Hot deformation behavior and globularization mechanism of Ti6A14V0.1B alloy with lamellar micro structure were quantitatively studied through isothermal compression tests with the temperature range of 850950 ℃and str...Hot deformation behavior and globularization mechanism of Ti6A14V0.1B alloy with lamellar micro structure were quantitatively studied through isothermal compression tests with the temperature range of 850950 ℃and strain rate range of 0.011.00 s1. The results show that the peak flow stress and steady stress are sensitive to the strain rate and temperature. The value of deformation activation energy is 890.49 kJmo11 in (a+β) region. Dynamic recrystallization is the major deformation mecha nism. Flow softening is dominated by dynamic recrystallization at 850950 ℃. TiB particles promote the recrystallization of laths. Globularization processes consist of four steps: for mation of subgrain after dynamic recovery in a plates; subgrain boundary migration caused by interracial instability; interfacial migration promoting phase wedge into a phase; disintegrating of a laths by diffusion processes; and grain boundary sliding. Globularization mechanisms during hot deformation processes of the Ti6A14V0.1B alloy with lamellar structure are continuous dynamic recrystallization.展开更多
The solution for the forward displacement analysis(FDA) of the general 6-6 Stewart mechanism(i.e., the connection points of the moving and fixed platforms are not restricted to lying in a plane) has been extensive...The solution for the forward displacement analysis(FDA) of the general 6-6 Stewart mechanism(i.e., the connection points of the moving and fixed platforms are not restricted to lying in a plane) has been extensively studied, but the efficiency of the solution remains to be effectively addressed. To this end, an algebraic elimination method is proposed for the FDA of the general 6-6 Stewart mechanism. The kinematic constraint equations are built using conformal geometric algebra(CGA). The kinematic constraint equations are transformed by a substitution of variables into seven equations with seven unknown variables. According to the characteristic of anti-symmetric matrices, the aforementioned seven equations can be further transformed into seven equations with four unknown variables by a substitution of variables using the Grobner basis. Its elimination weight is increased through changing the degree of one variable, and sixteen equations with four unknown variables can be obtained using the Grobner basis. A 40th-degree univariate polynomial equation is derived by constructing a relatively small-sized 9 × 9 Sylvester resultant matrix. Finally, two numerical examples are employed to verify the proposed method. The results indicate that the proposed method can effectively improve the efficiency of solution and reduce the computational burden because of the small-sized resultant matrix.展开更多
The reaction mechanism of 2-methoxybenzaldehyde, 4-bromo-indanone, malononitrile and ammonium acetate one-pot to form 6-(2-methoxyphenyl)-2-amino-6-bromo-5 Hindeno[1,2-b]pyridine-3-carbonitrile was studied by densit...The reaction mechanism of 2-methoxybenzaldehyde, 4-bromo-indanone, malononitrile and ammonium acetate one-pot to form 6-(2-methoxyphenyl)-2-amino-6-bromo-5 Hindeno[1,2-b]pyridine-3-carbonitrile was studied by density functional theory. The geometries of the reactants, transition states, intermediates and products were optimized at the PW91/DNP level. Vibration analysis was carried out to confirm the transition state structure. Reaction pathways were investigated in this study. The result indicates that the reaction Re→ TSB1→IMB1→ TSB2→ IMB2→TSB3→IMB3→TSB4→IMB4→TSB5→IMB5→TSB6→IMB6→TSB7→IMB7→ TSB8→IMB8→TSB9→IMB9→P2 is the main pathway, the activation energy of which is the lowest. The dominant product predicted theoretically is in agreement with the experiment results.展开更多
The original Bacillus subtilis was isolated from the soil of an apple orchard,and B. subtilis strain BS80-6,selected from Bacillus subtilis by ion implantation,was used as an antagonist for postharvest biological cont...The original Bacillus subtilis was isolated from the soil of an apple orchard,and B. subtilis strain BS80-6,selected from Bacillus subtilis by ion implantation,was used as an antagonist for postharvest biological control against apple anthracnose( colletotrichum gloeosporioides). The mechanisms of action and efficacy of Bacillus subtilis strain BS80-6 against apple anthracnose caused by colletotrichum gloeosporioides were studied in vitro and on apples in controlled and semi-commercial conditions. An application of cell suspension( 108 cells per mL) of the antagonist in artificial wounds of apples reduced growth of C. gloeosporioides after storage at different temperatures. The inhibitory actions of cell culture to hyphal growth and to spores germination were 86. 6% and 98. 65%,respectively,and the control efficacy of cell culture against the disease was 60. 34% at room temperature. The results showed that BS80-6 was more effective against apple anthracnose.The cell culture of BS80-6 received better control efficacy against apple anthracnose than culture filtrates and autoclaved cell. All treatments significantly inhibited the disease both in vitro and in vivo compared with control. Fruits treated with cell culture and stored at 10 ℃ had lower infection rate,more delayed formation of acervwlus and smaller lesion diameter than those stored at 20 ℃. There was better control efficacy in fruits inoculated with spores after application of BS80-6. The mechanisms of BS80-6 activity appeared to involve production of an antifungal substance,deformation of hyphal cell and disintegration of cell wall. Besides,BS80-6 could improve the activity of major defense enzymes of apple,such as peroxidase( POD) and polyphenol oxidase( PPO).展开更多
The thermoelectric properties of Sr0.61Ba0.39Nb2O6-δ ceramics, reduced in different conditions, are investigated in the temperature range from 323 K to 1073 K. The electrical transport behaviors of the samples are do...The thermoelectric properties of Sr0.61Ba0.39Nb2O6-δ ceramics, reduced in different conditions, are investigated in the temperature range from 323 K to 1073 K. The electrical transport behaviors of the samples are dominated by the thermal-activated polaron hopping in the low temperature range, the Fermi glass behavior in the middle temperature range, and the Anderson localized behavior in the high temperature range. The thermal conductivity presents a plateau at high- temperatures, indicating a glass-like thermal conduction behavior. Both the thermoelectric power factor and the thermal conductivity increase with the increase of the degree of oxygen-reduction. Taking these two factors into account, the oxygen-reduction can still contribute to promoting the thermoelectric figure of merit. The highest ZT value is obtained to be -0.19 at 1073 K in the heaviest oxygen reduced sample.展开更多
The photochemical reaction of bicyclo[4.1.0]heptane was studied at the complete active space SCF(CASSCF) level with a 6-31G^* basis set. A muhireference MP2 algorithm that has been implemented in the Gaussian progr...The photochemical reaction of bicyclo[4.1.0]heptane was studied at the complete active space SCF(CASSCF) level with a 6-31G^* basis set. A muhireference MP2 algorithm that has been implemented in the Gaussian program was used to correct the energetics for the dynamic correlation. Starting from the Franck-Condon excitation of bicyclo [ 4.1.0 ] heptane, the reaction is via two bonds' breakage to give rise to 1,6-heptdiene. One internal conversion (IC) and two intersystem crossing points(ISC) were located and are discussed separately. The reaction proceeds to its own characteristic product on the ground state.展开更多
AIM: To compare three kinds of fluorescent probes for in vitro labeling and in vivo tracking of endothelial progenitor cells(EPCs) in a mouse model of laser-induced retinal injury.METHODS: EPCs were isolated from ...AIM: To compare three kinds of fluorescent probes for in vitro labeling and in vivo tracking of endothelial progenitor cells(EPCs) in a mouse model of laser-induced retinal injury.METHODS: EPCs were isolated from human umbilical cord blood mononuclear cells and labeled with three different fluorescent probes: 5-(and-6)-carboxyfluorescein diacetate succinimidyl ester(CFSE), 1,1′-dilinoleyl-3,3,3′,3′-tetramethylindo-carbocyanine perchlorate linked acetylated low-density lipoprotein(Di I-Ac LDL), and green fluorescent protein(GFP). The fluorescent intensity of EPCs was examined by confocal microscopy. Survival rate of labeled EPCs was calculated with trypan blue staining, and their adhesive capability was assessed. A mouse model of retinal injury was induced by laser, and EPCs were injected into the vitreous cavity. Frozen section and fluorescein angiography on flat-mounted retinal samples was employed to track the labeled EPCs in vivo.RESULTS: EPCs labeled with CFSE and Di I-Ac LDL exhibited an intense green and red fluorescence at the beginning; the fluorescence intensity decreased gradually to 20.23% and 49.99% respectively, after 28 d. On the contrary, the florescent intensity of GFP-labeled EPCs increased in a time-dependent manner. All labeled EPCs showed normal morphology and no significant change in survival and adhesive capability. In the mouse model, transplantation of EPCs showed a protective effect against retinal injury. EPCs labeled with CFSE and Di I-Ac LDL were successfully tracked in mice during the development of retinal injury and repair; however, GFP-labeled EPCs were not detected in the laser-injured mouse retina.CONCLUSION: The three fluorescent markers used in this study have their own set of advantages and disadvantages. CFSE and Di I-Ac LDL are suitable for short-term EPClabeling, while GFP should be used for long-term labeling. The choice of fluorescent markers should be guided by the purpose of the study.展开更多
The porous metallic biomaterials have attracted significant attention for implants because their lower young's modulus matches the human bones, which can eliminate the stress shielding effect and facilitate the gr...The porous metallic biomaterials have attracted significant attention for implants because their lower young's modulus matches the human bones, which can eliminate the stress shielding effect and facilitate the growth of bone tissue cells. The porous metallic biomaterials fabricated by selective laser melting (SLM) have broad prospects, but the surface of the SLM-built porous structure has been severely adhered with unmelted powders, which affects the forming accuracy and surface quality. The porous metallic biomaterials face the corrosion problem of complex body fluid environments during service, so their corrosion resistance in the human body is extremely important. The surface quality will affect the corrosion resistance of the porous metallic biomaterials. Therefore, it is necessary to study the effect of post-treatment on the corrosion resistance of SLMed samples. In this work, the mechanical response and the electrochemical corrosion behavior in simulated body fluid of diamond and pentamode metamaterials Ti-6Al-4V alloy fabricated by SLM before and after sandblasting were studied. After sandblasting, the mechanical properties of the two porous metallic biomaterials were slightly improved, and the self-corrosion potential and pitting potential were more negative;meanwhile, the self-corrosion current density and passive current density increased, indicating that its corrosion performance decreased, and the passive film stability of sandblasted samples got worse.展开更多
基金supported by the International Science and Technology Corporation Foundation of China(No.2012DFG51540)
文摘Hot deformation behavior and globularization mechanism of Ti6A14V0.1B alloy with lamellar micro structure were quantitatively studied through isothermal compression tests with the temperature range of 850950 ℃and strain rate range of 0.011.00 s1. The results show that the peak flow stress and steady stress are sensitive to the strain rate and temperature. The value of deformation activation energy is 890.49 kJmo11 in (a+β) region. Dynamic recrystallization is the major deformation mecha nism. Flow softening is dominated by dynamic recrystallization at 850950 ℃. TiB particles promote the recrystallization of laths. Globularization processes consist of four steps: for mation of subgrain after dynamic recovery in a plates; subgrain boundary migration caused by interracial instability; interfacial migration promoting phase wedge into a phase; disintegrating of a laths by diffusion processes; and grain boundary sliding. Globularization mechanisms during hot deformation processes of the Ti6A14V0.1B alloy with lamellar structure are continuous dynamic recrystallization.
基金Supported by National Natural Science Foundation of China(Grant No.51375059)National Hi-tech Research and Development Program of China(863 Program,Grant No.2011AA040203)+1 种基金Special Fund for Agro-scientific Research in the Public Interest of China(Grant No.201313009-06)National Key Technology R&D Program of the Ministry of Science and Technology of China(Grant No.2013BAD17B06)
文摘The solution for the forward displacement analysis(FDA) of the general 6-6 Stewart mechanism(i.e., the connection points of the moving and fixed platforms are not restricted to lying in a plane) has been extensively studied, but the efficiency of the solution remains to be effectively addressed. To this end, an algebraic elimination method is proposed for the FDA of the general 6-6 Stewart mechanism. The kinematic constraint equations are built using conformal geometric algebra(CGA). The kinematic constraint equations are transformed by a substitution of variables into seven equations with seven unknown variables. According to the characteristic of anti-symmetric matrices, the aforementioned seven equations can be further transformed into seven equations with four unknown variables by a substitution of variables using the Grobner basis. Its elimination weight is increased through changing the degree of one variable, and sixteen equations with four unknown variables can be obtained using the Grobner basis. A 40th-degree univariate polynomial equation is derived by constructing a relatively small-sized 9 × 9 Sylvester resultant matrix. Finally, two numerical examples are employed to verify the proposed method. The results indicate that the proposed method can effectively improve the efficiency of solution and reduce the computational burden because of the small-sized resultant matrix.
基金Project supported by the Scientific and Technological Research Program of Chongqing Municipal Education Commission(KJ1601215,KJ15012002)the Ministry of Education “Chunhui Plan”(Z2016177)
文摘The reaction mechanism of 2-methoxybenzaldehyde, 4-bromo-indanone, malononitrile and ammonium acetate one-pot to form 6-(2-methoxyphenyl)-2-amino-6-bromo-5 Hindeno[1,2-b]pyridine-3-carbonitrile was studied by density functional theory. The geometries of the reactants, transition states, intermediates and products were optimized at the PW91/DNP level. Vibration analysis was carried out to confirm the transition state structure. Reaction pathways were investigated in this study. The result indicates that the reaction Re→ TSB1→IMB1→ TSB2→ IMB2→TSB3→IMB3→TSB4→IMB4→TSB5→IMB5→TSB6→IMB6→TSB7→IMB7→ TSB8→IMB8→TSB9→IMB9→P2 is the main pathway, the activation energy of which is the lowest. The dominant product predicted theoretically is in agreement with the experiment results.
基金Supported by Key Project of Natural Science Research of Anhui Education De-partment(KJ2007A095)
文摘The original Bacillus subtilis was isolated from the soil of an apple orchard,and B. subtilis strain BS80-6,selected from Bacillus subtilis by ion implantation,was used as an antagonist for postharvest biological control against apple anthracnose( colletotrichum gloeosporioides). The mechanisms of action and efficacy of Bacillus subtilis strain BS80-6 against apple anthracnose caused by colletotrichum gloeosporioides were studied in vitro and on apples in controlled and semi-commercial conditions. An application of cell suspension( 108 cells per mL) of the antagonist in artificial wounds of apples reduced growth of C. gloeosporioides after storage at different temperatures. The inhibitory actions of cell culture to hyphal growth and to spores germination were 86. 6% and 98. 65%,respectively,and the control efficacy of cell culture against the disease was 60. 34% at room temperature. The results showed that BS80-6 was more effective against apple anthracnose.The cell culture of BS80-6 received better control efficacy against apple anthracnose than culture filtrates and autoclaved cell. All treatments significantly inhibited the disease both in vitro and in vivo compared with control. Fruits treated with cell culture and stored at 10 ℃ had lower infection rate,more delayed formation of acervwlus and smaller lesion diameter than those stored at 20 ℃. There was better control efficacy in fruits inoculated with spores after application of BS80-6. The mechanisms of BS80-6 activity appeared to involve production of an antifungal substance,deformation of hyphal cell and disintegration of cell wall. Besides,BS80-6 could improve the activity of major defense enzymes of apple,such as peroxidase( POD) and polyphenol oxidase( PPO).
基金Project supported by the National Basic Research Program of China(Grant No.2013CB632506)the National Natural Science Foundation of China(Grant Nos.51202132 and 51002087)
文摘The thermoelectric properties of Sr0.61Ba0.39Nb2O6-δ ceramics, reduced in different conditions, are investigated in the temperature range from 323 K to 1073 K. The electrical transport behaviors of the samples are dominated by the thermal-activated polaron hopping in the low temperature range, the Fermi glass behavior in the middle temperature range, and the Anderson localized behavior in the high temperature range. The thermal conductivity presents a plateau at high- temperatures, indicating a glass-like thermal conduction behavior. Both the thermoelectric power factor and the thermal conductivity increase with the increase of the degree of oxygen-reduction. Taking these two factors into account, the oxygen-reduction can still contribute to promoting the thermoelectric figure of merit. The highest ZT value is obtained to be -0.19 at 1073 K in the heaviest oxygen reduced sample.
基金Supported by the Yunnan Provincial Science and Technology Department(No. 2003A0003M)
文摘The photochemical reaction of bicyclo[4.1.0]heptane was studied at the complete active space SCF(CASSCF) level with a 6-31G^* basis set. A muhireference MP2 algorithm that has been implemented in the Gaussian program was used to correct the energetics for the dynamic correlation. Starting from the Franck-Condon excitation of bicyclo [ 4.1.0 ] heptane, the reaction is via two bonds' breakage to give rise to 1,6-heptdiene. One internal conversion (IC) and two intersystem crossing points(ISC) were located and are discussed separately. The reaction proceeds to its own characteristic product on the ground state.
基金Supported by the National Natural Science Foundation of China(No.81400403)the International Science and Technology Cooperation Program of Jilin Province(No.20110733)the Technology Program of Soochow City(No.SYS201375)
文摘AIM: To compare three kinds of fluorescent probes for in vitro labeling and in vivo tracking of endothelial progenitor cells(EPCs) in a mouse model of laser-induced retinal injury.METHODS: EPCs were isolated from human umbilical cord blood mononuclear cells and labeled with three different fluorescent probes: 5-(and-6)-carboxyfluorescein diacetate succinimidyl ester(CFSE), 1,1′-dilinoleyl-3,3,3′,3′-tetramethylindo-carbocyanine perchlorate linked acetylated low-density lipoprotein(Di I-Ac LDL), and green fluorescent protein(GFP). The fluorescent intensity of EPCs was examined by confocal microscopy. Survival rate of labeled EPCs was calculated with trypan blue staining, and their adhesive capability was assessed. A mouse model of retinal injury was induced by laser, and EPCs were injected into the vitreous cavity. Frozen section and fluorescein angiography on flat-mounted retinal samples was employed to track the labeled EPCs in vivo.RESULTS: EPCs labeled with CFSE and Di I-Ac LDL exhibited an intense green and red fluorescence at the beginning; the fluorescence intensity decreased gradually to 20.23% and 49.99% respectively, after 28 d. On the contrary, the florescent intensity of GFP-labeled EPCs increased in a time-dependent manner. All labeled EPCs showed normal morphology and no significant change in survival and adhesive capability. In the mouse model, transplantation of EPCs showed a protective effect against retinal injury. EPCs labeled with CFSE and Di I-Ac LDL were successfully tracked in mice during the development of retinal injury and repair; however, GFP-labeled EPCs were not detected in the laser-injured mouse retina.CONCLUSION: The three fluorescent markers used in this study have their own set of advantages and disadvantages. CFSE and Di I-Ac LDL are suitable for short-term EPClabeling, while GFP should be used for long-term labeling. The choice of fluorescent markers should be guided by the purpose of the study.
基金supported by the Joint Program of the National Natural Science Foundation of China(U1808216)the National Natural Science Foundation of China(Grant No.52275331)+2 种基金the Key Research and Development Program of Hubei Province(No.2022BAA011)the Academic Frontier Youth Team(2018QYTD04)at Huazhong University of Science and Technology(HUST)the Laboratory Project of Science and Technology on Power Beam Processes Laboratory and the Hong Kong Scholars Program(No.XJ2022014).
文摘The porous metallic biomaterials have attracted significant attention for implants because their lower young's modulus matches the human bones, which can eliminate the stress shielding effect and facilitate the growth of bone tissue cells. The porous metallic biomaterials fabricated by selective laser melting (SLM) have broad prospects, but the surface of the SLM-built porous structure has been severely adhered with unmelted powders, which affects the forming accuracy and surface quality. The porous metallic biomaterials face the corrosion problem of complex body fluid environments during service, so their corrosion resistance in the human body is extremely important. The surface quality will affect the corrosion resistance of the porous metallic biomaterials. Therefore, it is necessary to study the effect of post-treatment on the corrosion resistance of SLMed samples. In this work, the mechanical response and the electrochemical corrosion behavior in simulated body fluid of diamond and pentamode metamaterials Ti-6Al-4V alloy fabricated by SLM before and after sandblasting were studied. After sandblasting, the mechanical properties of the two porous metallic biomaterials were slightly improved, and the self-corrosion potential and pitting potential were more negative;meanwhile, the self-corrosion current density and passive current density increased, indicating that its corrosion performance decreased, and the passive film stability of sandblasted samples got worse.