Glycogen metabolism plays a key role in the development of hepatoellular carcinoma(HCC),but the function of glycogen metabolism genes in the tumor microenvironment(TME)is still to be elucidated.Single cell RNA-seq dat...Glycogen metabolism plays a key role in the development of hepatoellular carcinoma(HCC),but the function of glycogen metabolism genes in the tumor microenvironment(TME)is still to be elucidated.Single cell RNA-seq data were obtained from ten HCC tumor samples totaling 64,545 cells and 65 glycogen metabolism genes were analyzed bya nonnegative matrix factorization(NMF).The prognosis and immune response of new glycogen TME cell dusters were predicted by using HCC and immunotherapy cohorts from public databases.HOC single cell analysis was divided into fibroblasts,NT T cells,macrophages,endothelial clls,and B cells,which were separately divided into new cell clusters by glycogen metabolism gene annotation.Pseudo temporal trajectory analysis demonstrated the temporal differentiation trajectory of different glycogen subtype cell dusters.Cellular communication analysis revealed extensive interactions between endothelial cells with glycogen metabolizing TME cell.related subtypes and diferent glycogen subtype cell clusters.SCENIC analysis of transcription factors upstream of TME cell clusters with different glycogen metabolism.In addition,TME cell dusters of glycogen metabolism were found to be enriched in expression in CAF subtypes,CD8 depleted,M1,and M2 types.Bulk seq analysis showed the prognostic signifcance of glycogen metabolism.mediated TME cell dusters in HCC,while a significant immune response was found in the immunotherapy cohort in patients treated with immune checkpoint blockade(ICB),especially for CAFs,T cells,and macrophages In summary,our study reveals for the first time that glycogen metabolism mediates intercellular communication in the hepatocellular carcinoma microenvironment while elucidating the anti-tumor mechanisms and immune prognostic responses of different subtypes of cell dusters.展开更多
The fault-controlled Nibao Carlin-type gold deposit,together with the strata-bound Shuiyindong deposit,comprise a significant amount of the disseminated gold deposits in southwestern Guizhou Province,China.Five main t...The fault-controlled Nibao Carlin-type gold deposit,together with the strata-bound Shuiyindong deposit,comprise a significant amount of the disseminated gold deposits in southwestern Guizhou Province,China.Five main types and two sub-types of pyrite at the Nibao deposit(Py1a/Py1b,Py2,Py3,Py4,Py5)were distinguished based on detailed mineralogical work.Py1,Py2and Py3 are Au-poor,whereas Py4 and Py5 are Au-rich,corresponding to a sedimentary and hydrothermal origin,respectively.Through systematic in situ analyses of NanoSIMS sulfur isotopes,the framboid pyrite Py1a with negative δ^34S values(-53.3 to-14.9%)from the Nibao deposit were found to originate from bacterial sulfate reduction(BSR)processes in an open and sulfate-sufficient condition while the superheavy pyrite Py1b(73.7–114.8%)is probably due to the potential influence of closed-system Rayleigh fractionation or the lack of preservation of deepsea sediments.Data of Py2 and Py3 plot within the area of S isotope compositions from biogenic and abiogenic sulfate reduction.In view of few coeval magmatic rocks in the mining district,the near zero δ^34S values of the Au-rich pyrites(Py4 and Py5)may discount the potential involvement of magmatic but metamorphic or sedimentary origin.LA-ICP-MS and TEM work show that Au in ore-related pyrite is present as both nanoparticles and structurally bound.LA-ICP-MS analyses show that the Au-rich pyrite also contains higher As,Cu,Sb,Tl and S than other types of pyrite,which inferred a distal manifestation of deep hydrothermal mineralization systems.展开更多
Mercury mines in Guizhou province are the main base of mercury production and the most important resource base in China.The San-Dan mercury belt in Guizhou province contains a series of important mercury deposits.Howe...Mercury mines in Guizhou province are the main base of mercury production and the most important resource base in China.The San-Dan mercury belt in Guizhou province contains a series of important mercury deposits.However,the source of metallogenic materials and the properties of metallogenic fluid of these mercury deposits have long been a controversial issue.In this study,we used cathode luminescence techniques to distinguish different stages of dolomite and calcite,laser ablation inductively coupled plasma mass spectrometry to analyze the trace elements,and stable isotope mass spectrometry techniques to analyze C-O isotopes compositions of dolomite and calcite in the Sixiangchang mercury deposit in San-Dan mercury belt.We also measured the sulfur isotope composition of cinnabar.Our study showed that dolomite can be divided into two stages,the lumpy dolomite associated with cinnabar in Dol 1 stage and dolomite vein in Dol 2 stage,which is associated with Cal 2 stage calcite vein.With the progress of mineralization,A1,As,Mo,Sb,and Sr elements were gradually enriched in the ore-forming fluid.The rare earth element(REE)partition curve of Dol 1 stage dolomite showed a trend of light REE enrichment.Cal 2 stage calcite and Dol 2 stage dolomite exhibited a flat-type REE partition curve,and Dol 2 stage dolomite showed a strong negative anomaly for Eu.δ^13C of carbonate mineral variation ranges from-6.89 to-2.16‰,whileδ^18O variation ranges from 13.80 to 23.09‰,and theδ34S variation range of cinnabar is 16.51-24.28‰.Carbonate mineral trace elements and C-O isotopes compositions suggested that early ore-forming fluid was reduced,and late ore-forming fluid was oxidized.The oreforming fluid of the Sixiangchang mercury deposit is a mixture of deep crustal fluid and meteoric water in deep thermal circulation,and involved in the oxidation of organic matter.The cinnabarδ^34S results showed that sulfur mainly came from seawater sulfate with the participation of microbial reduction.Sulfur is sedimentary in origin and was derived mainly from the host-rock strata.展开更多
The azimuth resolution improvement problem is solved via a coherent combination of synthetic aperture radar (SAR) ima-ges with the quasi-non-overlapped Doppler bandwidth. Prior to the spectra combination, SAR images...The azimuth resolution improvement problem is solved via a coherent combination of synthetic aperture radar (SAR) ima-ges with the quasi-non-overlapped Doppler bandwidth. Prior to the spectra combination, SAR images should be coregistered, while phase biases induced by topography, atmospheric propagation delays and baseline measurement errors should be calibrated. However, the coregistration accuracy suffers from large Doppler decorrelation caused by the quasi-non-overlapped Doppler band-width. Furthermore, the method used to estimate phase biases from interferogram of azimuth prefiltered SAR image pairs wil fail when there is no overlapped spectrum. The fringe simulation and maximum sharpness optimization are adopted to deal with the problems. Accordingly, a novel algorithm to coherently synthesize SAR images is presented. The experiment with the Terra SAR X-band (TerraSAR-X) satel ite data validates the performance of the presented method.展开更多
The Fukushima nuclear accident in Japan on March 11,2011,produced large amounts of Cs-polluted soil which must be controlled to prevent the spread of hazardous Cs into the environment.In this paper,the effects of heat...The Fukushima nuclear accident in Japan on March 11,2011,produced large amounts of Cs-polluted soil which must be controlled to prevent the spread of hazardous Cs into the environment.In this paper,the effects of heat treatment on the structure and properties of Cs-containing glass-ceramics,as a simulated nuclear waste form,were systematically investigated.Cesium atoms are chemically bonded in the pollucite structure,and the amorphous phase further encapsulates the pollucite crystals in the glassceramics,thus providing an extra protective layer for the immobilized Cs.XRD analysis,Raman and FT-IR studies on the glass-ceramics synergistically indicated that the optimum crystallization temperature for pollucite is around 1000℃.The pollucite is predominantly the main crystalline phase with a narrow crystal size distribution between 0.5 and 2 mm.Standard leaching test results show that the leaching rate of Cs was very low(3.0×10^(-3) g/(m^(2)·d)).The study offers a practical method for immobilizing Cs in pollucite-base glass-ceramics.Moreover,the experimentally obtained data may provide some important references for converting Cs-polluted soil into pollucite-base glass-ceramics waste form.展开更多
Long noncoding RNAs(lncRNAs)modulate many aspects of biological and pathological processes.Recent studies have shown that host lncRNAs participate in the antiviral immune response,but functional lncRNAs in coxsackievi...Long noncoding RNAs(lncRNAs)modulate many aspects of biological and pathological processes.Recent studies have shown that host lncRNAs participate in the antiviral immune response,but functional lncRNAs in coxsackievirus B5(CVB5)infection remain unknown.Here,we identified a novel cytoplasmic lncRNA,LINC1392,which was highly inducible in CVB5 infected RD cells in a time-and dose-dependent manner,and also can be induced by the viral RNA and IFN-β.Further investigation showed that LINC1392 promoted several important interferon-stimulated genes(ISGs)expression,including IFIT1,IFIT2,and IFITM3 by activating MDA5,thereby inhibiting the replication of CVB5 in vitro.Mechanistically,LINC1392 bound to ELAV like RNA binding protein 1(ELAVL1)and blocked ELAVL1 interaction with MDA5.Functional study revealed that the 245–835 nt locus of LINC1392 exerted the antiviral effect and was also an important site for ELAVL1 binding.In mice,LINC1392 could inhibit CVB5 replication and alleviated the histopathological lesions of intestinal and brain tissues induced by viral infection.Our findings collectively reveal that the novel LINC1392 acts as a positive regulator in the IFN-I signaling pathway against CVB5 infection.Elucidating the underlying mechanisms on how lncRNA regulats the host innate immunity response towards CVB5 infection will lay the foundation for antiviral drug research.展开更多
Electron beam welding (EBW) was applied to a 10-mm-thick plate cut from Ti-6246 compressor disk. The microstructural characteristics, microhardness and room temperature tensile properties were investigated. Microstr...Electron beam welding (EBW) was applied to a 10-mm-thick plate cut from Ti-6246 compressor disk. The microstructural characteristics, microhardness and room temperature tensile properties were investigated. Microstructure observations indicated that there existed plenty of thin needle-like α platelets studding in the matrix of the columnar β grains in the as-welded fusion zone (FZ). Post-weld heat treat- ment (PWHT) led to the precipitation of small secondary α platelets in the β matrix in heat affected zone and FZ. The thickness and the density of α platelets increased as the temperature of PWHT increased from 545 to 645 C. The microhardness across the Ti-6246 EBWjoint exhibited a nonuniform distribution. The hardness increased with the decrease of distance to the weld center, and reached the maximum of 467 HV in FZ when PWHT was carried out at 595 C. All the weldments tested with tension were fractured at the base material (BM) and exhibited a ductile fracture mode. The major deformation barrier in BM was the platelet α/β interfaces, however, the major deformation barrier in FZ was found to be β grain boundaries and secondary α/β interfaces. The BM with thicker platelet α phases had lower strength than the other two zones in the joint, and the BM deformed first and led to fracture in this zone.展开更多
Flos Sophorae Immaturus (FSI) possessed potential xanthine oxidase (XO) inhibitory activity as a uric acid-lowing natural product.The present work identified and quantified the free and bound polyphenols of FSI by UPL...Flos Sophorae Immaturus (FSI) possessed potential xanthine oxidase (XO) inhibitory activity as a uric acid-lowing natural product.The present work identified and quantified the free and bound polyphenols of FSI by UPLC-QTOF-MS.Then determined the primary polyphenols with XO inhibitory effect and clarified their potential mechanisms by omission experiment,interaction assay,inhibition type,and fluorescence measurements.The results revealed that nine polyphenols were detected in the free polyphenol extract and ten polyphenols were detected in the bound polyphenol extract.Meanwhile,seven polyphenols were identified as XO inhibitors,including quercetin,kaempferol,isorhamnetin,rutin,hyperoside,protocatechuic acid,and quercitrin with the IC50 values of 0.03,0.11,0.07,5.62,11.48,22.13,and 367.82 mg/mL,but their inhibition stability was lower than 24 h.Although the content of quercetin (18.87 mg/g) was not the highest,it played a crucial role to the XO inhibitory effect of FSI.Furthermore,kaempferol and isorhamnetin alone revealed the sub-additive effect with quercetin,while the combination of other polyphenols with quercetin generated the interference or antagonism effects.Quercetin,isorhamnetin,and kaempferol were mixed-type and competitive inhibitors,which significantly quenched the fluorescence intensity of XO.Moreover,the binding processes of quercetin-XO,kaempferol-XO,and isorhamnetin-XO were spontaneous and endothermic,and the hydrophobic interaction was the key driving force.In general,quercetin,kaempferol,and isorhamnetin in FSI can be used as potential XO inhibitors.展开更多
The high temperature creep behavior of fusion zone (FZ) and of a near-alpha titanium alloy Ti-60 has been investigated. base metal (BM) of the electron beam weldments While the BM shows a fully transformed, coarse...The high temperature creep behavior of fusion zone (FZ) and of a near-alpha titanium alloy Ti-60 has been investigated. base metal (BM) of the electron beam weldments While the BM shows a fully transformed, coarse primary β grains with large colonies consisting of aligned α lamellar, the FZ exhibits thin martensitic α′ platelets in the columnar β grains. The creep results show that the steady state creep rates of FZ follow the power-law creep, with the stress exponents obtained in the range from 5.6 (550℃) to 5.9 (600℃), and corrected activation energies of 309-352 kJ/mol; the stress exponents of BM exhibit different values when the creep testing stress and temperature alternate. The values of 2.4-3.2 are obtained when the stresses are under 220 MPa or the temperature is 550℃, also an exponent of 6.6 is achieved at stresses above 220 MPa at 600℃. The corrected activation energies of BM corresponding to the stress exponents are 123-161 kJ/mol (n=2.4-3.2) and 344 kJ/mol (n=6.6). The creep mechanisms of FZ and BM have been discussed in light of the creep microstructures, activation energies and the stress exponents. The creep mechanisms of FZ is the diffusion controlled dislocation climb, the creep of BM is controlled by 'solute drag' creep and dislocation climb when the stress and temperature are different. Transmission electron microscopy (TEM) observations of the dislocation structures of crept specimens are presented to give some supports for the creep behavior of FZ and BM. In addition to the creep mechanism of dislocation movement, the interface sliding has been found to play an important role during creep of FZ.展开更多
Hexagonal boron nitride(h-BN) powders were introduced into carbon fiber preform by powder addition and subsequent combined with chemical vapor infiltration(CVI) for densification to prepare carbon fiber reinforced/car...Hexagonal boron nitride(h-BN) powders were introduced into carbon fiber preform by powder addition and subsequent combined with chemical vapor infiltration(CVI) for densification to prepare carbon fiber reinforced/carbon and boron nitride dual matrix composites(C/C-BN). Microstructures and mechanical properties of C/C composites with three different volume contents of h-BN powders were investigated in comparison to pure C/C composites. Results indicated that the introduction of h-BN powders into C/C composites significantly reduced the size of Py C and the anisotropy of thermal contraction in matrix,leading to a gradual disappearance of ring defects as the h-BN content increased. In addition, an enhanced interfacial bonding between fiber and matrix obtained due to higher-textured Py C and rougher fiber surface. Thereby, the flexural strengths and modulus of as-prepared composites decreased firstly and then increased, while the impact toughness presented a decreasing tendency as the content of BN powders increased. Furthermore, with the increasing of h-BN content, anisotropies of compressive properties were weakened, and the compressive strength of C/C-BN composites were always higher than that of pure C/C composit. However, when C/C composites modified by 13.5 vol% content of h-BN, excessive loose BN aggregates appeared in C/C-BN composites, leading to a relatively slight reduction of compressive strength.展开更多
基金Liuzhou City's Top Ten Hundred Talents Project,Liuzhou Science and Technology Project(Grant Nos.2021CBC0126 and 2021CBC0123)Guangxi Zhuang Autonomous Region Health and Family Planning Commission Projects(Z20210561,Z20210903)+1 种基金liuzhou Scienceand Technology Plan Projects(2021CBC0121,2021CBC0128).
文摘Glycogen metabolism plays a key role in the development of hepatoellular carcinoma(HCC),but the function of glycogen metabolism genes in the tumor microenvironment(TME)is still to be elucidated.Single cell RNA-seq data were obtained from ten HCC tumor samples totaling 64,545 cells and 65 glycogen metabolism genes were analyzed bya nonnegative matrix factorization(NMF).The prognosis and immune response of new glycogen TME cell dusters were predicted by using HCC and immunotherapy cohorts from public databases.HOC single cell analysis was divided into fibroblasts,NT T cells,macrophages,endothelial clls,and B cells,which were separately divided into new cell clusters by glycogen metabolism gene annotation.Pseudo temporal trajectory analysis demonstrated the temporal differentiation trajectory of different glycogen subtype cell dusters.Cellular communication analysis revealed extensive interactions between endothelial cells with glycogen metabolizing TME cell.related subtypes and diferent glycogen subtype cell clusters.SCENIC analysis of transcription factors upstream of TME cell clusters with different glycogen metabolism.In addition,TME cell dusters of glycogen metabolism were found to be enriched in expression in CAF subtypes,CD8 depleted,M1,and M2 types.Bulk seq analysis showed the prognostic signifcance of glycogen metabolism.mediated TME cell dusters in HCC,while a significant immune response was found in the immunotherapy cohort in patients treated with immune checkpoint blockade(ICB),especially for CAFs,T cells,and macrophages In summary,our study reveals for the first time that glycogen metabolism mediates intercellular communication in the hepatocellular carcinoma microenvironment while elucidating the anti-tumor mechanisms and immune prognostic responses of different subtypes of cell dusters.
基金funded by the National 973 Program of China (2014CB440906)
文摘The fault-controlled Nibao Carlin-type gold deposit,together with the strata-bound Shuiyindong deposit,comprise a significant amount of the disseminated gold deposits in southwestern Guizhou Province,China.Five main types and two sub-types of pyrite at the Nibao deposit(Py1a/Py1b,Py2,Py3,Py4,Py5)were distinguished based on detailed mineralogical work.Py1,Py2and Py3 are Au-poor,whereas Py4 and Py5 are Au-rich,corresponding to a sedimentary and hydrothermal origin,respectively.Through systematic in situ analyses of NanoSIMS sulfur isotopes,the framboid pyrite Py1a with negative δ^34S values(-53.3 to-14.9%)from the Nibao deposit were found to originate from bacterial sulfate reduction(BSR)processes in an open and sulfate-sufficient condition while the superheavy pyrite Py1b(73.7–114.8%)is probably due to the potential influence of closed-system Rayleigh fractionation or the lack of preservation of deepsea sediments.Data of Py2 and Py3 plot within the area of S isotope compositions from biogenic and abiogenic sulfate reduction.In view of few coeval magmatic rocks in the mining district,the near zero δ^34S values of the Au-rich pyrites(Py4 and Py5)may discount the potential involvement of magmatic but metamorphic or sedimentary origin.LA-ICP-MS and TEM work show that Au in ore-related pyrite is present as both nanoparticles and structurally bound.LA-ICP-MS analyses show that the Au-rich pyrite also contains higher As,Cu,Sb,Tl and S than other types of pyrite,which inferred a distal manifestation of deep hydrothermal mineralization systems.
基金funded by the National 973 Program of China (2014CB440906)the key project of the National Natural Science Foundation of China (41230316)
文摘Mercury mines in Guizhou province are the main base of mercury production and the most important resource base in China.The San-Dan mercury belt in Guizhou province contains a series of important mercury deposits.However,the source of metallogenic materials and the properties of metallogenic fluid of these mercury deposits have long been a controversial issue.In this study,we used cathode luminescence techniques to distinguish different stages of dolomite and calcite,laser ablation inductively coupled plasma mass spectrometry to analyze the trace elements,and stable isotope mass spectrometry techniques to analyze C-O isotopes compositions of dolomite and calcite in the Sixiangchang mercury deposit in San-Dan mercury belt.We also measured the sulfur isotope composition of cinnabar.Our study showed that dolomite can be divided into two stages,the lumpy dolomite associated with cinnabar in Dol 1 stage and dolomite vein in Dol 2 stage,which is associated with Cal 2 stage calcite vein.With the progress of mineralization,A1,As,Mo,Sb,and Sr elements were gradually enriched in the ore-forming fluid.The rare earth element(REE)partition curve of Dol 1 stage dolomite showed a trend of light REE enrichment.Cal 2 stage calcite and Dol 2 stage dolomite exhibited a flat-type REE partition curve,and Dol 2 stage dolomite showed a strong negative anomaly for Eu.δ^13C of carbonate mineral variation ranges from-6.89 to-2.16‰,whileδ^18O variation ranges from 13.80 to 23.09‰,and theδ34S variation range of cinnabar is 16.51-24.28‰.Carbonate mineral trace elements and C-O isotopes compositions suggested that early ore-forming fluid was reduced,and late ore-forming fluid was oxidized.The oreforming fluid of the Sixiangchang mercury deposit is a mixture of deep crustal fluid and meteoric water in deep thermal circulation,and involved in the oxidation of organic matter.The cinnabarδ^34S results showed that sulfur mainly came from seawater sulfate with the participation of microbial reduction.Sulfur is sedimentary in origin and was derived mainly from the host-rock strata.
基金supported by the National Natural Science Foundationof China(41001282)
文摘The azimuth resolution improvement problem is solved via a coherent combination of synthetic aperture radar (SAR) ima-ges with the quasi-non-overlapped Doppler bandwidth. Prior to the spectra combination, SAR images should be coregistered, while phase biases induced by topography, atmospheric propagation delays and baseline measurement errors should be calibrated. However, the coregistration accuracy suffers from large Doppler decorrelation caused by the quasi-non-overlapped Doppler band-width. Furthermore, the method used to estimate phase biases from interferogram of azimuth prefiltered SAR image pairs wil fail when there is no overlapped spectrum. The fringe simulation and maximum sharpness optimization are adopted to deal with the problems. Accordingly, a novel algorithm to coherently synthesize SAR images is presented. The experiment with the Terra SAR X-band (TerraSAR-X) satel ite data validates the performance of the presented method.
基金The work was supported by the Anhui emphatic research and developmental projects(201904a05020079).
文摘The Fukushima nuclear accident in Japan on March 11,2011,produced large amounts of Cs-polluted soil which must be controlled to prevent the spread of hazardous Cs into the environment.In this paper,the effects of heat treatment on the structure and properties of Cs-containing glass-ceramics,as a simulated nuclear waste form,were systematically investigated.Cesium atoms are chemically bonded in the pollucite structure,and the amorphous phase further encapsulates the pollucite crystals in the glassceramics,thus providing an extra protective layer for the immobilized Cs.XRD analysis,Raman and FT-IR studies on the glass-ceramics synergistically indicated that the optimum crystallization temperature for pollucite is around 1000℃.The pollucite is predominantly the main crystalline phase with a narrow crystal size distribution between 0.5 and 2 mm.Standard leaching test results show that the leaching rate of Cs was very low(3.0×10^(-3) g/(m^(2)·d)).The study offers a practical method for immobilizing Cs in pollucite-base glass-ceramics.Moreover,the experimentally obtained data may provide some important references for converting Cs-polluted soil into pollucite-base glass-ceramics waste form.
基金This work was supported by the National Natural Science Foundation of China(No.81860357)the Young Talents Support Program of Yunnan Province,China(Ten Thousand People Plan,YNWR-QNBJ-2019-178).
文摘Long noncoding RNAs(lncRNAs)modulate many aspects of biological and pathological processes.Recent studies have shown that host lncRNAs participate in the antiviral immune response,but functional lncRNAs in coxsackievirus B5(CVB5)infection remain unknown.Here,we identified a novel cytoplasmic lncRNA,LINC1392,which was highly inducible in CVB5 infected RD cells in a time-and dose-dependent manner,and also can be induced by the viral RNA and IFN-β.Further investigation showed that LINC1392 promoted several important interferon-stimulated genes(ISGs)expression,including IFIT1,IFIT2,and IFITM3 by activating MDA5,thereby inhibiting the replication of CVB5 in vitro.Mechanistically,LINC1392 bound to ELAV like RNA binding protein 1(ELAVL1)and blocked ELAVL1 interaction with MDA5.Functional study revealed that the 245–835 nt locus of LINC1392 exerted the antiviral effect and was also an important site for ELAVL1 binding.In mice,LINC1392 could inhibit CVB5 replication and alleviated the histopathological lesions of intestinal and brain tissues induced by viral infection.Our findings collectively reveal that the novel LINC1392 acts as a positive regulator in the IFN-I signaling pathway against CVB5 infection.Elucidating the underlying mechanisms on how lncRNA regulats the host innate immunity response towards CVB5 infection will lay the foundation for antiviral drug research.
文摘Electron beam welding (EBW) was applied to a 10-mm-thick plate cut from Ti-6246 compressor disk. The microstructural characteristics, microhardness and room temperature tensile properties were investigated. Microstructure observations indicated that there existed plenty of thin needle-like α platelets studding in the matrix of the columnar β grains in the as-welded fusion zone (FZ). Post-weld heat treat- ment (PWHT) led to the precipitation of small secondary α platelets in the β matrix in heat affected zone and FZ. The thickness and the density of α platelets increased as the temperature of PWHT increased from 545 to 645 C. The microhardness across the Ti-6246 EBWjoint exhibited a nonuniform distribution. The hardness increased with the decrease of distance to the weld center, and reached the maximum of 467 HV in FZ when PWHT was carried out at 595 C. All the weldments tested with tension were fractured at the base material (BM) and exhibited a ductile fracture mode. The major deformation barrier in BM was the platelet α/β interfaces, however, the major deformation barrier in FZ was found to be β grain boundaries and secondary α/β interfaces. The BM with thicker platelet α phases had lower strength than the other two zones in the joint, and the BM deformed first and led to fracture in this zone.
基金subsidized by the Jiangsu Key R&D plan,China(BE2019309)Construction Project of Innovative Talents Base of Guizhou Province([2016]22)which has enabled us to accomplish this study.
文摘Flos Sophorae Immaturus (FSI) possessed potential xanthine oxidase (XO) inhibitory activity as a uric acid-lowing natural product.The present work identified and quantified the free and bound polyphenols of FSI by UPLC-QTOF-MS.Then determined the primary polyphenols with XO inhibitory effect and clarified their potential mechanisms by omission experiment,interaction assay,inhibition type,and fluorescence measurements.The results revealed that nine polyphenols were detected in the free polyphenol extract and ten polyphenols were detected in the bound polyphenol extract.Meanwhile,seven polyphenols were identified as XO inhibitors,including quercetin,kaempferol,isorhamnetin,rutin,hyperoside,protocatechuic acid,and quercitrin with the IC50 values of 0.03,0.11,0.07,5.62,11.48,22.13,and 367.82 mg/mL,but their inhibition stability was lower than 24 h.Although the content of quercetin (18.87 mg/g) was not the highest,it played a crucial role to the XO inhibitory effect of FSI.Furthermore,kaempferol and isorhamnetin alone revealed the sub-additive effect with quercetin,while the combination of other polyphenols with quercetin generated the interference or antagonism effects.Quercetin,isorhamnetin,and kaempferol were mixed-type and competitive inhibitors,which significantly quenched the fluorescence intensity of XO.Moreover,the binding processes of quercetin-XO,kaempferol-XO,and isorhamnetin-XO were spontaneous and endothermic,and the hydrophobic interaction was the key driving force.In general,quercetin,kaempferol,and isorhamnetin in FSI can be used as potential XO inhibitors.
文摘The high temperature creep behavior of fusion zone (FZ) and of a near-alpha titanium alloy Ti-60 has been investigated. base metal (BM) of the electron beam weldments While the BM shows a fully transformed, coarse primary β grains with large colonies consisting of aligned α lamellar, the FZ exhibits thin martensitic α′ platelets in the columnar β grains. The creep results show that the steady state creep rates of FZ follow the power-law creep, with the stress exponents obtained in the range from 5.6 (550℃) to 5.9 (600℃), and corrected activation energies of 309-352 kJ/mol; the stress exponents of BM exhibit different values when the creep testing stress and temperature alternate. The values of 2.4-3.2 are obtained when the stresses are under 220 MPa or the temperature is 550℃, also an exponent of 6.6 is achieved at stresses above 220 MPa at 600℃. The corrected activation energies of BM corresponding to the stress exponents are 123-161 kJ/mol (n=2.4-3.2) and 344 kJ/mol (n=6.6). The creep mechanisms of FZ and BM have been discussed in light of the creep microstructures, activation energies and the stress exponents. The creep mechanisms of FZ is the diffusion controlled dislocation climb, the creep of BM is controlled by 'solute drag' creep and dislocation climb when the stress and temperature are different. Transmission electron microscopy (TEM) observations of the dislocation structures of crept specimens are presented to give some supports for the creep behavior of FZ and BM. In addition to the creep mechanism of dislocation movement, the interface sliding has been found to play an important role during creep of FZ.
基金the financial supports from the Natural Science Foundation of Hunan Province (Grant No. 2019JJ50768)National Natural Science Foundation of China (Grant No. 51575536)+1 种基金the National High Technology Research and Development Program (Grant No. 2015AA033503)Graduate degree thesis Innovation Foundation of Central South University (Grant No. 2018ZZTS414)
文摘Hexagonal boron nitride(h-BN) powders were introduced into carbon fiber preform by powder addition and subsequent combined with chemical vapor infiltration(CVI) for densification to prepare carbon fiber reinforced/carbon and boron nitride dual matrix composites(C/C-BN). Microstructures and mechanical properties of C/C composites with three different volume contents of h-BN powders were investigated in comparison to pure C/C composites. Results indicated that the introduction of h-BN powders into C/C composites significantly reduced the size of Py C and the anisotropy of thermal contraction in matrix,leading to a gradual disappearance of ring defects as the h-BN content increased. In addition, an enhanced interfacial bonding between fiber and matrix obtained due to higher-textured Py C and rougher fiber surface. Thereby, the flexural strengths and modulus of as-prepared composites decreased firstly and then increased, while the impact toughness presented a decreasing tendency as the content of BN powders increased. Furthermore, with the increasing of h-BN content, anisotropies of compressive properties were weakened, and the compressive strength of C/C-BN composites were always higher than that of pure C/C composit. However, when C/C composites modified by 13.5 vol% content of h-BN, excessive loose BN aggregates appeared in C/C-BN composites, leading to a relatively slight reduction of compressive strength.