Estimate of the Deterministic Neutron RBE for Radiation-induced Pseudo-Pelger Huët Cell Formation R.E.Goans1,2,C.J.Iddins1,R.E.Goans,Jr.3(1.Radiation Emergency Assistance Center/Training Site,Oak Ridge,TN;2.MJW C...Estimate of the Deterministic Neutron RBE for Radiation-induced Pseudo-Pelger Huët Cell Formation R.E.Goans1,2,C.J.Iddins1,R.E.Goans,Jr.3(1.Radiation Emergency Assistance Center/Training Site,Oak Ridge,TN;2.MJW Corporation,Amherst,NY;3.LMU Debusk School of Medicine,Harrogate,TN)Abstract:Using archival peripheral blood slides from radiation accident patients,we have recently described the pseudo-Pelger Huët anomaly(PPHA)in neutrophils as a new radiation-induced biomarker,useful for dosimetry not only immediately after a radiation incident but also potentially helpful as a tool in retrospective dosimetry.展开更多
Heterogeneous structure exhibits superiority in improving mechanical properties,whereas their effects on fatigue damage properties have rarely been studied.In this work,we employed a high-throughput gradient heat trea...Heterogeneous structure exhibits superiority in improving mechanical properties,whereas their effects on fatigue damage properties have rarely been studied.In this work,we employed a high-throughput gradient heat treatment method(757−857℃)to rapidly acquire the solution microstructure of the Ti-6554 alloy with different recrystallization degrees(0%,40%and 100%),followed by the same aging treatment.The results showed that theβ-hetero structure exhibited a yield strength(σ_(YS))of 1403 MPa,an increase of 6.7%,and a remarkable improvement in uniform elongation(UE)of 109.7%,reaching 6.5%,compared to the homogeneous structure.Interestingly,introducing a heterogeneous structure not only overcame the traditional trade-off between strength and ductility but also enhanced fatigue crack propagation(FCP)performance.During FCP process,β-hetero structure,through hetero-deformation induced(HDI)strengthening effects,promoted the accumulation of geometric necessary dislocations(GNDs)within coarseα_(S) phase,enabling faster attainment of the critical shear stress of twinning and increasing twinning density.This facilitated stress relief,improved plastic deformation in the crack tip zone,and increased the critical fast fracture threshold from 30.4 to 36.0 MPa·m^(1/2)showing an enlarged steady state propagation region.This study provides valuable insights on tailoring fatigue damage tolerance through heterogeneous structure for titanium alloys.展开更多
Perilla essential oil(PEO)is reported as an aromatic yellowish oily substance with a volatile odor extracted from perilla leaves.It exhibits various biological activities except anti-tobacco mosaic virus(TMV)activity....Perilla essential oil(PEO)is reported as an aromatic yellowish oily substance with a volatile odor extracted from perilla leaves.It exhibits various biological activities except anti-tobacco mosaic virus(TMV)activity.In this study,we investigated the main components and anti-TMV activity of PEO,identified its primary active components,and examined its mode of action.The results indicated that PEO exhibited anti-TMV activity(65.58%)at 800μg/mL,with perillaldehyde identified as the main active component.The protective,curative,and inactivation activities of perillaldehyde at 800μg/mL were 80.41%,73.42%,and 34.93%,respectively.These values were significantly higher than those of the control drug(commercial chitosan oligosaccharide)and the protective and curative activities were superior to those of ningnanmycin.The results of the mode of action showed that perillaldehyde induced a hypersensitive response(HR)in tobacco.Transmission electron microscope(TEM)observation revealed that perillaldehyde had no direct effect on TMV particles.The treatment of Nicotiana glutinosa with perillaldehyde at 800μg/mL indicated that perillaldehyde had significant induction activity(58.46%).The expression of three pathogenesis-related tobacco genes(PR genes),including nonexpressor of pathogenesis-related genes 1(NPR1),pathogenesis-related protein 1 gene(PR1),and pathogenesis-related protein 5 gene(PR5),were induced and upregulated by perillaldehyde treatment.Perillaldehyde also induced the overexpression of the phenylalanine ammonia-lyase gene(PAL),respiratory burst oxidase homolog B gene(RBOHB),and protochlorophyllide oxidoreductase gene 1(POR1).Furthermore,perillaldehyde increased the salicylic acid(SA)and H2O2 contents in tobacco leaves,and enhanced the activities of four defense enzymes:superoxide dismutase(SOD),catalase(CAT),peroxidase(POD),and phenylalanine ammonia-lyase(PAL).N.glutinosa was treated with perillaldehyde at 800μg/mL for 24 h,and the results showed that the highest SA and H_(2)O_(2) contents(1032.08 pmol/L and 23.40μmol/g FW,respectively)were obtained in tobacco leaves.Defense enzyme activities also reached a maximum at 800μg/mL,and the activities of CAT,PAL,POD,and SOD increased by 1.76,1.95,2.17,and 3.78 times,respectively,compared to the control.The results of the study showed that perillaldehyde may enhance resistance to pathogen infection by inducing systemic acquired resistance(SAR),which may contribute to the activation of SA signal transduction pathway.Therefore,perillaldehyde has the potential for application in agriculture as a novel antiviral agent and immune inducer.展开更多
Acetobacteraceae has garnered significant attention because of its unique properties and the broad applications of the bacterial cellulose it produces.However,unlike model strains,Acetobacteraceae have few synthetic b...Acetobacteraceae has garnered significant attention because of its unique properties and the broad applications of the bacterial cellulose it produces.However,unlike model strains,Acetobacteraceae have few synthetic biology applications because they are difficult to manipulate genetically and have insufficient genetic regulatory elements,among other factors.To address this limitation,this study characterized the fundamental properties and synthetic biology elements of three commonly used bacterial cellulose-producing strains.First,the basic characteristics of the three strains,including their cellulose film production ability,division time,antibiotic susceptibility,and plasmid features,were analyzed.Two inducible promoters(pTrc and pLux101)were subsequently characterized within the three strains.The inducibility of the pTrc promoter was relatively low across the three strains(induction ratio:1.98–6.39),whereas the pLux101 promoter demonstrated a significantly greater level of inducibility within the three strains(induction ratio:87.28–216.71).Finally,through gene knockout experiments,this study identified four genes essential for bacterial cellulose film production in the genome of the Gluconacetobacter hansenii ATCC 5358 strain.This study not only enriches the library of synthetic biology elements in nonmodel strains,but also lays the foundation for the synthetic biology applications of Acetobacteraceae.展开更多
Flame temperature and spectral emissivity were the important parameters characterizing the sufficient degree of fuel combustion and the particle radiative characteristics in the Rocket Based Combined Cycle(RBCC)combus...Flame temperature and spectral emissivity were the important parameters characterizing the sufficient degree of fuel combustion and the particle radiative characteristics in the Rocket Based Combined Cycle(RBCC)combustor.To investigate the combustion characteristics of the complex supersonic flame in the RBCC combustor,a new radiation thermometry combined with Levenberg-Marquardt(LM)algorithm and the least squares method was proposed to measure the temperature,emissivity and spectral radiative properties based on the flame emission spectrum.In-situ measurements of the flame temperature,emissivity and spectral radiative properties were carried out in the RBCC direct-connected test bench with laser-induced plasma combustion enhancement(LIPCE)and without LIPCE.The flame average temperatures at fuel global equivalence ratio(a)of 1.0b and 0.6 with LIPCE were 4.51%and 2.08%higher than those without LIPCE.The flame combustion oscillation of kerosene tended to be stable in the recirculation zone of cavity with the thermal and chemical effects of laser induced plasma.The differences of flame temperature at a=1.0b and 0.6 were 503 K and 523 K with LIPCE,which were 20.07%and42.64%lower than those without LIPCE.The flame emissivity with methane assisted ignition was 80.46%lower than that without methane assisted ignition,due to the carbon-hydrogen ratio of kerosene was higher than that of methane.The spectral emissivities at 600 nm with LIPCE were 1.25%,22.2%,and 4.22%lower than those without LIPCE at a=1.0a(with methane assisted ignition),1.0b(without methane assisted ignition)and 0.6.The effect of concentration in the emissivity was removed by normalization to analyze the flame radiative properties in the RBCC combustor chamber.The maximum differences of flame normalized emissivity were 50.91%without LIPCE and 27.53%with LIPCE.The flame radiative properties were stabilized under the thermal and chemical effects of laser induced plasma at a=0.6.展开更多
提出了一种基于频繁子树模式的GML文档结构聚类算法GCFS(GML Clustering based on Frequent Subtree patterns),与其他相关算法不同,该算法首先挖掘GML文档集合中的最大与闭合频繁Induced子树,并将其作为聚类特征,根据频繁子树的大小赋...提出了一种基于频繁子树模式的GML文档结构聚类算法GCFS(GML Clustering based on Frequent Subtree patterns),与其他相关算法不同,该算法首先挖掘GML文档集合中的最大与闭合频繁Induced子树,并将其作为聚类特征,根据频繁子树的大小赋予不同的权值,采用余弦函数定义相似度,利用K-Means算法对聚类特征进行聚类。实验结果表明算法GCFS是有效的,具有较高的聚类效率,性能优于其他同类算法。展开更多
Over the past 10 years adoptive immunotherapieshave been developed for cancer treatment. Cytotoxic Tlymphocytes (CTL) play a major role in host antitumorimmune response. The perforin and Fas ligand (Fas-L)pathways whi...Over the past 10 years adoptive immunotherapieshave been developed for cancer treatment. Cytotoxic Tlymphocytes (CTL) play a major role in host antitumorimmune response. The perforin and Fas ligand (Fas-L)pathways which were two major mechanisms are res-ponsible for tumor cell death by CTLs. A major obstacleto the application of adoptive imunotherapy in thetreatment of human malignancy has been the inability展开更多
Tumor cells escape host immune surveillance bydown-regulation of MHC and/or co-stimulatorymolecules.Anti-tumor immune responses are mediated primarily by T cells.A deficiency in either MHC or co-stimulatory molecules ...Tumor cells escape host immune surveillance bydown-regulation of MHC and/or co-stimulatorymolecules.Anti-tumor immune responses are mediated primarily by T cells.A deficiency in either MHC or co-stimulatory molecules on tumor cells is associated with a failure to induce anti-tumor immunity.展开更多
Dendritic cells (DC) play a critical role in theinduction of immune responses, and are utilized as potentadjuvants in cancer immunotherapy. Several strategies forloading DC with tumor antigens have been developed.Vacc...Dendritic cells (DC) play a critical role in theinduction of immune responses, and are utilized as potentadjuvants in cancer immunotherapy. Several strategies forloading DC with tumor antigens have been developed.Vaccination with tumor antigen-loaded DC wasdemonstrated to be capable of inducing antitumorimmunity, but some limitations still exist. So展开更多
Buried Si<sub>3</sub>N<sub>4</sub> layer is formed by hitrogen ion implanted silicoh with high energy （400Key） and high dose (1×10<sup>18</sup>/cm<sup>2</sup>). T...Buried Si<sub>3</sub>N<sub>4</sub> layer is formed by hitrogen ion implanted silicoh with high energy （400Key） and high dose (1×10<sup>18</sup>/cm<sup>2</sup>). The unimplanted single crystal zone is used as seed crystal. Seed inducing recrystallization is carried out by autoscanning Nd: YAG CW laser annealing. We got a large area SOI structure sample.展开更多
Wind erosion is a major cause of land desertification and sandstorm formation in arid and semi-arid areas.The objective of this study was to evaluate the potential of soybeans crude extract induced calcium carbonate p...Wind erosion is a major cause of land desertification and sandstorm formation in arid and semi-arid areas.The objective of this study was to evaluate the potential of soybeans crude extract induced calcium carbonate precipitation(SICP)on reducing wind erosion risk of sandy soil.Field tests were carried out in Ulan Buh Desert,Ningxia Hui Autonomous Region,China.Results showed that the SICP method could significantly enhance the surface strength and wind erosion resistance of the topsoil.The optimal cementation solution(urea-CaCl2)concentration and spraying volume,according to experiments conducted on sandy land,were 0.2 mol/L and 4 L/m^2,respectively.Under this condition,the CaCO3 content was approximately 0.45%,the surface strength of sandy soil could reach 306.2 kPa,and the depth of wind erosion was approximately zero,after 30 d completion of SICP treatment.Soil surface strength declined with the increase of time,and long-term sand fixation effects of SICP treatment varied depending on topography.Whereas wind erosion in the top area of the windward slope was remarkable,sandy soils on the bottom area of the windward slope still maintained a relatively high level of surface strength and a low degree of wind erosion 12 month after SICP treatment.Scanning electron microscopy(SEM)tests with energy dispersive X-ray(EDX)confirmed the precipitation of CaCO3 and its bridge effect.These findings suggested that the SICP method is a promising candidate to protect sandy soil from wind erosion in desert areas.展开更多
With the help of similar material simulation test,time series system for induced caving of roof in continuous mining under complex backfill in ore body No.92 of Tongkeng Tin Mine was studied. According to the similari...With the help of similar material simulation test,time series system for induced caving of roof in continuous mining under complex backfill in ore body No.92 of Tongkeng Tin Mine was studied. According to the similarity theory,a two-dimensional similar simulation test-bed was constructed. The stress and displacement that change along with the advance of mining were acquired and analyzed automatically by data system. The processes of continuous mining of ore-block in 5 intervals and artificial induced caving of roof were simulated. The results of the test show that ore body remained as safety roof in thickness of 15 m guarantees the safe advance of stoping work face. Caving of safety roof puts in practice at the first two mining intervals when the third interval of continuous mining is finished,and one interval as the safety distance should be kept all the time between stopping and caving. While mining in the last interval,pre-slotting should be implemented first of all,and the roof of the last two mining intervals is caved simultaneously. Only this kind of time series system can be an efficient and safe way for induced caving of roof in continuous mining.展开更多
In order to perfectly reflect the dynamic corrosion of reinforced concrete (RC) cover in practical engineering,an analytic model of non-uniform corrosion induced cracking was presented based on the elastic-plastic fra...In order to perfectly reflect the dynamic corrosion of reinforced concrete (RC) cover in practical engineering,an analytic model of non-uniform corrosion induced cracking was presented based on the elastic-plastic fracture mechanics theory.Comparisons with the published experimental data show that the predictions given by the present model are in good agreement with the results both for natural exposed experiments and short-time indoor tests (the best difference is about 2.7%).Also it obviously provides much better precision than those models under the assumption of uniform corrosion (the maximal improved precision is about 48%).Therefore,it is pointed out that the so-called uniform corrosion models to describe the cover cracking of RC should be adopted cautiously.Finally,the influences of thickness of local rusty layer around the reinforcing steel bar on the critical corrosion-induced crack indexes were investigated.It is found that the thickness of local rusty layer has great effect on the critical mass loss of reinforcing steel,threshold expansion pressure,and time to cover cracking.For local rusty layer thickness with a size of a=0.5 mm,the time to cover cracking will increase by about one times when a/b (a,semi-minor axis;b,semi-major axis) changes from 0.1 to 1 mm.展开更多
文摘Estimate of the Deterministic Neutron RBE for Radiation-induced Pseudo-Pelger Huët Cell Formation R.E.Goans1,2,C.J.Iddins1,R.E.Goans,Jr.3(1.Radiation Emergency Assistance Center/Training Site,Oak Ridge,TN;2.MJW Corporation,Amherst,NY;3.LMU Debusk School of Medicine,Harrogate,TN)Abstract:Using archival peripheral blood slides from radiation accident patients,we have recently described the pseudo-Pelger Huët anomaly(PPHA)in neutrophils as a new radiation-induced biomarker,useful for dosimetry not only immediately after a radiation incident but also potentially helpful as a tool in retrospective dosimetry.
基金Project(2021YFB3700801)supported by the National Key Research and Development Program of ChinaProject(2023JJ30683)supported by the Natural Science Foundation of Hunan Province,ChinaProject supported by the State Key Laboratory of Powder Metallurgy(Central South University),China。
文摘Heterogeneous structure exhibits superiority in improving mechanical properties,whereas their effects on fatigue damage properties have rarely been studied.In this work,we employed a high-throughput gradient heat treatment method(757−857℃)to rapidly acquire the solution microstructure of the Ti-6554 alloy with different recrystallization degrees(0%,40%and 100%),followed by the same aging treatment.The results showed that theβ-hetero structure exhibited a yield strength(σ_(YS))of 1403 MPa,an increase of 6.7%,and a remarkable improvement in uniform elongation(UE)of 109.7%,reaching 6.5%,compared to the homogeneous structure.Interestingly,introducing a heterogeneous structure not only overcame the traditional trade-off between strength and ductility but also enhanced fatigue crack propagation(FCP)performance.During FCP process,β-hetero structure,through hetero-deformation induced(HDI)strengthening effects,promoted the accumulation of geometric necessary dislocations(GNDs)within coarseα_(S) phase,enabling faster attainment of the critical shear stress of twinning and increasing twinning density.This facilitated stress relief,improved plastic deformation in the crack tip zone,and increased the critical fast fracture threshold from 30.4 to 36.0 MPa·m^(1/2)showing an enlarged steady state propagation region.This study provides valuable insights on tailoring fatigue damage tolerance through heterogeneous structure for titanium alloys.
基金Supported by National Natural Science Foundation of China(No.32072444)National Natural Science Foundation of China(No.32060429)the key Project of Natural Science Foundation of Xinjiang Uygur Autonomous Region(No.2022D01D44).
文摘Perilla essential oil(PEO)is reported as an aromatic yellowish oily substance with a volatile odor extracted from perilla leaves.It exhibits various biological activities except anti-tobacco mosaic virus(TMV)activity.In this study,we investigated the main components and anti-TMV activity of PEO,identified its primary active components,and examined its mode of action.The results indicated that PEO exhibited anti-TMV activity(65.58%)at 800μg/mL,with perillaldehyde identified as the main active component.The protective,curative,and inactivation activities of perillaldehyde at 800μg/mL were 80.41%,73.42%,and 34.93%,respectively.These values were significantly higher than those of the control drug(commercial chitosan oligosaccharide)and the protective and curative activities were superior to those of ningnanmycin.The results of the mode of action showed that perillaldehyde induced a hypersensitive response(HR)in tobacco.Transmission electron microscope(TEM)observation revealed that perillaldehyde had no direct effect on TMV particles.The treatment of Nicotiana glutinosa with perillaldehyde at 800μg/mL indicated that perillaldehyde had significant induction activity(58.46%).The expression of three pathogenesis-related tobacco genes(PR genes),including nonexpressor of pathogenesis-related genes 1(NPR1),pathogenesis-related protein 1 gene(PR1),and pathogenesis-related protein 5 gene(PR5),were induced and upregulated by perillaldehyde treatment.Perillaldehyde also induced the overexpression of the phenylalanine ammonia-lyase gene(PAL),respiratory burst oxidase homolog B gene(RBOHB),and protochlorophyllide oxidoreductase gene 1(POR1).Furthermore,perillaldehyde increased the salicylic acid(SA)and H2O2 contents in tobacco leaves,and enhanced the activities of four defense enzymes:superoxide dismutase(SOD),catalase(CAT),peroxidase(POD),and phenylalanine ammonia-lyase(PAL).N.glutinosa was treated with perillaldehyde at 800μg/mL for 24 h,and the results showed that the highest SA and H_(2)O_(2) contents(1032.08 pmol/L and 23.40μmol/g FW,respectively)were obtained in tobacco leaves.Defense enzyme activities also reached a maximum at 800μg/mL,and the activities of CAT,PAL,POD,and SOD increased by 1.76,1.95,2.17,and 3.78 times,respectively,compared to the control.The results of the study showed that perillaldehyde may enhance resistance to pathogen infection by inducing systemic acquired resistance(SAR),which may contribute to the activation of SA signal transduction pathway.Therefore,perillaldehyde has the potential for application in agriculture as a novel antiviral agent and immune inducer.
文摘Acetobacteraceae has garnered significant attention because of its unique properties and the broad applications of the bacterial cellulose it produces.However,unlike model strains,Acetobacteraceae have few synthetic biology applications because they are difficult to manipulate genetically and have insufficient genetic regulatory elements,among other factors.To address this limitation,this study characterized the fundamental properties and synthetic biology elements of three commonly used bacterial cellulose-producing strains.First,the basic characteristics of the three strains,including their cellulose film production ability,division time,antibiotic susceptibility,and plasmid features,were analyzed.Two inducible promoters(pTrc and pLux101)were subsequently characterized within the three strains.The inducibility of the pTrc promoter was relatively low across the three strains(induction ratio:1.98–6.39),whereas the pLux101 promoter demonstrated a significantly greater level of inducibility within the three strains(induction ratio:87.28–216.71).Finally,through gene knockout experiments,this study identified four genes essential for bacterial cellulose film production in the genome of the Gluconacetobacter hansenii ATCC 5358 strain.This study not only enriches the library of synthetic biology elements in nonmodel strains,but also lays the foundation for the synthetic biology applications of Acetobacteraceae.
基金supported by the National Natural Science Foundation of China (Grant Nos.52276185,52276189 and 51976057)the Fundamental Research Funds for the Central Universities (Grant No.2021MS126)+1 种基金the Natural Science Foundation of Jiangsu Province (Grant No.BK20231209)the Proof-of-Concept Project of Zhongguancun Open Laboratory (Grant No.20220981113)。
文摘Flame temperature and spectral emissivity were the important parameters characterizing the sufficient degree of fuel combustion and the particle radiative characteristics in the Rocket Based Combined Cycle(RBCC)combustor.To investigate the combustion characteristics of the complex supersonic flame in the RBCC combustor,a new radiation thermometry combined with Levenberg-Marquardt(LM)algorithm and the least squares method was proposed to measure the temperature,emissivity and spectral radiative properties based on the flame emission spectrum.In-situ measurements of the flame temperature,emissivity and spectral radiative properties were carried out in the RBCC direct-connected test bench with laser-induced plasma combustion enhancement(LIPCE)and without LIPCE.The flame average temperatures at fuel global equivalence ratio(a)of 1.0b and 0.6 with LIPCE were 4.51%and 2.08%higher than those without LIPCE.The flame combustion oscillation of kerosene tended to be stable in the recirculation zone of cavity with the thermal and chemical effects of laser induced plasma.The differences of flame temperature at a=1.0b and 0.6 were 503 K and 523 K with LIPCE,which were 20.07%and42.64%lower than those without LIPCE.The flame emissivity with methane assisted ignition was 80.46%lower than that without methane assisted ignition,due to the carbon-hydrogen ratio of kerosene was higher than that of methane.The spectral emissivities at 600 nm with LIPCE were 1.25%,22.2%,and 4.22%lower than those without LIPCE at a=1.0a(with methane assisted ignition),1.0b(without methane assisted ignition)and 0.6.The effect of concentration in the emissivity was removed by normalization to analyze the flame radiative properties in the RBCC combustor chamber.The maximum differences of flame normalized emissivity were 50.91%without LIPCE and 27.53%with LIPCE.The flame radiative properties were stabilized under the thermal and chemical effects of laser induced plasma at a=0.6.
文摘提出了一种基于频繁子树模式的GML文档结构聚类算法GCFS(GML Clustering based on Frequent Subtree patterns),与其他相关算法不同,该算法首先挖掘GML文档集合中的最大与闭合频繁Induced子树,并将其作为聚类特征,根据频繁子树的大小赋予不同的权值,采用余弦函数定义相似度,利用K-Means算法对聚类特征进行聚类。实验结果表明算法GCFS是有效的,具有较高的聚类效率,性能优于其他同类算法。
文摘Over the past 10 years adoptive immunotherapieshave been developed for cancer treatment. Cytotoxic Tlymphocytes (CTL) play a major role in host antitumorimmune response. The perforin and Fas ligand (Fas-L)pathways which were two major mechanisms are res-ponsible for tumor cell death by CTLs. A major obstacleto the application of adoptive imunotherapy in thetreatment of human malignancy has been the inability
文摘Tumor cells escape host immune surveillance bydown-regulation of MHC and/or co-stimulatorymolecules.Anti-tumor immune responses are mediated primarily by T cells.A deficiency in either MHC or co-stimulatory molecules on tumor cells is associated with a failure to induce anti-tumor immunity.
文摘Dendritic cells (DC) play a critical role in theinduction of immune responses, and are utilized as potentadjuvants in cancer immunotherapy. Several strategies forloading DC with tumor antigens have been developed.Vaccination with tumor antigen-loaded DC wasdemonstrated to be capable of inducing antitumorimmunity, but some limitations still exist. So
基金The project supported by National Natural Science Foundation of Chinapartly by USTC Foundation
文摘Buried Si<sub>3</sub>N<sub>4</sub> layer is formed by hitrogen ion implanted silicoh with high energy （400Key） and high dose (1×10<sup>18</sup>/cm<sup>2</sup>). The unimplanted single crystal zone is used as seed crystal. Seed inducing recrystallization is carried out by autoscanning Nd: YAG CW laser annealing. We got a large area SOI structure sample.
基金Projects(51978244,51979088,51608169)supported by the National Natural Science Foundation of China。
文摘Wind erosion is a major cause of land desertification and sandstorm formation in arid and semi-arid areas.The objective of this study was to evaluate the potential of soybeans crude extract induced calcium carbonate precipitation(SICP)on reducing wind erosion risk of sandy soil.Field tests were carried out in Ulan Buh Desert,Ningxia Hui Autonomous Region,China.Results showed that the SICP method could significantly enhance the surface strength and wind erosion resistance of the topsoil.The optimal cementation solution(urea-CaCl2)concentration and spraying volume,according to experiments conducted on sandy land,were 0.2 mol/L and 4 L/m^2,respectively.Under this condition,the CaCO3 content was approximately 0.45%,the surface strength of sandy soil could reach 306.2 kPa,and the depth of wind erosion was approximately zero,after 30 d completion of SICP treatment.Soil surface strength declined with the increase of time,and long-term sand fixation effects of SICP treatment varied depending on topography.Whereas wind erosion in the top area of the windward slope was remarkable,sandy soils on the bottom area of the windward slope still maintained a relatively high level of surface strength and a low degree of wind erosion 12 month after SICP treatment.Scanning electron microscopy(SEM)tests with energy dispersive X-ray(EDX)confirmed the precipitation of CaCO3 and its bridge effect.These findings suggested that the SICP method is a promising candidate to protect sandy soil from wind erosion in desert areas.
基金Project(50490274) supported by the National Natural Science Foundation of ChinaProject(20050533035) supported by the Specialized Research Fund for the Doctoral Program of Higher Education of ChinaProject(1343-77236) supported by the Doctor Degree Paper Innovation Engineering of Central South University, China
文摘With the help of similar material simulation test,time series system for induced caving of roof in continuous mining under complex backfill in ore body No.92 of Tongkeng Tin Mine was studied. According to the similarity theory,a two-dimensional similar simulation test-bed was constructed. The stress and displacement that change along with the advance of mining were acquired and analyzed automatically by data system. The processes of continuous mining of ore-block in 5 intervals and artificial induced caving of roof were simulated. The results of the test show that ore body remained as safety roof in thickness of 15 m guarantees the safe advance of stoping work face. Caving of safety roof puts in practice at the first two mining intervals when the third interval of continuous mining is finished,and one interval as the safety distance should be kept all the time between stopping and caving. While mining in the last interval,pre-slotting should be implemented first of all,and the roof of the last two mining intervals is caved simultaneously. Only this kind of time series system can be an efficient and safe way for induced caving of roof in continuous mining.
基金Project(50925829) supported by the National Science Fund for Distinguished Young Scholars of ChinaProject(50908148) supported by the National Natural Science Foundation of ChinaProjects(2009-K4-23,2010-11-33) supported by the Research of Ministry of Housing and Urban Rural Development of China
文摘In order to perfectly reflect the dynamic corrosion of reinforced concrete (RC) cover in practical engineering,an analytic model of non-uniform corrosion induced cracking was presented based on the elastic-plastic fracture mechanics theory.Comparisons with the published experimental data show that the predictions given by the present model are in good agreement with the results both for natural exposed experiments and short-time indoor tests (the best difference is about 2.7%).Also it obviously provides much better precision than those models under the assumption of uniform corrosion (the maximal improved precision is about 48%).Therefore,it is pointed out that the so-called uniform corrosion models to describe the cover cracking of RC should be adopted cautiously.Finally,the influences of thickness of local rusty layer around the reinforcing steel bar on the critical corrosion-induced crack indexes were investigated.It is found that the thickness of local rusty layer has great effect on the critical mass loss of reinforcing steel,threshold expansion pressure,and time to cover cracking.For local rusty layer thickness with a size of a=0.5 mm,the time to cover cracking will increase by about one times when a/b (a,semi-minor axis;b,semi-major axis) changes from 0.1 to 1 mm.
