by high primary productivity and increasing riverine flux of sulfate from chemical weathering during the Early Cambrian.展开更多
Under the condition of thick alluvia, there is biggish declination in predicting the coal mining subsidence by commonly strip design method compared with the practical observation, the sinkage is much smaller. Based o...Under the condition of thick alluvia, there is biggish declination in predicting the coal mining subsidence by commonly strip design method compared with the practical observation, the sinkage is much smaller. Based on the method of the probability integral about coal mining subsidence calculation, discussed the surface subsidence calculation and deduced the formulas caused by the clay with dewatering. The results show that the clay dewatering has great impact on surface subsidence. Therefore, the clay dewatering on surface subsidence should not be overlooked.展开更多
To analyze the bacterial communities in lime concretion black soil upon the incorporation of crop residues for two years in wheat-maize system, total DNA was directly extracted and PCR-amplified with the F357GC and R5...To analyze the bacterial communities in lime concretion black soil upon the incorporation of crop residues for two years in wheat-maize system, total DNA was directly extracted and PCR-amplified with the F357GC and R518 primers targeting the 16S rRNA genes of V3 region. The amplified fragments were analyzed by perpendicular DGGE. Analyzing of species richness index S and Shannon diversity index H revealed that there was a high diversity of soil bacterial community compositions among all treatments after incorporation of crop residues and fertilizing under field conditions. Eleven DGGE bands recovered were re-amplified, sequenced. Phylogenetic analysis of the representative DGGE fingerprints identified four groups of the prokaryotic communities in the soil by returning wheat residues and fertilizing under field conditions. The bacterial communities belonged to gamma proteobacterium, Cupriavidus sp, halophilic eubacterium, Acidobacterium sp, Sorangium sp, delta proteobacterium, Streptococcus sp and Streptococcus agalactiae were main bacterial communities. Principal Component Analysis (PCA) showed that there were the differences in DNA profiles among the six treatments. It showed that wheat residue returning, maize residue returning and fertilizing all can improve bacterial diversity in varying degrees. As far as improvement of bacterial diversity was concerned, wheat residue returning was higher than fertilizing, and fertilizing higher than maize residue returning.展开更多
Mineralogical and textural characteristics and organic carbon composition of the carbonate concretions from the upper Doushantuo Formation (ca. 551 Ma) in the eastern Yangtze Gorge area reveal their early diagenetic (...Mineralogical and textural characteristics and organic carbon composition of the carbonate concretions from the upper Doushantuo Formation (ca. 551 Ma) in the eastern Yangtze Gorge area reveal their early diagenetic (shallow) growth in organic-rich shale. High organic carbon content (up to 10%) and abundance of framboidal pyrites in the hosting shale suggest an anoxic or euxinic depositional environment. Well-preserved cardhouse clay fabrics in the concretions suggest their formation at 0-3 m burial depth, likely associated with microbial decomposition of organic matter and anaerobic oxidation of methane. Gases through decomposition of organic matter and/or from methanogenesis created bubbles and cavities, and anaerobic methane oxidation at the sulfate reduction zone resulted in carbonate precipitation, filling in bubbles and cavities to form spherical structures of the concretions. Rock pyrolysis analyses show that the carbonate concretions have lower total organic carbon (TOC) content but higher effective carbon than those in the host rocks. This may be caused by enclosed organic matter in pores of the concretions so that organic matter was protected from further modification during deep burial and maintained high hydrocarbon generating potential even in over-matured source rock. As a microbialite sensu latu, concretions have special growth conditions and may provide important information on the microbial activities in depositional and early burial environments.展开更多
Carbonate concretions provide unique records of ancient biogeochemical processes in marine sediments, and have the potential to reflect seawater chemistry indirectly. In fine-siliciclastic settings, they preferentiall...Carbonate concretions provide unique records of ancient biogeochemical processes in marine sediments, and have the potential to reflect seawater chemistry indirectly. In fine-siliciclastic settings, they preferentially form in organicrich mudstones, owing to a significant fraction of the bicarbonate required for carbonate precipitation resulted from the decomposition of organic matter in sediments. In the Member IV of the Xiamaling Formation(ca. 1.40–1.35 Ga), North China, however, carbonate concretions occur in organic-poor green silty shales(avg. TOC = ~ 0.1 wt%).In order to elucidate the mechanism of the concretion formation and their environmental implications, a thorough study on the petrographic and geochemical compositions of the concretions and their host rocks was conducted.Macro-to microscopic fabrics, including deformed shale laminae surrounding the concretions, "cardhouse"structures of clay minerals and calcite geodes in the concretions, indicate that these concretions are of early diagenetic origin prior to the significant compaction of clay minerals. The carbon isotope compositions of the concretions(-1.7‰ to + 1.5‰) are stable and close to or slightly lower than that of the contemporaneous seawater, indicating that the bicarbonates required for the concretion formation were mainly sourced from seawater by diffusion rather than produced by methanogenesis or anoxic oxidation of methane(AOM); the rare occurrence of authigenic pyrite grains in the concretions likely indicates that bacterial sulfate reduction(BSR) did not play a significant role in their formation either. Almost all the calcite in the concretions has low Mn–Fe in nuclei but high Mn–Fe in rims with average Mn/Fe ratio close to 3.3. The calcite shows positive Ce anomalies(avg. 1.43)and low Y/Ho ratios(avg. 31). This evidence suggests that Mn reduction is the dominant process responsible for the formation of calcite rims while nitrate reduction probably triggered the precipitation of calcite nuclei.Prominence of Mn reduction in the porewater likely indicates that there was sufficient oxygen to support active Mn-redox cycling in the overlying seawater.展开更多
In an attempt to provide more data about the mechanics of transition metal occurrence and translocation in soil environments, Fe-Mn concretions are separated from bulk samples of representative soil types and the elem...In an attempt to provide more data about the mechanics of transition metal occurrence and translocation in soil environments, Fe-Mn concretions are separated from bulk samples of representative soil types and the element contents are determined. The results are reported and discussed in the sense of environmental geochemistry in this article.展开更多
This study introduces superabsorbent polymers(SAP)into recycled concrete and,through freeze-thaw cycle tests,unconfined compressive strength tests,and nuclear magnetic resonance(NMR)analysis,evaluates the freeze-thaw ...This study introduces superabsorbent polymers(SAP)into recycled concrete and,through freeze-thaw cycle tests,unconfined compressive strength tests,and nuclear magnetic resonance(NMR)analysis,evaluates the freeze-thaw resistance and durability of recycled concrete samples under varying freeze-thaw cycles.The results indicate that an appropriate addition of SAP significantly enhances the freeze-thaw resistance of recycled concrete.After 200 freeze-thaw cycles,the RS0.6 sample retained good surface integrity,demonstrating the best performance.Compared to NAC,its mass loss decreased by 1.16%,the relative dynamic modulus improved by 7.01%,and the compressive strength loss rate decreased by 5.41%.Additionally,T2 spectrum analysis revealed that adding SAP optimized the pore structure of recycled concrete and mitigated pore development during freeze-thaw cycles.As the number of freeze-thaw cycles increased,the RS0.3 and RS0.6 samples demonstrated superior frost resistance compared to NAC.However,an excessive amount of SAP increased pore expansion during subsequent freeze-thaw cycles,ultimately weakening frost resistance.展开更多
We investigated the effects of fly ash(FA)content on the mechanical properties of recycled aggregate concrete(RAC)and its regeneration potential under freeze and thaw(F-T)cycles.The physical properties of second-gener...We investigated the effects of fly ash(FA)content on the mechanical properties of recycled aggregate concrete(RAC)and its regeneration potential under freeze and thaw(F-T)cycles.The physical properties of second-generation recycled concrete aggregates(RCA)were used to analyze the regeneration potential of RAC after F-T cycles.Scanning electron microscopy was used to study the interfacial transition zone microstructure of RAC after F-T cycles.Results showed that adding 20%FA to RAC significantly enhanced its mechanical properties and frost resistance.Before the F-T cycles,the compressive strength of RAC with 20%FA reached 48.3 MPa,exceeding research strength target of 40 MPa.A majority of second-generation RCA with FA had been verified to attain class Ⅲ,which enabled their practical application in non-structural projects such as backfill trenches and road pavement.However,the second-generation RCA with 20%FA can achieve class Ⅱ,making it ideal for 40 MPa structural concrete.展开更多
The engineering application of low-alkali sulphoaluminate cement(L-SAC)is hindered due to the difficulty in adjusting the setting and hardening time.In this paper,lithium hydroxide and borax are mixed into L-SAC to re...The engineering application of low-alkali sulphoaluminate cement(L-SAC)is hindered due to the difficulty in adjusting the setting and hardening time.In this paper,lithium hydroxide and borax are mixed into L-SAC to regulate its setting and hardening process,so as to prepare a sulphoaluminate concrete material with high early strength and high fluidity.The effects of the ratio of lithium hydroxide to borax on the properties of L-SAC concrete were studied by hydration heat,XRD,TG-DTG,SEM and MIP.The experimental results show that the slump increases with the increase of borax content,and the early(3 h)strength increases with the increase of lithium hydroxide content.When 0.05% lithium hydroxide and 0.4% borax are added,the 0.5 h slump reaches 195 mm,and the 3 h compressive strength reaches 15.9 MPa.The increase of lithium hydroxide will promote the formation of early hydration products AFt and AH3 gel and accelerate the hydration process,while borax will inhibit the dissolution and hydration of cement and delay the setting and hardening process of concrete.The combination of the two ensures that the concrete has the characteristics of high early strength and high fluidity,and the early workability and mechanical properties can be controlled by the mix ratio.For long-term mechanical properties,the special concrete does not produce AFm,which can ensure the continuous development of strength.展开更多
Based on the split hopkinson pressure bar(SHPB)tests results,the cubic specimens have been numerically modeled in this paper to investigate the impact of key factors,such as the rise time,duration,and incident pulse s...Based on the split hopkinson pressure bar(SHPB)tests results,the cubic specimens have been numerically modeled in this paper to investigate the impact of key factors,such as the rise time,duration,and incident pulse shape,on achieving stress uniformity.After analysis,the paper provides actionable methods aimed at optimizing the conditions for stress uniformity within the cubic specimen.Finally,the lateral inertia effect of cubic specimen has been scrutinized to address the existing gap in this academic area.展开更多
Accurate prediction of concrete compressive strength is fundamental for optimizing mix designs,improving material utilization,and ensuring structural safety in modern construction.Traditional empirical methods often f...Accurate prediction of concrete compressive strength is fundamental for optimizing mix designs,improving material utilization,and ensuring structural safety in modern construction.Traditional empirical methods often fail to capture the non-linear relationships among concrete constituents,especially with the growing use of supple-mentary cementitious materials and recycled aggregates.This study presents an integrated machine learning framework for concrete strength prediction,combining advanced regression models—namely CatBoost—with metaheuristic optimization algorithms,with a particular focus on the Somersaulting Spider Optimizer(SSO).A comprehensive dataset encompassing diverse mix proportions and material types was used to evaluate baseline machine learning models,including CatBoost,XGBoost,ExtraTrees,and RandomForest.Among these,CatBoost demonstrated superior accuracy across multiple performance metrics.To further enhance predictive capability,several bio-inspired optimizers were employed for hyperparameter tuning.The SSO-CatBoost hybrid achieved the lowest mean squared error and highest correlation coefficients,outperforming other metaheuristic approaches such as Genetic Algorithm,Particle Swarm Optimization,and Grey Wolf Optimizer.Statistical significance was established through Analysis of Variance and Wilcoxon signed-rank testing,confirming the robustness of the optimized models.The proposed methodology not only delivers improved predictive performance but also offers a transparent framework for mix design optimization,supporting data-driven decision making in sustainable and resilient infrastructure development.展开更多
Crushing waste coral concrete into recycled aggregates to create recycled coral aggregate concrete(RCAC)contributes to sustainable construction development on offshore islands and reefs.To investigate the impact of re...Crushing waste coral concrete into recycled aggregates to create recycled coral aggregate concrete(RCAC)contributes to sustainable construction development on offshore islands and reefs.To investigate the impact of recycled coral aggregate on concrete properties,this study performed a comprehensive analysis of the physical properties of recycled coral aggregate and the basic mechanical properties and microstructure of RCAC.The test results indicate that,compared to coral debris,the crushing index of recycled coral aggregate was reduced by 9.4%,while porosity decreased by 33.5%.Furthermore,RCAC retained the early strength characteristics of coral concrete,with compressive strength and flexural strength exhibiting a notable increase as the water-cement ratio decreased.Under identical conditions,the compressive strength and flexural strength of RCAC were 12.7% and 2.5% higher than coral concrete's,respectively,with porosity correspondingly reduced from 3.13% to 5.11%.This enhancement could be attributed to the new mortar filling the recycled coral aggregate.Scanning electron microscopy(SEM)analysis revealed three distinct interface transition zones within RCAC,with the‘new mortar-old mortar’interface identified as the weakest.The above findings provided a reference for the sustainable use of coral concrete in constructing offshore islands.展开更多
Conventional low-carbon concrete design approaches have often overlooked carbonation durability and the progressive loss of cover caused by surface scaling,both of which can increase the long-term risk of reinforcemen...Conventional low-carbon concrete design approaches have often overlooked carbonation durability and the progressive loss of cover caused by surface scaling,both of which can increase the long-term risk of reinforcement corrosion.To address these limitations,this study proposes an improved design framework for low-carbon slag concrete that simultaneously incorporates carbonation durability and cover scaling effects into the mix proportioning process.Based on experimental data,a linear predictive model was developed to estimate the 28-day compressive strength of slag concrete,achieving a correlation coefficient of R=0.87711 and a root mean square error(RMSE)of 7.55 MPa.The mechanism-based equation exhibits strong physical interpretability,as each parameter corresponds to a clear physical process,satisfying the requirements of design codes for physical significance.By integrating the strength and carbon-emission models,the carbon-emission efficiency was further analyzed.Across all water–binder ratios(0.3,0.4,0.5),CO_(2) emissions per unit strength decreased steadily with increasing slag content,indicating that carbon efficiency is primarily governed by slag replacement rather than the water/binder ratio.Four design cases,all with a design strength of 30 MPa,were then evaluated to illustrate the combined effects of carbonation and scaling.In Case 1,without considering carbonation durability,the carbonation depth after 50 years exceeded the 25 mm cover,leading to potential corrosion.In Case 2,when carbonation durability was considered,the required actual strength increased to 31.28 MPa.When mild cover scaling of 3 mm was introduced(Case 3),the required strength rose to 34.59 MPa,and under severe scaling of 10 mm(Case 4),it increased to 45.73 MPa.These results indicate that intensified scaling demands higher strength and lower water/binder ratios to maintain durability.Overall,the proposed framework quantitatively balances strength,durability,and embodied carbon,supporting sustainable low-carbon concrete design.展开更多
To study the durability of concrete in harsh environments in Northwest China,concrete was prepared with various durability-improving materials such as concrete anti-erosion inhibitor(SBT-TIA),acrylate polymer(AP),supe...To study the durability of concrete in harsh environments in Northwest China,concrete was prepared with various durability-improving materials such as concrete anti-erosion inhibitor(SBT-TIA),acrylate polymer(AP),super absorbent resin(SAP).The erosion mode and internal deterioration mechanism under salt freeze-thaw cycle and dry-wet cycle were explored.The results show that the addition of enhancing materials can effectively improve the resistance of concrete to salt freezing and sulfate erosion:the relevant indexes of concrete added with X-AP and T-AP are improved after salt freeze-thaw cycles;concrete added with SBTTIA shows optimal sulfate corrosion resistance;and concrete added with AP displays the best resistance to salt freezing.Microanalysis shows that the increase in the number of cycles decreases the generation of internal hydration products and defects in concrete mixed with enhancing materials and improves the related indexes.Based on the Wiener model analysis,the reliability of concrete with different lithologies and enhancing materials is improved,which may provide a reference for the application of manufactured sand concrete and enhancing materials in Northwest China,especially for the study of the improvement effects and mechanism of enhancing materials on the performance of concrete.展开更多
Unbonded post-tensioned(PT)concrete systems are widely used in safety-critical structures,yet model-ing practices for prestress implementation and tendon-concrete interaction remain inconsistent.This study investigate...Unbonded post-tensioned(PT)concrete systems are widely used in safety-critical structures,yet model-ing practices for prestress implementation and tendon-concrete interaction remain inconsistent.This study investigates the effects of sheath(duct)implementation and confinement assumptions through nonlinear finite element analysis.Four modeling cases were defined,consisting of an explicit sheath without tendon-concrete confinement(S)and three no-sheath variants with different confinement levels(X,N,A).One-way beams and two-way panels were analyzed,and panel blast responses were validated against experimental results.In both beams and panels,average initial stress levels were similar across models,through local stress concentrations appeared when the sheath was modeled.Under blast loading,these local effects became critical,and the sheath-implemented model reproduced experimental behavior most accurately,whereas non-implemented models deviated.Reduced blast intensity diminished the differences among models,thereby reaffirming that sheath-induced localization and damage propagation are critical factors.These findings highlight the importance of explicit sheath implementation for realistic numerical assessment of unbonded PT structures under extreme loads.展开更多
Many hydropower projects have been constructed in Southwest China with the strategic goal of achieving carbon neutrality.Most of these hydropower projects utilize concrete face rockfilldams(CFRDs)built on a deep overb...Many hydropower projects have been constructed in Southwest China with the strategic goal of achieving carbon neutrality.Most of these hydropower projects utilize concrete face rockfilldams(CFRDs)built on a deep overburden layer.The deep overburden layer causes uneven settlement between the overburden layer and the dam,which poses a serious threat to the safety of both the construction and operation of the dam.In this study,microseismic(MS)monitoring technology was employed for the firsttime in the fieldof dam fillingengineering,allowing for the real-time monitoring of microfracture in the bedrock during dam construction.The time-frequency analysis method was used to summarize the MS waveform characteristics induced by dam filling.The fracture mechanism of bedrock was revealed,and the relationships among slope deformation,dam settlement,and MS activity were analyzed.The following research results have been obtained.The MS signal induced by dam fillinghas low energy and amplitude,short duration,and high frequency.The fracture of the bedrock was mainly shear failure.MS monitoring can predict deformation during blasting excavation and capture the large settlement that may occur during dam fillingin advance.Research findingshave demonstrated the significantapplication value of MS monitoring technology in predicting the risk of dam settlement and provide a reference for similar projects.展开更多
We have described in detail the effects of nano-SiO_(2),nano-CaCO_(3),carbon nanotubes,and nano-Al_(2)O_(3) on geopolymer concrete from the perspectives of macro mechanics and microstructure.The existing research resu...We have described in detail the effects of nano-SiO_(2),nano-CaCO_(3),carbon nanotubes,and nano-Al_(2)O_(3) on geopolymer concrete from the perspectives of macro mechanics and microstructure.The existing research results show that the mechanism of nano-materials on geopolymer concrete mainly includes the filling effect,nucleation effect,and bridging effect,the appropriate amount of nano-materials can be used as fillers to reduce the porosity of geopolymer concrete,and can also react with Ca(OH)2 to produce C-S-H gel,thereby improving the mechanical properties of geopolymer concrete.The optimum content of nano-SiO_(2) is between 1.0%and 2.0%.The optimum content of nano-CaCO_(3) is between 2.0%and 3.0%.The optimum content of carbon nanotubes is between 0.1%and 0.2%.The optimum content of nano-Al_(2)O_(3) is between 1.0%and 2.0%.The main problems existing in the research and application of nanomaterial-modified geopolymer concrete are summarized,which lays a foundation for the further application of nanomaterial in geopolymer concrete.展开更多
基金Supported by Earmarked Fund for Modern Agro-industry Technology Research System(CARS-03)Special Fund for Seed Industry Construction from Taishan Scholar FoundationNational Science and Technology Major Project for Genetic Improvement of Crop Quality~~
文摘In this study, 13 strong-gluten wheat varieties screened by the Key Project of Modern Agricultural Industry Technology System ＂Study on Industrial Technology for Strong-gluten Wheat from Lime Concretion Black Soil Area in the Huanghuai Wheat Region＂ were used as experimental materials to investigate their bread-making quality, noodle-making quality and other related characteristics. The results showed that more than half of the wheat varieties had better bread-making quality; the bread made from wheat with longer dough mixing time than 3.0 min had better texture, lighter color, and better taste. All these 13 strong-gluten wheat varieties showed good noodle-making quality in color, appearance, smoothness and taste; the differences between varieties were mainly found in palatability and viscoelasticity. Jimai 20, Xinong 979, Zhengmai 7698, Ji＇nan 17 and Zhengmai 9023 exhibited excellent bread-making quality; Zhengmai 366, Jimai 20 and Xinong 979 displayed excellent noodle-making quality. Fresh dough sheets made from Zhengmai 366, Jimai 20 and Xinong 979 exhibited slight color variation within 24 h and high peak starch paste viscosity; dry and cooked noodles made from Zhengmai 366, Jimai 20 and Xinong 979 had good quality.
基金This work was supported by the National Natural Science Foundation of China(Program No.41330315)the Natural Science Foundation of Shaanxi Province(Program No.2020JQ-766)+1 种基金the Scientific Research Program Funded by Shaanxi Provincial Education Department(Program No.20JK0838)the Opening Foundation of Shandong Key Laboratory of Depositional Mineralization&Sedimentary Mineral,Shandong University of Science and Technology(Program No.DMSM20190034).
文摘Carbonate concretions are conspicuous in organic-rich shales and are generally related to decomposition of organic matter.The black shales from the Chang 7 Member of the Upper Triassic Yanchang Formation of the southern Ordos Basin host abundant carbonate concretions,which provide a unique record of depositional and early diagenetic conditions of the paleo-lake sediments.However,little attention has been given to the genesis and growth processes of the concretions in these lacustrine petroleum source rocks.New petrographic observations and geochemical analysis show that the concretions are composed of calcite,phosphate fossil fragments,K-NH4-feldspar,quartz,bitumen,and minor Fe-dolomite.Phosphate minerals,mainly carbonate fluorapatite(CFA),show pervasive replacement by calcite,most of which contains phosphorus,ranging in concentration from 0.26 to 2.35 wt%.This suggests that the phosphate minerals are the precursors for concretion growth.Positiveδ13C(+5.6 to+12.4‰V-PDB)signatures and the absence of pyrite indicate that microbial methanogenesis was the dominant driver for concretion growth,rather than bacterial sulfate reduction.Quartz,bitumen,and Fe-dolomite are the last cements that occurred,at deep burial depths and high temperatures.The formation of phosphate minerals might have been induced by upwelling of phosphate-enriched deep water in the Late Triassic paleo-lake,which promoted phytoplankton blooms and further enrichment of organic matter.Extremely slow sedimentation rates of fine-grained detrital minerals,relative to dead organism accumulation,led to the high permeabilities of the organic-rich sediments and rapid concretion growth during shallow burial.The close association of phosphate-bearing carbonate concretions and organic-rich shales reflects that upwelling played a critical role in the formation of the high-quality petroleum source rocks in the Triassic paleo-Ordos lake.
基金supported by the National Natural Science Foundation of China (No.42002148)the Program of Introducing Talents of Discipline to Universities (No.B14031)the Open Fund of the Key Laboratory of Tectonics and Petroleum Resources,Ministry of Education,China University of Geosciences (Nos.TPR-2021-10,TPR-2022-21)。
文摘The Early Cambrian Niutitang Formation is characterized by wide distribution of black shales on Yangtze Block,South China.Here we have reported the pyrite concretions in the bottom of the Niutitang Formation deposited in the slope-basin environment of Yangtze Block.The pyrite concretion was mainly composed of pyrite associated with hydrothermal minerals(barite,hyalophane,tetrahedrite),followed by quartz and organic matter.Trace elements Mo and U displayed significant enrichment(enrichment factors > 10),indicating the euxinic bottom water condition.Cu,Ni,and excess Ba concentrations were relatively high,denoting high primary productivity.In-situ sulfur isotope compositions of pyrite concretions δ34Spy) showed little variations(13.2‰–19.4‰) and small fractionations compared to coeval seawater δ34Sso4.Petrological and geochemical analyses indicated the pyrite concretions were formed in the sediment-water interface during the early diagenesis,with H2S diffusing from the euxinic water,and influenced by hydrothermal activity leading to the coexistence of barite,hyalophane,and tetrahedrite.These results imply euxinic bottom water featured by high primary productivity and increasing riverine flux of sulfate from chemical weathering during the Early Cambrian.
文摘Under the condition of thick alluvia, there is biggish declination in predicting the coal mining subsidence by commonly strip design method compared with the practical observation, the sinkage is much smaller. Based on the method of the probability integral about coal mining subsidence calculation, discussed the surface subsidence calculation and deduced the formulas caused by the clay with dewatering. The results show that the clay dewatering has great impact on surface subsidence. Therefore, the clay dewatering on surface subsidence should not be overlooked.
文摘To analyze the bacterial communities in lime concretion black soil upon the incorporation of crop residues for two years in wheat-maize system, total DNA was directly extracted and PCR-amplified with the F357GC and R518 primers targeting the 16S rRNA genes of V3 region. The amplified fragments were analyzed by perpendicular DGGE. Analyzing of species richness index S and Shannon diversity index H revealed that there was a high diversity of soil bacterial community compositions among all treatments after incorporation of crop residues and fertilizing under field conditions. Eleven DGGE bands recovered were re-amplified, sequenced. Phylogenetic analysis of the representative DGGE fingerprints identified four groups of the prokaryotic communities in the soil by returning wheat residues and fertilizing under field conditions. The bacterial communities belonged to gamma proteobacterium, Cupriavidus sp, halophilic eubacterium, Acidobacterium sp, Sorangium sp, delta proteobacterium, Streptococcus sp and Streptococcus agalactiae were main bacterial communities. Principal Component Analysis (PCA) showed that there were the differences in DNA profiles among the six treatments. It showed that wheat residue returning, maize residue returning and fertilizing all can improve bacterial diversity in varying degrees. As far as improvement of bacterial diversity was concerned, wheat residue returning was higher than fertilizing, and fertilizing higher than maize residue returning.
基金the National Natural Science Foundation of China (Grant Nos. 40572019 and 40621002)Prospective Study of China Petroleum and Chemical Corporation (Grant No. G0800-06-ZS-319)+1 种基金Ministry of Education of China (Grant No. NCET-04-0727, ‘the 111 Project’ B07011)National Science Foundation of USA (Grant No. EAR0745825)
文摘Mineralogical and textural characteristics and organic carbon composition of the carbonate concretions from the upper Doushantuo Formation (ca. 551 Ma) in the eastern Yangtze Gorge area reveal their early diagenetic (shallow) growth in organic-rich shale. High organic carbon content (up to 10%) and abundance of framboidal pyrites in the hosting shale suggest an anoxic or euxinic depositional environment. Well-preserved cardhouse clay fabrics in the concretions suggest their formation at 0-3 m burial depth, likely associated with microbial decomposition of organic matter and anaerobic oxidation of methane. Gases through decomposition of organic matter and/or from methanogenesis created bubbles and cavities, and anaerobic methane oxidation at the sulfate reduction zone resulted in carbonate precipitation, filling in bubbles and cavities to form spherical structures of the concretions. Rock pyrolysis analyses show that the carbonate concretions have lower total organic carbon (TOC) content but higher effective carbon than those in the host rocks. This may be caused by enclosed organic matter in pores of the concretions so that organic matter was protected from further modification during deep burial and maintained high hydrocarbon generating potential even in over-matured source rock. As a microbialite sensu latu, concretions have special growth conditions and may provide important information on the microbial activities in depositional and early burial environments.
基金supported by the National Natural Science Foundation of China (No. 41672336)the Fundamental Research Funds for the Central Universities (No. 2652018005 and 2652017050)
文摘Carbonate concretions provide unique records of ancient biogeochemical processes in marine sediments, and have the potential to reflect seawater chemistry indirectly. In fine-siliciclastic settings, they preferentially form in organicrich mudstones, owing to a significant fraction of the bicarbonate required for carbonate precipitation resulted from the decomposition of organic matter in sediments. In the Member IV of the Xiamaling Formation(ca. 1.40–1.35 Ga), North China, however, carbonate concretions occur in organic-poor green silty shales(avg. TOC = ~ 0.1 wt%).In order to elucidate the mechanism of the concretion formation and their environmental implications, a thorough study on the petrographic and geochemical compositions of the concretions and their host rocks was conducted.Macro-to microscopic fabrics, including deformed shale laminae surrounding the concretions, "cardhouse"structures of clay minerals and calcite geodes in the concretions, indicate that these concretions are of early diagenetic origin prior to the significant compaction of clay minerals. The carbon isotope compositions of the concretions(-1.7‰ to + 1.5‰) are stable and close to or slightly lower than that of the contemporaneous seawater, indicating that the bicarbonates required for the concretion formation were mainly sourced from seawater by diffusion rather than produced by methanogenesis or anoxic oxidation of methane(AOM); the rare occurrence of authigenic pyrite grains in the concretions likely indicates that bacterial sulfate reduction(BSR) did not play a significant role in their formation either. Almost all the calcite in the concretions has low Mn–Fe in nuclei but high Mn–Fe in rims with average Mn/Fe ratio close to 3.3. The calcite shows positive Ce anomalies(avg. 1.43)and low Y/Ho ratios(avg. 31). This evidence suggests that Mn reduction is the dominant process responsible for the formation of calcite rims while nitrate reduction probably triggered the precipitation of calcite nuclei.Prominence of Mn reduction in the porewater likely indicates that there was sufficient oxygen to support active Mn-redox cycling in the overlying seawater.
文摘In an attempt to provide more data about the mechanics of transition metal occurrence and translocation in soil environments, Fe-Mn concretions are separated from bulk samples of representative soil types and the element contents are determined. The results are reported and discussed in the sense of environmental geochemistry in this article.
基金Funded by the Science and Technology Program of Gansu Province(Nos.25JRRA497,23ZDFA017)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB0950000)High-level Talent Funding of Kashi。
文摘This study introduces superabsorbent polymers(SAP)into recycled concrete and,through freeze-thaw cycle tests,unconfined compressive strength tests,and nuclear magnetic resonance(NMR)analysis,evaluates the freeze-thaw resistance and durability of recycled concrete samples under varying freeze-thaw cycles.The results indicate that an appropriate addition of SAP significantly enhances the freeze-thaw resistance of recycled concrete.After 200 freeze-thaw cycles,the RS0.6 sample retained good surface integrity,demonstrating the best performance.Compared to NAC,its mass loss decreased by 1.16%,the relative dynamic modulus improved by 7.01%,and the compressive strength loss rate decreased by 5.41%.Additionally,T2 spectrum analysis revealed that adding SAP optimized the pore structure of recycled concrete and mitigated pore development during freeze-thaw cycles.As the number of freeze-thaw cycles increased,the RS0.3 and RS0.6 samples demonstrated superior frost resistance compared to NAC.However,an excessive amount of SAP increased pore expansion during subsequent freeze-thaw cycles,ultimately weakening frost resistance.
基金Funded by the Natural Science Foundation of Jiangsu Province(No.BK20220626)the National Natural Science Foundation of China(No.52078068)+2 种基金Science and Technology Innovation Foundation of NIT(No.KCTD006)Jiangsu Marine Structure Service Performance Improvement Engineering Research CenterKey Laboratory of Jiangsu"Marine Floating Wind Power Technology and Equipment"。
文摘We investigated the effects of fly ash(FA)content on the mechanical properties of recycled aggregate concrete(RAC)and its regeneration potential under freeze and thaw(F-T)cycles.The physical properties of second-generation recycled concrete aggregates(RCA)were used to analyze the regeneration potential of RAC after F-T cycles.Scanning electron microscopy was used to study the interfacial transition zone microstructure of RAC after F-T cycles.Results showed that adding 20%FA to RAC significantly enhanced its mechanical properties and frost resistance.Before the F-T cycles,the compressive strength of RAC with 20%FA reached 48.3 MPa,exceeding research strength target of 40 MPa.A majority of second-generation RCA with FA had been verified to attain class Ⅲ,which enabled their practical application in non-structural projects such as backfill trenches and road pavement.However,the second-generation RCA with 20%FA can achieve class Ⅱ,making it ideal for 40 MPa structural concrete.
基金Funded by the National Natural Science Foundation of China(No.52568032)Guangxi Key Research and Development Program(GKNos.AB24010020,AB23026071,and AD24010062)。
文摘The engineering application of low-alkali sulphoaluminate cement(L-SAC)is hindered due to the difficulty in adjusting the setting and hardening time.In this paper,lithium hydroxide and borax are mixed into L-SAC to regulate its setting and hardening process,so as to prepare a sulphoaluminate concrete material with high early strength and high fluidity.The effects of the ratio of lithium hydroxide to borax on the properties of L-SAC concrete were studied by hydration heat,XRD,TG-DTG,SEM and MIP.The experimental results show that the slump increases with the increase of borax content,and the early(3 h)strength increases with the increase of lithium hydroxide content.When 0.05% lithium hydroxide and 0.4% borax are added,the 0.5 h slump reaches 195 mm,and the 3 h compressive strength reaches 15.9 MPa.The increase of lithium hydroxide will promote the formation of early hydration products AFt and AH3 gel and accelerate the hydration process,while borax will inhibit the dissolution and hydration of cement and delay the setting and hardening process of concrete.The combination of the two ensures that the concrete has the characteristics of high early strength and high fluidity,and the early workability and mechanical properties can be controlled by the mix ratio.For long-term mechanical properties,the special concrete does not produce AFm,which can ensure the continuous development of strength.
基金Funded by the National Natural Science Foundation of China(Nos.52278518 and 51938011)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(No.24KJB560021)。
文摘Based on the split hopkinson pressure bar(SHPB)tests results,the cubic specimens have been numerically modeled in this paper to investigate the impact of key factors,such as the rise time,duration,and incident pulse shape,on achieving stress uniformity.After analysis,the paper provides actionable methods aimed at optimizing the conditions for stress uniformity within the cubic specimen.Finally,the lateral inertia effect of cubic specimen has been scrutinized to address the existing gap in this academic area.
文摘Accurate prediction of concrete compressive strength is fundamental for optimizing mix designs,improving material utilization,and ensuring structural safety in modern construction.Traditional empirical methods often fail to capture the non-linear relationships among concrete constituents,especially with the growing use of supple-mentary cementitious materials and recycled aggregates.This study presents an integrated machine learning framework for concrete strength prediction,combining advanced regression models—namely CatBoost—with metaheuristic optimization algorithms,with a particular focus on the Somersaulting Spider Optimizer(SSO).A comprehensive dataset encompassing diverse mix proportions and material types was used to evaluate baseline machine learning models,including CatBoost,XGBoost,ExtraTrees,and RandomForest.Among these,CatBoost demonstrated superior accuracy across multiple performance metrics.To further enhance predictive capability,several bio-inspired optimizers were employed for hyperparameter tuning.The SSO-CatBoost hybrid achieved the lowest mean squared error and highest correlation coefficients,outperforming other metaheuristic approaches such as Genetic Algorithm,Particle Swarm Optimization,and Grey Wolf Optimizer.Statistical significance was established through Analysis of Variance and Wilcoxon signed-rank testing,confirming the robustness of the optimized models.The proposed methodology not only delivers improved predictive performance but also offers a transparent framework for mix design optimization,supporting data-driven decision making in sustainable and resilient infrastructure development.
基金Funded by Natural Science Foundation of Guangxi(No.2025GXNSFBA069565)Guangxi Science and Technology Program(No.AD25069101)Guangxi Bagui Scholars Fund。
文摘Crushing waste coral concrete into recycled aggregates to create recycled coral aggregate concrete(RCAC)contributes to sustainable construction development on offshore islands and reefs.To investigate the impact of recycled coral aggregate on concrete properties,this study performed a comprehensive analysis of the physical properties of recycled coral aggregate and the basic mechanical properties and microstructure of RCAC.The test results indicate that,compared to coral debris,the crushing index of recycled coral aggregate was reduced by 9.4%,while porosity decreased by 33.5%.Furthermore,RCAC retained the early strength characteristics of coral concrete,with compressive strength and flexural strength exhibiting a notable increase as the water-cement ratio decreased.Under identical conditions,the compressive strength and flexural strength of RCAC were 12.7% and 2.5% higher than coral concrete's,respectively,with porosity correspondingly reduced from 3.13% to 5.11%.This enhancement could be attributed to the new mortar filling the recycled coral aggregate.Scanning electron microscopy(SEM)analysis revealed three distinct interface transition zones within RCAC,with the‘new mortar-old mortar’interface identified as the weakest.The above findings provided a reference for the sustainable use of coral concrete in constructing offshore islands.
基金supported by the National Natural Science Foundation of China(No.52463034)supported by the Korea Institute of Energy Technology Evaluation and Planning funded by the Ministry of Trade,Industry and Energy(No.2025-02314098)of the Republic of Koreasupported by the Regional Innovation System&Education(RISE)program through the Gangwon RISE Center,funded by the Ministry of Education(MOE)and the Gangwon State(G.S.),Republic of Korea(2025-RISE-10-002).
文摘Conventional low-carbon concrete design approaches have often overlooked carbonation durability and the progressive loss of cover caused by surface scaling,both of which can increase the long-term risk of reinforcement corrosion.To address these limitations,this study proposes an improved design framework for low-carbon slag concrete that simultaneously incorporates carbonation durability and cover scaling effects into the mix proportioning process.Based on experimental data,a linear predictive model was developed to estimate the 28-day compressive strength of slag concrete,achieving a correlation coefficient of R=0.87711 and a root mean square error(RMSE)of 7.55 MPa.The mechanism-based equation exhibits strong physical interpretability,as each parameter corresponds to a clear physical process,satisfying the requirements of design codes for physical significance.By integrating the strength and carbon-emission models,the carbon-emission efficiency was further analyzed.Across all water–binder ratios(0.3,0.4,0.5),CO_(2) emissions per unit strength decreased steadily with increasing slag content,indicating that carbon efficiency is primarily governed by slag replacement rather than the water/binder ratio.Four design cases,all with a design strength of 30 MPa,were then evaluated to illustrate the combined effects of carbonation and scaling.In Case 1,without considering carbonation durability,the carbonation depth after 50 years exceeded the 25 mm cover,leading to potential corrosion.In Case 2,when carbonation durability was considered,the required actual strength increased to 31.28 MPa.When mild cover scaling of 3 mm was introduced(Case 3),the required strength rose to 34.59 MPa,and under severe scaling of 10 mm(Case 4),it increased to 45.73 MPa.These results indicate that intensified scaling demands higher strength and lower water/binder ratios to maintain durability.Overall,the proposed framework quantitatively balances strength,durability,and embodied carbon,supporting sustainable low-carbon concrete design.
基金Funded by the National Natural Science Foundation of China(No.52178216)the Research on the Durability and Application of High-performance Concrete for Highway Engineering in the Cold and Arid Salt Areas of Northwest China(No.2022-24)the Construction Project of the Scientific Research Platform of Provincial Enterprises Supported by the Capital Operating Budget of Gansu Province(No.2023GZ018)。
文摘To study the durability of concrete in harsh environments in Northwest China,concrete was prepared with various durability-improving materials such as concrete anti-erosion inhibitor(SBT-TIA),acrylate polymer(AP),super absorbent resin(SAP).The erosion mode and internal deterioration mechanism under salt freeze-thaw cycle and dry-wet cycle were explored.The results show that the addition of enhancing materials can effectively improve the resistance of concrete to salt freezing and sulfate erosion:the relevant indexes of concrete added with X-AP and T-AP are improved after salt freeze-thaw cycles;concrete added with SBTTIA shows optimal sulfate corrosion resistance;and concrete added with AP displays the best resistance to salt freezing.Microanalysis shows that the increase in the number of cycles decreases the generation of internal hydration products and defects in concrete mixed with enhancing materials and improves the related indexes.Based on the Wiener model analysis,the reliability of concrete with different lithologies and enhancing materials is improved,which may provide a reference for the application of manufactured sand concrete and enhancing materials in Northwest China,especially for the study of the improvement effects and mechanism of enhancing materials on the performance of concrete.
基金supported by the Nuclear Safety Research Program through the Korea Foundation of Nuclear Safety(KoFONS)using the financial resource granted by the Nuclear Safety and Security Commission(NSSC)of the Republic of Korea[RS-2025-02310881]the Korea Institute of Energy Technology Evaluation and Planning[KETEP]grant funded by the Ministry of Trade,Industry and Energy(MOTIE)[RS-2025-25447272].
文摘Unbonded post-tensioned(PT)concrete systems are widely used in safety-critical structures,yet model-ing practices for prestress implementation and tendon-concrete interaction remain inconsistent.This study investigates the effects of sheath(duct)implementation and confinement assumptions through nonlinear finite element analysis.Four modeling cases were defined,consisting of an explicit sheath without tendon-concrete confinement(S)and three no-sheath variants with different confinement levels(X,N,A).One-way beams and two-way panels were analyzed,and panel blast responses were validated against experimental results.In both beams and panels,average initial stress levels were similar across models,through local stress concentrations appeared when the sheath was modeled.Under blast loading,these local effects became critical,and the sheath-implemented model reproduced experimental behavior most accurately,whereas non-implemented models deviated.Reduced blast intensity diminished the differences among models,thereby reaffirming that sheath-induced localization and damage propagation are critical factors.These findings highlight the importance of explicit sheath implementation for realistic numerical assessment of unbonded PT structures under extreme loads.
基金support from the Joint Funds of the National Natural Science Foundation of China(Grant No.42177143)the National Natural Science Foundation of China(Grant No.U23A2060).
文摘Many hydropower projects have been constructed in Southwest China with the strategic goal of achieving carbon neutrality.Most of these hydropower projects utilize concrete face rockfilldams(CFRDs)built on a deep overburden layer.The deep overburden layer causes uneven settlement between the overburden layer and the dam,which poses a serious threat to the safety of both the construction and operation of the dam.In this study,microseismic(MS)monitoring technology was employed for the firsttime in the fieldof dam fillingengineering,allowing for the real-time monitoring of microfracture in the bedrock during dam construction.The time-frequency analysis method was used to summarize the MS waveform characteristics induced by dam filling.The fracture mechanism of bedrock was revealed,and the relationships among slope deformation,dam settlement,and MS activity were analyzed.The following research results have been obtained.The MS signal induced by dam fillinghas low energy and amplitude,short duration,and high frequency.The fracture of the bedrock was mainly shear failure.MS monitoring can predict deformation during blasting excavation and capture the large settlement that may occur during dam fillingin advance.Research findingshave demonstrated the significantapplication value of MS monitoring technology in predicting the risk of dam settlement and provide a reference for similar projects.
基金Funded by the National Natural Science Foundation of China(Nos.U23A20672,52171270,51879168)the PI Project of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(GML20240001,GML2024009)。
文摘We have described in detail the effects of nano-SiO_(2),nano-CaCO_(3),carbon nanotubes,and nano-Al_(2)O_(3) on geopolymer concrete from the perspectives of macro mechanics and microstructure.The existing research results show that the mechanism of nano-materials on geopolymer concrete mainly includes the filling effect,nucleation effect,and bridging effect,the appropriate amount of nano-materials can be used as fillers to reduce the porosity of geopolymer concrete,and can also react with Ca(OH)2 to produce C-S-H gel,thereby improving the mechanical properties of geopolymer concrete.The optimum content of nano-SiO_(2) is between 1.0%and 2.0%.The optimum content of nano-CaCO_(3) is between 2.0%and 3.0%.The optimum content of carbon nanotubes is between 0.1%and 0.2%.The optimum content of nano-Al_(2)O_(3) is between 1.0%and 2.0%.The main problems existing in the research and application of nanomaterial-modified geopolymer concrete are summarized,which lays a foundation for the further application of nanomaterial in geopolymer concrete.
