Three-point head fixation was constructed to provide mechanical stability for single unit recording(SUR)on vestibular sensory system in living chinchilla previously.However,it is no more qualified to this work when th...Three-point head fixation was constructed to provide mechanical stability for single unit recording(SUR)on vestibular sensory system in living chinchilla previously.However,it is no more qualified to this work when the stimulation intensity becomes large because of frequent unit losing and neuron damage,which strongly implies that the mechanical stability has been broken during the stimulation.Here,we constructed a novel hea0 fixation(skull cap assistant head fixation)provided by skull cap on the basis of three-point head fixation in order to improve the mechanical stability for SUR under the stimulation with large magnitude.The large area bone connection is the feature and advantage of this improved method,which directly fixes the tested local nervous tissue and microelectrode in an intact stable system through skull cap except two ear bars and a tube face mask.Our data exhibited that skull cap assistant head fixation could significantly improve the success rate of neural response activity recording in the population of semicircular canal neurons under the stimulation with large intensity(amplitudd 00 deg/s).Based on the analysis of neural response activity and noise base-line during stimulation,our data further indicated that this method could significantly improve the mechanical stability for SUR during high-speed motion stimulation on vestibular system in living chinchilla.Skull cap assistant head fixation extends the application of SUR on vestibular neuron in linear response range and provides a solid foundation for electrophysiological research on vestibular sensory system in fhrther studies.展开更多
This study focuses on the microstructure and mechanical properties of the joints of Q235 mild steel,which was formed by the friction stir welding(FSW).The results indicated that,after the FSW,the heat-affected zone(HA...This study focuses on the microstructure and mechanical properties of the joints of Q235 mild steel,which was formed by the friction stir welding(FSW).The results indicated that,after the FSW,the heat-affected zone(HAZ)of the retreating side(HAZRS)and the HAZ of the advancing side(HAZAS)recovered under the influence of the heating cycle.The transformation of the phases in the thermo-mechanically affected zone(TMAZ)of the retreating side(TMAZRS),the stir zone(SZ)and the TMAZ of the advancing side(TMAZAS)generated the pearlite and acicular ferrite.The continuous dynamic recrystallization occurred in all the three zones,whereas the grains were refined.The SZ mainly consisted of D1,D2 and F shear textures,while the TMAZAS was made up of only the F shear texture.The fine-grained structure,pearlite and the acicular ferrite improved the hardness and tensile strength of the joint.Its ultimate tensile strength was 479 MPa,which was 1.3% higher than that of the base metal.However,the uniform elongation was 16%,which showed a decrease of 33%.The fracture was a ductile fracture with the appearance of dimples.Besides,the joints of the FSW showed an excellent bending performance.展开更多
A large-scale fine-grained Mg-Gd-Y-Zn-Zr alloy plate with high strength and ductility was successfully prepared by multi-pass friction stir processing(MFSP)technology in this work.The structure of grains and long peri...A large-scale fine-grained Mg-Gd-Y-Zn-Zr alloy plate with high strength and ductility was successfully prepared by multi-pass friction stir processing(MFSP)technology in this work.The structure of grains and long period stacking ordered(LPSO)phase were characterized,and the mechanical properties uniformity was investigated.Moreover,a quantitative relationship between the microstructure and tensile yield strength was established.The results showed that the grains in the processed zone(PZ)and interfacial zone(IZ)were refined from 50μm to 3μm and 4μm,respectively,and numerous original LPSO phases were broken.In IZ,some block-shaped 18R LPSO phases were transformed into needle-like 14H LPSO phases due to stacking faults and the short-range diffusion of solute atoms.The severe shear deformation in the form of kinetic energy caused profuse stacking fault to be generated and move rapidly,greatly increasing the transformation rate of LPSO phase.After MFSP,the ultimate tensile strength,yield strength and elongation to failure of the large-scale plate were 367 MPa,305 MPa and 18.0% respectively.Grain refinement and LPSO phase strengthening were the major strengthening mechanisms for the MFSP sample.In particularly,the strength of IZ was comparable to that of PZ because the strength contribution of the 14H LPSO phase offsets the lack of grain refinement strengthening in IZ.This result opposes the widely accepted notion that IZ is a weak region in MFSP-prepared large-scale fine-grained plate.展开更多
Background: DNA methylation plays a vital role in reproduction.Entire genome DNA methylation changes during the oestrous phase(ES) and dioestrous phase(DS) in the ovaries of Guanzhong dairy goats were investigated usi...Background: DNA methylation plays a vital role in reproduction.Entire genome DNA methylation changes during the oestrous phase(ES) and dioestrous phase(DS) in the ovaries of Guanzhong dairy goats were investigated using bisulphite sequencing to understand the molecular biological mechanisms of these goats' oestrous cycle.Results: We discovered distinct genome-wide DNA methylation patterns in ES and DS ovaries.A total of 26,910 differentially methylated regions were upregulated and 21,453 differentially methylated regions were downregulated in the ES samples compared with the DS samples(P-values ≤0.05 and fold change of methylation ratios ≥2).Differentially methylated region analysis showed hypomethylation in the gene body regions and hypermethylation in the joining region between upstream regions and gene bodies.The methylation ratios of the STAR,FGF2,FGF12,BMP5 and SMAD6 genes in the ES samples were lower than those of the DS samples(P-values≤0.05 and fold change of methylation ratios ≥2).Conversely,the methylation ratios of the EGFR,TGFBR2,IGF2 BP1 and MMD2 genes increased in the ES samples compared with the DS samples.In addition,223 differentially methylated genes were found in the GnRH signalling pathway(KO04912),ovarian steroidogenesis pathway(KO04913),oestrogen signalling pathway(KO04915),oxytocin signalling pathway(KO04921),insulin secretion pathway(KO04911) and MAPK signalling pathway(KO04010).Conclusions: This study is the first large-scale comparison of the high-resolution DNA methylation landscapes of oestrous and dioestrous ovaries from dairy goats.Previous studies and our investigations have shown that the NR5 A2,STAR,FGF2 and BMP5 genes might have potential application value in regulating caprine oestrus.展开更多
Friction stir processing(FSP)was used to modify the microstructure and improve the mechanical properties and corrosion resistance of an Mg-Al-Ca alloy.The results demonstrated that,after FSP,the grain size of the Mg-A...Friction stir processing(FSP)was used to modify the microstructure and improve the mechanical properties and corrosion resistance of an Mg-Al-Ca alloy.The results demonstrated that,after FSP,the grain size of the Mg-Al-Ca alloy was decreased from 13.3 to 6.7μm.Meanwhile,the Al_(8)Mn_(5) phase was broken and dispersed,and its amount was increased.The yield strength and ultimate tensile strength of the Mg-Al-Ca alloy were increased by 17.0%and 10.1%,respectively,due to the combination of fine grain,second phase,and orientation strengthening,while the elongation was slightly decreased.The immersion and electrochemical corrosion rates in 3.5 wt%NaCl solution decreased by 18.4%and 37.5%,respectively,which contributed to grain refinement.However,the stress corrosion cracking(SCC)resistance of the modified Mg-Al-Ca alloy decreased significantly,which was mainly due to the filiform corrosion induced by the Al_(8)Mn_(5) phase.SCC was mainly controlled by anodic dissolution,while the cathodic hydrogen evolution accelerated the SCC process.展开更多
Friction stir processing(FSP), as a new kind of severe plastic deformation technique, can refine and homogenize the microstructure of metallic material. In this study, the effect of FSP on the microstructure and mecha...Friction stir processing(FSP), as a new kind of severe plastic deformation technique, can refine and homogenize the microstructure of metallic material. In this study, the effect of FSP on the microstructure and mechanical properties of pure Zr was investigated using electron backscatter diffraction analysis, microhardness and room-temperature tensile testing. The fine-grained(FG) structure with an average grain size of ~ 5.3 μm was obtained in the processed zone, where the average microhardness was ~ 198 HV, 1.6 times higher than that of base metal. Furthermore, tensile property of FG pure Zr exhibited obvious anisotropy owing to strong texture. Both grain size and texture had a significant effect on strength and ductility of FG pure Zr. High yield strength(248 MPa) and ultimate tensile strength(483 MPa), as well as good uniform elongation(10%) were achieved, which demonstrated that FSP was an effective method to fabricate bulk FG pure Zr with high strength and good ductility.展开更多
文摘Three-point head fixation was constructed to provide mechanical stability for single unit recording(SUR)on vestibular sensory system in living chinchilla previously.However,it is no more qualified to this work when the stimulation intensity becomes large because of frequent unit losing and neuron damage,which strongly implies that the mechanical stability has been broken during the stimulation.Here,we constructed a novel hea0 fixation(skull cap assistant head fixation)provided by skull cap on the basis of three-point head fixation in order to improve the mechanical stability for SUR under the stimulation with large magnitude.The large area bone connection is the feature and advantage of this improved method,which directly fixes the tested local nervous tissue and microelectrode in an intact stable system through skull cap except two ear bars and a tube face mask.Our data exhibited that skull cap assistant head fixation could significantly improve the success rate of neural response activity recording in the population of semicircular canal neurons under the stimulation with large intensity(amplitudd 00 deg/s).Based on the analysis of neural response activity and noise base-line during stimulation,our data further indicated that this method could significantly improve the mechanical stability for SUR during high-speed motion stimulation on vestibular system in living chinchilla.Skull cap assistant head fixation extends the application of SUR on vestibular neuron in linear response range and provides a solid foundation for electrophysiological research on vestibular sensory system in fhrther studies.
基金supported by the National Natural Science Foundation of China(Nos.51974220,U1760201)the National Key Research and Development Program of China(No.Z20180407)+2 种基金the Natural Science Foundation of Shaanxi Province(No.2019JQ-111)the Key Industrial Research Program of Shaanxi Province,China(No.2017ZDXM-GY-037,2020ZDLGY13-06)the Xi’an Science and Technology Project(No.201805033YD11CG17(8))。
文摘This study focuses on the microstructure and mechanical properties of the joints of Q235 mild steel,which was formed by the friction stir welding(FSW).The results indicated that,after the FSW,the heat-affected zone(HAZ)of the retreating side(HAZRS)and the HAZ of the advancing side(HAZAS)recovered under the influence of the heating cycle.The transformation of the phases in the thermo-mechanically affected zone(TMAZ)of the retreating side(TMAZRS),the stir zone(SZ)and the TMAZ of the advancing side(TMAZAS)generated the pearlite and acicular ferrite.The continuous dynamic recrystallization occurred in all the three zones,whereas the grains were refined.The SZ mainly consisted of D1,D2 and F shear textures,while the TMAZAS was made up of only the F shear texture.The fine-grained structure,pearlite and the acicular ferrite improved the hardness and tensile strength of the joint.Its ultimate tensile strength was 479 MPa,which was 1.3% higher than that of the base metal.However,the uniform elongation was 16%,which showed a decrease of 33%.The fracture was a ductile fracture with the appearance of dimples.Besides,the joints of the FSW showed an excellent bending performance.
基金supported by the National Key Research and Development Program of China(2021YFB3501002)State Key Program of National Natural Science Foundation of China(5203405)+3 种基金National Natural Science Foundation of China(51974220,52104383)National Key Research and Development Program of China(2021YFB3700902)Key Research and Development Program of Shaanxi Province(2020ZDLGY13-06,2017ZDXM-GY-037)Shaanxi Province National Science Fund for Distinguished Young Scholars(2022JC-24)。
文摘A large-scale fine-grained Mg-Gd-Y-Zn-Zr alloy plate with high strength and ductility was successfully prepared by multi-pass friction stir processing(MFSP)technology in this work.The structure of grains and long period stacking ordered(LPSO)phase were characterized,and the mechanical properties uniformity was investigated.Moreover,a quantitative relationship between the microstructure and tensile yield strength was established.The results showed that the grains in the processed zone(PZ)and interfacial zone(IZ)were refined from 50μm to 3μm and 4μm,respectively,and numerous original LPSO phases were broken.In IZ,some block-shaped 18R LPSO phases were transformed into needle-like 14H LPSO phases due to stacking faults and the short-range diffusion of solute atoms.The severe shear deformation in the form of kinetic energy caused profuse stacking fault to be generated and move rapidly,greatly increasing the transformation rate of LPSO phase.After MFSP,the ultimate tensile strength,yield strength and elongation to failure of the large-scale plate were 367 MPa,305 MPa and 18.0% respectively.Grain refinement and LPSO phase strengthening were the major strengthening mechanisms for the MFSP sample.In particularly,the strength of IZ was comparable to that of PZ because the strength contribution of the 14H LPSO phase offsets the lack of grain refinement strengthening in IZ.This result opposes the widely accepted notion that IZ is a weak region in MFSP-prepared large-scale fine-grained plate.
基金supported by the National Natural Science Foundation of China(31601925)China postdoctoral science foundation(2016 T90954)
文摘Background: DNA methylation plays a vital role in reproduction.Entire genome DNA methylation changes during the oestrous phase(ES) and dioestrous phase(DS) in the ovaries of Guanzhong dairy goats were investigated using bisulphite sequencing to understand the molecular biological mechanisms of these goats' oestrous cycle.Results: We discovered distinct genome-wide DNA methylation patterns in ES and DS ovaries.A total of 26,910 differentially methylated regions were upregulated and 21,453 differentially methylated regions were downregulated in the ES samples compared with the DS samples(P-values ≤0.05 and fold change of methylation ratios ≥2).Differentially methylated region analysis showed hypomethylation in the gene body regions and hypermethylation in the joining region between upstream regions and gene bodies.The methylation ratios of the STAR,FGF2,FGF12,BMP5 and SMAD6 genes in the ES samples were lower than those of the DS samples(P-values≤0.05 and fold change of methylation ratios ≥2).Conversely,the methylation ratios of the EGFR,TGFBR2,IGF2 BP1 and MMD2 genes increased in the ES samples compared with the DS samples.In addition,223 differentially methylated genes were found in the GnRH signalling pathway(KO04912),ovarian steroidogenesis pathway(KO04913),oestrogen signalling pathway(KO04915),oxytocin signalling pathway(KO04921),insulin secretion pathway(KO04911) and MAPK signalling pathway(KO04010).Conclusions: This study is the first large-scale comparison of the high-resolution DNA methylation landscapes of oestrous and dioestrous ovaries from dairy goats.Previous studies and our investigations have shown that the NR5 A2,STAR,FGF2 and BMP5 genes might have potential application value in regulating caprine oestrus.
基金financially supported by the National Natural Science Foundation of China(Nos.52034005,U1760201,51974220)the National Key Research and Development Program of China(No.2017YFB0306202)+2 种基金the Key Research and Development Program of Shaanxi Province(No.2017ZDXM-GY-037)the Youth Innovation Team of Shaanxi Universities(2019-2022)the China Baowu Iron and Steel Group Co.Ltd with Mg-Al-Ca alloy materials。
文摘Friction stir processing(FSP)was used to modify the microstructure and improve the mechanical properties and corrosion resistance of an Mg-Al-Ca alloy.The results demonstrated that,after FSP,the grain size of the Mg-Al-Ca alloy was decreased from 13.3 to 6.7μm.Meanwhile,the Al_(8)Mn_(5) phase was broken and dispersed,and its amount was increased.The yield strength and ultimate tensile strength of the Mg-Al-Ca alloy were increased by 17.0%and 10.1%,respectively,due to the combination of fine grain,second phase,and orientation strengthening,while the elongation was slightly decreased.The immersion and electrochemical corrosion rates in 3.5 wt%NaCl solution decreased by 18.4%and 37.5%,respectively,which contributed to grain refinement.However,the stress corrosion cracking(SCC)resistance of the modified Mg-Al-Ca alloy decreased significantly,which was mainly due to the filiform corrosion induced by the Al_(8)Mn_(5) phase.SCC was mainly controlled by anodic dissolution,while the cathodic hydrogen evolution accelerated the SCC process.
基金sponsorship from the National Natural Science Foundation of China(Nos.U1760201,51404180,and 51574192)the National Key Research and Development Program of China(No.Z20180407)+1 种基金the Key Industrial Research Program of Shaanxi Province,China(No.2017ZDXMGY-037)the Youth Innovation Team of Shaanxi Universities(No.2019-2022).
文摘Friction stir processing(FSP), as a new kind of severe plastic deformation technique, can refine and homogenize the microstructure of metallic material. In this study, the effect of FSP on the microstructure and mechanical properties of pure Zr was investigated using electron backscatter diffraction analysis, microhardness and room-temperature tensile testing. The fine-grained(FG) structure with an average grain size of ~ 5.3 μm was obtained in the processed zone, where the average microhardness was ~ 198 HV, 1.6 times higher than that of base metal. Furthermore, tensile property of FG pure Zr exhibited obvious anisotropy owing to strong texture. Both grain size and texture had a significant effect on strength and ductility of FG pure Zr. High yield strength(248 MPa) and ultimate tensile strength(483 MPa), as well as good uniform elongation(10%) were achieved, which demonstrated that FSP was an effective method to fabricate bulk FG pure Zr with high strength and good ductility.
