BACKGROUND Transversus abdominis plane block(TAPB)is a block of the abdominal afferent nerve fibers between the internal oblique muscle and the transverse abdominal muscle achieved with local anesthetics.It can effect...BACKGROUND Transversus abdominis plane block(TAPB)is a block of the abdominal afferent nerve fibers between the internal oblique muscle and the transverse abdominal muscle achieved with local anesthetics.It can effectively block the conduction of the anterior nerve of the abdominal wall and exert a good analgesic effect.However,the effect of combining the block with remimazolam on anesthesia in patients undergoing gastrointestinal tumor surgery is still unclear.AIM To examine the effects of combining TAPB with remimazolam on the stress response and postoperative recovery of gastrointestinal tumor surgery patients.METHODS A retrospective analysis was conducted on the clinical data of 102 individuals diagnosed with gastrointestinal malignancies who underwent laparoscopic surgery under general anesthesia between April 2020 and June 2023.The patients were categorized into a control group(n=51),receiving remimazolam for general anesthesia,and an observation group(n=51),receiving TAPB combined with remimazolam for general anesthesia.A comparison was made between both groups in terms of hemodynamic parameters,stress markers,pain levels,recovery quality,analgesic effects,and adverse reactions during the perioperative period.RESULTS The observation group had significantly higher heart rates at time points 1 min after induction and upon leaving the operating room than the control group(P<0.05).The mean arterial pressure at time point T1 in the observation group was significantly higher than that in the control group(P<0.05).Five minutes after extubation,the levels of the hormones adrenaline and noradrenaline in the observation group were considerably lower than those in the control group(P<0.05).At 12 h,24 h,and 48 h following surgery,the visual analog scale scores of the observation group were considerably lower than those of the control group(P<0.05).The observation group had shorter awakening and extubation times and lower Riker sedation-agitation scale scores than the control group(P<0.05).The observation group exhibited considerably fewer effective pump presses,lower fentanyl dosages,and lower incidences of rescue analgesia within 24 h following surgery than the control group(P<0.05).CONCLUSION The application effect of TAPB combined with remimazolam general anesthesia in anesthesia of patients undergoing gastrointestinal tumor surgery is good,which is helpful to promote faster recovery after operation.展开更多
Microstructural development in hot working of TA15titanium alloy with primary stripαstructure was investigated withthe aim to globularizeαstrips.Results show that the mechanisms of morphology transformation are the ...Microstructural development in hot working of TA15titanium alloy with primary stripαstructure was investigated withthe aim to globularizeαstrips.Results show that the mechanisms of morphology transformation are the same to the spheroidizationmechanisms of lamellar structure.Boundary splitting and termination migration are more important than coarsening due to the largesize of stripα.Theαstrips are stable in annealing due to the unfavorable geometrical orientation of intra-αboundaries,the largethickness of strip and the geometrical stability ofαparticles.Predeformation and low speed deformation accelerate globularization ofαstrips in the following ways:direct changing of particle shape,promotion of boundary splitting and termination migration byincreasing high angle grain boundaries and interfacial area,promotion of coarsening by forming dislocation structures.Largepredeformation combined with high temperature annealing is a feasible way to globularize stripα.展开更多
To control the tri-modal microstructure and performance,a prediction model of tri-modal microstructure in the isothermal local loading forming of titanium alloy was developed.The staged isothermal local loading experi...To control the tri-modal microstructure and performance,a prediction model of tri-modal microstructure in the isothermal local loading forming of titanium alloy was developed.The staged isothermal local loading experiment on TA15alloy indicates that there exist four important microstructure evolution phenomena in the development of tri-modal microstructure,i.e.,the generation of lamellarα,content variation of equiaxedα,spatial orientation change of lamellarαand globularization of lamellarα.Considering the laws of these microstructure phenomena,the microstructure model was established to correlate the parameters of tri-modal microstructure and processing conditions.Then,the developed microstructure model was integrated with finite element(FE)model to predict the tri-modal microstructure in the isothermal local loading forming.Its reliability and accuracy were verified by the microstructure observation at different locations of sample.Good agreements between the predicted and experimental results suggest that the developed microstructure model and its combination with FE model are effective in the prediction of tri-modal microstructure in the isothermal local loading forming of TA15alloy.展开更多
To study deformation banding inβworking of TA15titanium alloy,hot simulation compression experiments were carried out on a Gleeble3500thermal simulator,and the microstructure was investigated by optical microscopy(OM...To study deformation banding inβworking of TA15titanium alloy,hot simulation compression experiments were carried out on a Gleeble3500thermal simulator,and the microstructure was investigated by optical microscopy(OM)and electron backscattered diffraction(EBSD).It is found that inβworking of TA15titanium alloy,deformation banding is still an important grain refinement mechanism up to temperature as high as0.7Tm(Tm is the melting temperature).Boundaries of deformation bands(DBBs)may be sharp or diffusive.Sharp DBBs retard discontinuous dynamic recrystallization(DDRX)by prohibiting nucleation,while the diffusive ones are sources of continuous dynamic recrystallization(CDRX).Deformation banding is more significant at high strain rate and large initial grain size.The average width of grain subdivisions is sensitive to strain rate but less affected by temperature and initial grain size.Multi-directional forging which produces crossing DDBs is potential to refine microstructure of small-size forgings.展开更多
Objective:To explore the clinical diagnostic value of combined detection of different tumor markers for primary hepatic carcinoma, and to provide the reference for the clinical diagnosis. Methods: 72 patients who were...Objective:To explore the clinical diagnostic value of combined detection of different tumor markers for primary hepatic carcinoma, and to provide the reference for the clinical diagnosis. Methods: 72 patients who were diagnosed with primary hepatic carcinoma were collected as observation group, 65 patients with benign liver disease as benign liver disease group and 80 cases of health examination as healthy control group, the contents of tumor markers alpha fetoprotein(AFP), carcinoembryonic antigen(CEA), carbohydrate antigen-199(CA199), carbohydrate antigen-125(CA125) and carbohydrate antigen-153(CA153) were determined by electrochemiluminescence in all subjects, then the results of five kinds of tumor markers and the positive rates of each index between the two groups were compared, the diagnostic value of separate and combined detection of different tumor markers in primary hepatic carcinoma were analyzed.Results: The values of AFP, CA199 and CA153 in the observation group were higher than the benign liver disease group, the values of AFP, CEA, CA199, CA125 and CA153 in the observation group were higher than the control group, the values of CA199 and CA125 in the benign liver disease group were higher than the control group, the differences were statistically significant (P<0.05). The positive rates of AFP, CEA, CA199 and CA153 in the observation group were higher than the benign liver disease group, the positive rates of AFP, CEA, CA199 and CA125 in the observation group were higher than the control group, the positive rates of AFP, CEA, CA199 and CA125 in the benign liver disease group were higher than the control group, the differences were statistically significant (P<0.05). The sensitivity of combined detection of all indicators for primary hepatic carcinoma was 86.4%, specificity, correct index, misdiagnosis rate and missed diagnosis rate were 86.4%, 89.2%, 75.6%, 13.6% and 10.8% respectively, and the combined detection was higher than the correct index of each index.Conclusion: Combined detection of serum tumor markers AFP, CEA, CA199, CA125 and CA153 can improve the sensitivity and specificity of diagnosis of primary hepatic carcinoma, it has better diagnostic value for primary hepatic carcinoma.展开更多
The effects of Cr contents(0.3 and 1.0 wt.%)and isothermal holding temperatures(400,440,and 480℃)on the microstructure evolution and properties of complex phase steel with high formability(CH steel)were investigated ...The effects of Cr contents(0.3 and 1.0 wt.%)and isothermal holding temperatures(400,440,and 480℃)on the microstructure evolution and properties of complex phase steel with high formability(CH steel)were investigated using dilatometry,scanning electron microscopy,transmission electron microscopy(TEM),and X-ray diffraction.The results show that the microstructures of CH steel with 0.3 wt.%Cr are ferrite,granular bainite,martensite,and retained austenite,while no ferrite is observed in the microstructure of CH steel with 1.0 wt.%Cr in the same process.Cr promotes the precipitation of(Nb,Ti)C in the high-temperature austenite region through theoretical calculations and TEM observations.Cr retards the bainite transformation and refines the grain size of CH steel.Furthermore,as isothermal holding temperature increases from 400 to 480℃,the bainite and retained austenite fractions of two CH steels decrease,while the martensite fraction increases in the steels after final quenching.Consequently,the strength has an increasing tendency and the total elongation has a decreasing tendency with increasing isothermal temperature.展开更多
How to form high-quality transverse inner ribs through power spinning is a key issue for complicated integrated curved generatrix parts with transverse inner ribs. In this study, the forming characteristics and laws d...How to form high-quality transverse inner ribs through power spinning is a key issue for complicated integrated curved generatrix parts with transverse inner ribs. In this study, the forming characteristics and laws during the power spinning process were investigated using a finite element simulation based on the orthogonal design method. The results show that the transverse inner rib distributes homogeneously along the circumferential direction but inhomogeneously along the generatrix direction. Depressions occur easily in the middle zone of the rib (MZR). The roller nose radius is the most significant parameter of the MZR underfill degree. A larger roller nose radius is helpful to decrease the MZR underfill degree. Furthermore, the preformed billet thickness also plays a vital role in the underfill degree of the front zone of the rib and the back zone of the rib, as well as the depression degree of the outer surface of the rib. By combining the ribfilling characteristics and laws, the optimized forming process window for obtaining high-quality inner ribs was obtained by regression analysis, thus laying a basis for improving the forming quality of curved generatrix parts with transverse inner ribs in power spinning.展开更多
The quenching and partitioning steel is the representative of the third generation of advanced high-strength steel.The effect of quenching temperature on the microstructure and mechanical property of ferrite-containin...The quenching and partitioning steel is the representative of the third generation of advanced high-strength steel.The effect of quenching temperature on the microstructure and mechanical property of ferrite-containing quenching and partitioning steel was studied by intercritical annealing quenching and partitioning processes.When preparing a test steel with a tensile strength of 1300 MPa and total elongation of 19%,it is found that the actual optimum quenching temperature was lower than that calculated according to the constrained carbon equilibrium.The results indicate that the martensite start temperature of the austenite was overestimated when considering the diffusion of carbon only.Austenite grain size which is affected by low temperature and the existence of ferrite during intercritical annealing influenced the optimum quenching temperature.A scheme considering the diffusion of various alloying elements and austenite grain size was proposed and verified.Using this scheme,the optimum quenching temperature of intercritically annealed quenching and partitioning steel with complex microstructures was well predicted.展开更多
Accurate diagnosis of early infections caused by the viral pathogen is a major challenge because patients usually have nonspecific signs.The development of sensitive,reliable,robust,and rapid laboratory tools is still...Accurate diagnosis of early infections caused by the viral pathogen is a major challenge because patients usually have nonspecific signs.The development of sensitive,reliable,robust,and rapid laboratory tools is still in high demand.Herein,we developed an extremely sensitive and affordable plasmonic immunoassay for respiratory syncytial virus(RSV)detection with the naked eye based on gold nanoparticles(AuNPs)/graphene hybrids combined with metal enhancement solution.The limit of detection was found to be 1.7 fg/mL,which was 100 times higher than that of the AuNPs-based method.The ultrahigh sensitivity could be attributed to the large number of well-dispersed AuNPs deposited on the graphene surface,which had an extremely high relative surface area.Further signal amplification was achieved by catalytic enlargement of AuNPs with HAuCl_(4)-NH_(2)OH redox reaction.Moreover,the plasmonic immunoassay was successfully used to detect RSV in artificial serum samples,showing great potential in practical applications.展开更多
Warm rotary draw bending provides a feasible method to form the large-diameter thin-walled(LDTW)TC4 bent tubes, which are widely used in the pneumatic system of aircrafts. An accurate prediction of flow behavior of ...Warm rotary draw bending provides a feasible method to form the large-diameter thin-walled(LDTW)TC4 bent tubes, which are widely used in the pneumatic system of aircrafts. An accurate prediction of flow behavior of TC4 tubes considering the couple effects of temperature,strain rate and strain is critical for understanding the deformation behavior of metals and optimizing the processing parameters in warm rotary draw bending of TC4 tubes. In this study, isothermal compression tests of TC4 tube alloy were performed from 573 to 873 K with an interval of 100 K and strain rates of 0.001, 0.010 and0.100 s^(-1). The prediction of flow behavior was done using two constitutive models, namely modified Arrhenius model and artificial neural network(ANN) model. The predictions of these constitutive models were compared using statistical measures like correlation coefficient(R), average absolute relative error(AARE) and its variation with the deformation parameters(temperature, strain rate and strain). Analysis of statistical measures reveals that the two models show high predicted accuracy in terms of R and AARE. Comparatively speaking, the ANN model presents higher predicted accuracy than the modified Arrhenius model. In addition, the predicted accuracy of ANN model presents high stability at the whole deformation parameter ranges, whereas the predictability of the modified Arrhenius model has some fluctuation at different deformation conditions. It presents higher predicted accuracy at temperatures of 573-773 K, strain rates of 0.010-0.100 s^(-1)and strain of 0.04-0.32, while low accuracy at temperature of 873 K, strain rates of 0.001 s^(-1)and strain of 0.36-0.48.Thus, the application of modified Arrhenius model is limited by its relatively low predicted accuracy at some deformation conditions, while the ANN model presents very high predicted accuracy at all deformation conditions,which can be used to study the compression behavior of TC4 tube at the temperature range of 573-873 K and the strain rate of 0.001-0.100 s^(-1). It can provide guideline for the design of processing parameters in warm rotary draw bending of LDTW TC4 tubes.展开更多
Based on the chemical composition of traditional hot-stamped steel(e.g.,22MnB5 and 30MnB5),Nb and V microalloying elements are added into 30MnB5 steel to meet the requirements of ultra-high strength,excellent ductilit...Based on the chemical composition of traditional hot-stamped steel(e.g.,22MnB5 and 30MnB5),Nb and V microalloying elements are added into 30MnB5 steel to meet the requirements of ultra-high strength,excellent ductility and potent resistance to hydrogen embrittlement(HE)at the same time.The influence of hot-stamped steel on HE was studied by conducting a hydrogen permeation method and pre-charged hydrogen slow strain rate test.Meanwhile,the experimental steel microstructures and corresponding fracture surfaces are observed and analyzed to characterize HE behavior.The results show that a finer microstructure,a lower apparent diffusion coefficient of hydrogen and a smaller percentage of strength and plasticity reduction are obtained due to the addition of the vanadium element into hot-stamped steel.Compared to the V free experimental steel,the steel with 0.14 wt.% V has a large number of dispersive precipitates and more grain boundary areas,which makes hydrogen atoms dispersedly distribute.展开更多
In the present work, the coupled effects of initial structure and processing parameters on microstructure of a two-phase titanium alloy were investigated to predict the microstructural evolution in multiple hot workin...In the present work, the coupled effects of initial structure and processing parameters on microstructure of a two-phase titanium alloy were investigated to predict the microstructural evolution in multiple hot working. It is found that microstructure with different constituent phases can be obtained by regulating the initial structure and hot working conditions. The variation of deformation degree and cooling rate can change the morphology of the con- stituent phases, but do not alter the phase fraction. The phase transformation during heating and holding determi- nes the phase fraction for a certain initial structure. ^--at-~3 transformation occurs during heating and holding. [3 to ct transformation leads to a significant increase in content and size of lamellar ~. The ct to [3 transformation occurs simultaneously in equiaxed at and lamellar ct. The thickness of lamellar ~t increases with temperature, which is caused by the vanishing of fine a lamellae due to phase transformation and coarsening by termination migration. By assuming a quasi-equilibrium phase transformation in heating and holding, a modeling approach is proposed for predicting microstructural evolution. The three stages of phase transformation are modeled separately and combined to predict the variation of phase fraction with temperature. Model predictions agree well with the experimental results.展开更多
文摘BACKGROUND Transversus abdominis plane block(TAPB)is a block of the abdominal afferent nerve fibers between the internal oblique muscle and the transverse abdominal muscle achieved with local anesthetics.It can effectively block the conduction of the anterior nerve of the abdominal wall and exert a good analgesic effect.However,the effect of combining the block with remimazolam on anesthesia in patients undergoing gastrointestinal tumor surgery is still unclear.AIM To examine the effects of combining TAPB with remimazolam on the stress response and postoperative recovery of gastrointestinal tumor surgery patients.METHODS A retrospective analysis was conducted on the clinical data of 102 individuals diagnosed with gastrointestinal malignancies who underwent laparoscopic surgery under general anesthesia between April 2020 and June 2023.The patients were categorized into a control group(n=51),receiving remimazolam for general anesthesia,and an observation group(n=51),receiving TAPB combined with remimazolam for general anesthesia.A comparison was made between both groups in terms of hemodynamic parameters,stress markers,pain levels,recovery quality,analgesic effects,and adverse reactions during the perioperative period.RESULTS The observation group had significantly higher heart rates at time points 1 min after induction and upon leaving the operating room than the control group(P<0.05).The mean arterial pressure at time point T1 in the observation group was significantly higher than that in the control group(P<0.05).Five minutes after extubation,the levels of the hormones adrenaline and noradrenaline in the observation group were considerably lower than those in the control group(P<0.05).At 12 h,24 h,and 48 h following surgery,the visual analog scale scores of the observation group were considerably lower than those of the control group(P<0.05).The observation group had shorter awakening and extubation times and lower Riker sedation-agitation scale scores than the control group(P<0.05).The observation group exhibited considerably fewer effective pump presses,lower fentanyl dosages,and lower incidences of rescue analgesia within 24 h following surgery than the control group(P<0.05).CONCLUSION The application effect of TAPB combined with remimazolam general anesthesia in anesthesia of patients undergoing gastrointestinal tumor surgery is good,which is helpful to promote faster recovery after operation.
基金Projects(51205317,51575449) supported by the National Natural Science Foundation of ChinaProject(3102015AX004) supported by the Fundamental Research Funds for the Central Universities,ChinaProject(104-QP-2014) supported by the Research Fund of the State Key Laboratory of Solidification Processing,China
文摘Microstructural development in hot working of TA15titanium alloy with primary stripαstructure was investigated withthe aim to globularizeαstrips.Results show that the mechanisms of morphology transformation are the same to the spheroidizationmechanisms of lamellar structure.Boundary splitting and termination migration are more important than coarsening due to the largesize of stripα.Theαstrips are stable in annealing due to the unfavorable geometrical orientation of intra-αboundaries,the largethickness of strip and the geometrical stability ofαparticles.Predeformation and low speed deformation accelerate globularization ofαstrips in the following ways:direct changing of particle shape,promotion of boundary splitting and termination migration byincreasing high angle grain boundaries and interfacial area,promotion of coarsening by forming dislocation structures.Largepredeformation combined with high temperature annealing is a feasible way to globularize stripα.
基金Projects(51605388,51575449)supported by the National Natural Science Foundation of ChinaProject(B08040)supported by the "111" Project,China+1 种基金Project(131-QP-2015)supported by the Research Fund of the State Key Laboratory of Solidification Processing(NWPU),ChinaProject supported by the Open Research Fund of State Key Laboratory of Materials Processing and Die&Mould Technology,Huazhong University of Science and Technology,China
文摘To control the tri-modal microstructure and performance,a prediction model of tri-modal microstructure in the isothermal local loading forming of titanium alloy was developed.The staged isothermal local loading experiment on TA15alloy indicates that there exist four important microstructure evolution phenomena in the development of tri-modal microstructure,i.e.,the generation of lamellarα,content variation of equiaxedα,spatial orientation change of lamellarαand globularization of lamellarα.Considering the laws of these microstructure phenomena,the microstructure model was established to correlate the parameters of tri-modal microstructure and processing conditions.Then,the developed microstructure model was integrated with finite element(FE)model to predict the tri-modal microstructure in the isothermal local loading forming.Its reliability and accuracy were verified by the microstructure observation at different locations of sample.Good agreements between the predicted and experimental results suggest that the developed microstructure model and its combination with FE model are effective in the prediction of tri-modal microstructure in the isothermal local loading forming of TA15alloy.
基金Projects(51205317,51575449)supported by the National Natural Science Foundation of ChinaProject(50935007)supported by the National Natural Science Foundation of China for Key Program+1 种基金Project(3102015AX004)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(104-QP-2014)supported by the Research Fund of the State Key Laboratory of Solidification Processing,China
文摘To study deformation banding inβworking of TA15titanium alloy,hot simulation compression experiments were carried out on a Gleeble3500thermal simulator,and the microstructure was investigated by optical microscopy(OM)and electron backscattered diffraction(EBSD).It is found that inβworking of TA15titanium alloy,deformation banding is still an important grain refinement mechanism up to temperature as high as0.7Tm(Tm is the melting temperature).Boundaries of deformation bands(DBBs)may be sharp or diffusive.Sharp DBBs retard discontinuous dynamic recrystallization(DDRX)by prohibiting nucleation,while the diffusive ones are sources of continuous dynamic recrystallization(CDRX).Deformation banding is more significant at high strain rate and large initial grain size.The average width of grain subdivisions is sensitive to strain rate but less affected by temperature and initial grain size.Multi-directional forging which produces crossing DDBs is potential to refine microstructure of small-size forgings.
基金Projects Funded by the National Natural Science Foundation of China.Project No:81700537.
文摘Objective:To explore the clinical diagnostic value of combined detection of different tumor markers for primary hepatic carcinoma, and to provide the reference for the clinical diagnosis. Methods: 72 patients who were diagnosed with primary hepatic carcinoma were collected as observation group, 65 patients with benign liver disease as benign liver disease group and 80 cases of health examination as healthy control group, the contents of tumor markers alpha fetoprotein(AFP), carcinoembryonic antigen(CEA), carbohydrate antigen-199(CA199), carbohydrate antigen-125(CA125) and carbohydrate antigen-153(CA153) were determined by electrochemiluminescence in all subjects, then the results of five kinds of tumor markers and the positive rates of each index between the two groups were compared, the diagnostic value of separate and combined detection of different tumor markers in primary hepatic carcinoma were analyzed.Results: The values of AFP, CA199 and CA153 in the observation group were higher than the benign liver disease group, the values of AFP, CEA, CA199, CA125 and CA153 in the observation group were higher than the control group, the values of CA199 and CA125 in the benign liver disease group were higher than the control group, the differences were statistically significant (P<0.05). The positive rates of AFP, CEA, CA199 and CA153 in the observation group were higher than the benign liver disease group, the positive rates of AFP, CEA, CA199 and CA125 in the observation group were higher than the control group, the positive rates of AFP, CEA, CA199 and CA125 in the benign liver disease group were higher than the control group, the differences were statistically significant (P<0.05). The sensitivity of combined detection of all indicators for primary hepatic carcinoma was 86.4%, specificity, correct index, misdiagnosis rate and missed diagnosis rate were 86.4%, 89.2%, 75.6%, 13.6% and 10.8% respectively, and the combined detection was higher than the correct index of each index.Conclusion: Combined detection of serum tumor markers AFP, CEA, CA199, CA125 and CA153 can improve the sensitivity and specificity of diagnosis of primary hepatic carcinoma, it has better diagnostic value for primary hepatic carcinoma.
基金The authors gratefully acknowledge the support from the Key Research and Development Plan of Shandong Province(No.2019TSLH0103)the New Energy Automobile Material Production and Application Demonstration Platform Project(No.TC180A6MR-1)Guangxi Innovation-Driven Development Special Fund Project(No.AA18242012).
文摘The effects of Cr contents(0.3 and 1.0 wt.%)and isothermal holding temperatures(400,440,and 480℃)on the microstructure evolution and properties of complex phase steel with high formability(CH steel)were investigated using dilatometry,scanning electron microscopy,transmission electron microscopy(TEM),and X-ray diffraction.The results show that the microstructures of CH steel with 0.3 wt.%Cr are ferrite,granular bainite,martensite,and retained austenite,while no ferrite is observed in the microstructure of CH steel with 1.0 wt.%Cr in the same process.Cr promotes the precipitation of(Nb,Ti)C in the high-temperature austenite region through theoretical calculations and TEM observations.Cr retards the bainite transformation and refines the grain size of CH steel.Furthermore,as isothermal holding temperature increases from 400 to 480℃,the bainite and retained austenite fractions of two CH steels decrease,while the martensite fraction increases in the steels after final quenching.Consequently,the strength has an increasing tendency and the total elongation has a decreasing tendency with increasing isothermal temperature.
基金the National Science Fund for Distinguished Young Scholars of China (Grant No. 51625505)the Key Program Project of the Joint Fund of Astronomy and the National Natural Science Foundation of China (Grant No. U1537203)the Open Research Fund of State Key Laboratory of High Performance Complex Manufacturing, Central South University.
文摘How to form high-quality transverse inner ribs through power spinning is a key issue for complicated integrated curved generatrix parts with transverse inner ribs. In this study, the forming characteristics and laws during the power spinning process were investigated using a finite element simulation based on the orthogonal design method. The results show that the transverse inner rib distributes homogeneously along the circumferential direction but inhomogeneously along the generatrix direction. Depressions occur easily in the middle zone of the rib (MZR). The roller nose radius is the most significant parameter of the MZR underfill degree. A larger roller nose radius is helpful to decrease the MZR underfill degree. Furthermore, the preformed billet thickness also plays a vital role in the underfill degree of the front zone of the rib and the back zone of the rib, as well as the depression degree of the outer surface of the rib. By combining the ribfilling characteristics and laws, the optimized forming process window for obtaining high-quality inner ribs was obtained by regression analysis, thus laying a basis for improving the forming quality of curved generatrix parts with transverse inner ribs in power spinning.
基金The authors gratefully acknowledge the support of the National Key Research and Development Program of Thirteenth Five-Year Plan Period(Grant No.2017YFB0304400)Production and Application Demonstration Platform of New Energy Automotive Material(Grant No.TC180A6MR-1).
文摘The quenching and partitioning steel is the representative of the third generation of advanced high-strength steel.The effect of quenching temperature on the microstructure and mechanical property of ferrite-containing quenching and partitioning steel was studied by intercritical annealing quenching and partitioning processes.When preparing a test steel with a tensile strength of 1300 MPa and total elongation of 19%,it is found that the actual optimum quenching temperature was lower than that calculated according to the constrained carbon equilibrium.The results indicate that the martensite start temperature of the austenite was overestimated when considering the diffusion of carbon only.Austenite grain size which is affected by low temperature and the existence of ferrite during intercritical annealing influenced the optimum quenching temperature.A scheme considering the diffusion of various alloying elements and austenite grain size was proposed and verified.Using this scheme,the optimum quenching temperature of intercritically annealed quenching and partitioning steel with complex microstructures was well predicted.
基金financially supported by the National Natural Science Foundation of China(21605126)the Fund of Chongqing Research Program of Basic Research and Frontier Technology(cstc2017jcyjAX0091)the Fundamental Research Funds for the Central Universities(SWU118015)
文摘Accurate diagnosis of early infections caused by the viral pathogen is a major challenge because patients usually have nonspecific signs.The development of sensitive,reliable,robust,and rapid laboratory tools is still in high demand.Herein,we developed an extremely sensitive and affordable plasmonic immunoassay for respiratory syncytial virus(RSV)detection with the naked eye based on gold nanoparticles(AuNPs)/graphene hybrids combined with metal enhancement solution.The limit of detection was found to be 1.7 fg/mL,which was 100 times higher than that of the AuNPs-based method.The ultrahigh sensitivity could be attributed to the large number of well-dispersed AuNPs deposited on the graphene surface,which had an extremely high relative surface area.Further signal amplification was achieved by catalytic enlargement of AuNPs with HAuCl_(4)-NH_(2)OH redox reaction.Moreover,the plasmonic immunoassay was successfully used to detect RSV in artificial serum samples,showing great potential in practical applications.
基金financially supported by the National Natural Science Foundation of China(Nos.51275415 and50905144)the Natural Science Basic Research Plan in Shanxi Province(No.2011JQ6004)the Program of the Ministry of Education of China for Introducing Talents of Discipline to Universities(No.B08040)
文摘Warm rotary draw bending provides a feasible method to form the large-diameter thin-walled(LDTW)TC4 bent tubes, which are widely used in the pneumatic system of aircrafts. An accurate prediction of flow behavior of TC4 tubes considering the couple effects of temperature,strain rate and strain is critical for understanding the deformation behavior of metals and optimizing the processing parameters in warm rotary draw bending of TC4 tubes. In this study, isothermal compression tests of TC4 tube alloy were performed from 573 to 873 K with an interval of 100 K and strain rates of 0.001, 0.010 and0.100 s^(-1). The prediction of flow behavior was done using two constitutive models, namely modified Arrhenius model and artificial neural network(ANN) model. The predictions of these constitutive models were compared using statistical measures like correlation coefficient(R), average absolute relative error(AARE) and its variation with the deformation parameters(temperature, strain rate and strain). Analysis of statistical measures reveals that the two models show high predicted accuracy in terms of R and AARE. Comparatively speaking, the ANN model presents higher predicted accuracy than the modified Arrhenius model. In addition, the predicted accuracy of ANN model presents high stability at the whole deformation parameter ranges, whereas the predictability of the modified Arrhenius model has some fluctuation at different deformation conditions. It presents higher predicted accuracy at temperatures of 573-773 K, strain rates of 0.010-0.100 s^(-1)and strain of 0.04-0.32, while low accuracy at temperature of 873 K, strain rates of 0.001 s^(-1)and strain of 0.36-0.48.Thus, the application of modified Arrhenius model is limited by its relatively low predicted accuracy at some deformation conditions, while the ANN model presents very high predicted accuracy at all deformation conditions,which can be used to study the compression behavior of TC4 tube at the temperature range of 573-873 K and the strain rate of 0.001-0.100 s^(-1). It can provide guideline for the design of processing parameters in warm rotary draw bending of LDTW TC4 tubes.
基金the National Natural Science Foundation of China(Grant No.51574028)the Development Program of Thirteenth Five-year Plan Period(Grant No.2017 YFB0304400)for Grant and financial support.
文摘Based on the chemical composition of traditional hot-stamped steel(e.g.,22MnB5 and 30MnB5),Nb and V microalloying elements are added into 30MnB5 steel to meet the requirements of ultra-high strength,excellent ductility and potent resistance to hydrogen embrittlement(HE)at the same time.The influence of hot-stamped steel on HE was studied by conducting a hydrogen permeation method and pre-charged hydrogen slow strain rate test.Meanwhile,the experimental steel microstructures and corresponding fracture surfaces are observed and analyzed to characterize HE behavior.The results show that a finer microstructure,a lower apparent diffusion coefficient of hydrogen and a smaller percentage of strength and plasticity reduction are obtained due to the addition of the vanadium element into hot-stamped steel.Compared to the V free experimental steel,the steel with 0.14 wt.% V has a large number of dispersive precipitates and more grain boundary areas,which makes hydrogen atoms dispersedly distribute.
基金financially supported by the National Natural Science Foundation of China (No. 51575449)the 111 Project (B08040)the Research Fund of the State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, China (No. 104-QP-2014)
文摘In the present work, the coupled effects of initial structure and processing parameters on microstructure of a two-phase titanium alloy were investigated to predict the microstructural evolution in multiple hot working. It is found that microstructure with different constituent phases can be obtained by regulating the initial structure and hot working conditions. The variation of deformation degree and cooling rate can change the morphology of the con- stituent phases, but do not alter the phase fraction. The phase transformation during heating and holding determi- nes the phase fraction for a certain initial structure. ^--at-~3 transformation occurs during heating and holding. [3 to ct transformation leads to a significant increase in content and size of lamellar ~. The ct to [3 transformation occurs simultaneously in equiaxed at and lamellar ct. The thickness of lamellar ~t increases with temperature, which is caused by the vanishing of fine a lamellae due to phase transformation and coarsening by termination migration. By assuming a quasi-equilibrium phase transformation in heating and holding, a modeling approach is proposed for predicting microstructural evolution. The three stages of phase transformation are modeled separately and combined to predict the variation of phase fraction with temperature. Model predictions agree well with the experimental results.