The oxygen reduction reaction(ORR)could be effectively regulated by adjusting electron configurations and optimizing chemical bonds.Herein,we have achieved the modulation of electron distribution in Fe single atomic(F...The oxygen reduction reaction(ORR)could be effectively regulated by adjusting electron configurations and optimizing chemical bonds.Herein,we have achieved the modulation of electron distribution in Fe single atomic(Fe_(SA))sites through Fe atomic clusters(Fe_(AC))via a confined pyrolysis approach,thereby enhancing their intrinsic ORR activity.X-ray absorption spectroscopy has confirmed that the presence of iron atomic dusters could influence the electron distribution at Fe-N_(4)sites.The Fe_(SA)/Fe_(AC)-NC catalyst exhibits a half-wave potential of 0.88 V,surpassing the individual Fe_(SA)-NC structure.Through electronic structure analysis,it could be seen that iron atom clusters can affect Fe-N_(4)sites through long-range effects,and then effectively lower reaction barriers and enhance the reaction kinetics at Fe-N_(4)sites.The synthetic approach might pave the way for constructing highly active catalysts with tunable atomic structures,representing an effective and universal technique for electron modulation in M-N-C systems.This work provides enlightenment for the exploration of more efficient single-atom electrocatalysts and the optimization of the performance of atomic electrocatalysts.Furthermore,a zinc-air battery assembled using it on their cathode deliver a high peak power density(205.7 mW cm^(-2))and a high-specific capacity of 807.5 mA h g^(-1).This study offers a fresh approach to effectively enhance the synergistic interaction of between Fe single atom and Fe atomic clusters for improving ORR activity and energy storage.展开更多
As a representative of the third generation advanced high-strength steels(AHSSs),medium Mn steels(MMS)have broad development prospects in the field of automobile manufacturing.MMS with typical austenite reversion trea...As a representative of the third generation advanced high-strength steels(AHSSs),medium Mn steels(MMS)have broad development prospects in the field of automobile manufacturing.MMS with typical austenite reversion treatment have a soft duplex microstructure,i.e.ferrite+austenite,presenting a high ductility but a low yield strength.Here we show that a flash heating and cooling after austenite reversion treatment can replace the ferrite with strong martensite,which greatly enhances the yield strength of a 0.25C-4Mn steel by about 461–886 MPa.By adjusting the reversion temperature before the flash treatment,the C and Mn concentrations of reverted austenite can be altered,which determine the fraction of reverted austenite surviving the flash treatment.In addition,the mechanical stability of final retained austenite is also linked to the reversion temperature,resulting different work hardening behaviors due to transformation induced plasticity(TRIP)effect.By tweaking the reversion temperature before the flash treatment,an optimized combination of strength and ductility can be achieved.The micromechanical differences caused by the replacement of the matrix are also investigated via in-situ digital image correlation method.展开更多
Electrocatalysis for the oxygen evolution reactions(OER)has attracted much attention due to its important role in water splitting and rechargeable metal-air batteries.Therefore,designing highly efficient and low-cost ...Electrocatalysis for the oxygen evolution reactions(OER)has attracted much attention due to its important role in water splitting and rechargeable metal-air batteries.Therefore,designing highly efficient and low-cost catalysts for OER process is essential as the conventional catalysts still rely on precious metals.Transition metal-based compounds have been widely investigated as active OER catalysts,and renewed interest in the high valence metals engineered compounds has been achieved for superior catalytic activity and stability.However,an in-depth understanding of the construction strategies and induced effects for the high valence metals engineered catalysts is still lacking and desired.In this review,we have summarized the construction strategies of high valence metals as dopants or formed heterostructures with the iron/cobalt/nickel(Fe/Co/Ni)-based catalysts.Then the induced effects on Fe/Co/Ni-based catalysts by incorporating high valence metals,e.g.,accelerating the surface reconstruction,forming amorphous structure,generating vacancies/defects,and acting as stabilizers,are highlighted.The impacts of high valence metals on OER performance are elucidated based on different elements,including molybdenum(Mo),tungsten(W),cerium(Ce),vanadium(V),chromium(Cr),manganese(Mn),niobium(Nb),zirconium(Zr).The correlations of construction strategies,induced effects,catalytic activity and OER reaction pathways are elaborated.Finally,the remaining challenges for further enhancements of OER performance induced by high valence metals are presented.展开更多
Four exogenous phenolic acids, including salicylic acid, fumalic acid, p-coumaric acid and p-hydroxybenzonic acid, were used to investigate the regulatory effects on allelopathy of a wild rice accession of S37 （Oryza...Four exogenous phenolic acids, including salicylic acid, fumalic acid, p-coumaric acid and p-hydroxybenzonic acid, were used to investigate the regulatory effects on allelopathy of a wild rice accession of S37 （Oryza Iongistaminata）, which is a known allelopathic rice. The four exogenous phenolic acids induced the enhancement of the allelopathic potential of wild rice S37 in target weeds though the weed-suppressive activities were low, and the inducible effects were dependent on the specific phenolic acid, concentration and treatment time. After foliar application of exogenous phenolic acids, the inhibition rates for plant height, root length and fresh weight of barnyard grass （Echinochioa crus-galli） were significantly higher than those of the control. Especially at the concentration of 100 mg/L, the inhibition rates for plant height and fresh weight of barnyard grass by fumalic acid were 38.12% and 26.31% higher than those of the control, showing that fumalic acid was more effective compared with other phenolic acids in inhibiting monocotyledon weed growth. Furthermore, the weedsuppressive activity of aqueous extract from the leaves of wild rice S37 treated with exogenous phenolic acids was increased, and it peaked at 48 h after the treatment with the aqueous extract, and then gradually declined.展开更多
The corneal crosslinking （CXL） with riboflavin and ultraviolet-A （UVA） is a new therapy method to successfully treat infectious keratitis in clinical practice. However, there are rare reports on the complications ...The corneal crosslinking （CXL） with riboflavin and ultraviolet-A （UVA） is a new therapy method to successfully treat infectious keratitis in clinical practice. However, there are rare reports on the complications of CXL such as the secondary keratitis. The diverse clinical outcomes on keratitis have highlighted the necessity to further evaluate the efficacy and complications of CXL. We reviewed the positive and negative reports on UVA/riboflavin related with keratitis and provided our opinion on the therapeutic and side effect of UVA/riboflavin crosslinking on keratitis.展开更多
The microstructures and mechanical properties of ferrite-based lightweight steel with different compositions were investigated by tensile test,scanning electron microscopy（SEM）,transmission electron microscopy（TEM...The microstructures and mechanical properties of ferrite-based lightweight steel with different compositions were investigated by tensile test,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,X-ray diffraction（XRD）and thermodynamic calculation（TC）.It was shown that the ferrite-based lightweight steels with 5wt.%or 8wt.%Al were basically composed of ferrite,austenite andκ-carbide.As the annealing temperature increased,the content of the austenite in the steel gradually increased,while theκ-carbide gradually decomposed and finally disappeared.The mechanical properties of the steel with 5wt.%Al and 2wt.%Cr,composed of ferrite and Cr7C3carbide at different annealing temperatures,were significantly inferior to those of others.The steel containing 5wt.%Al,annealed at 820°C for 50sthen rapidly cooled to 400°C and held for 180s,can obtain the best product of strength and elongation（PSE）of 31242MPa·%.The austenite stability of the steel is better,and its PSE is higher.In addition,the steel with higher PSE has a more stable instantaneous strain hardening exponent（n value）,which is mainly caused by the effect of transformation induced plasticity（TRIP）.When theκ-carbide or Cr7C3carbide existed in the microstructure of the steel,there was an obvious yield plateau in the tensile curve,while its PSE decreased significantly.展开更多
Due to the induced polarization(IP)eff ect,the sign reversal often occurs in timedomain airborne electromagnetic(AEM)data.The inversions that do not consider IP eff ect cannot recover the true umderground electrical s...Due to the induced polarization(IP)eff ect,the sign reversal often occurs in timedomain airborne electromagnetic(AEM)data.The inversions that do not consider IP eff ect cannot recover the true umderground electrical structures.In view of the fact that there are many parameters of airborne induced polarization data in time domain,and the sensitivity diff erence between parameters is large,which brings challenges to the stability and accuracy of the inversion.In this paper,we propose an inversion mehtod for time-domain AEM data with IP effect based on the Pearson correlation constraints.This method uses the Pearson correlation coeffi cient in statistics to characterize the correlation between the resistivity and the chargeability and constructs the Pearson correlation constraints for inverting the objective function to reduce the non uniqueness of inversion.To verify the eff ectiveness of this method,we perform both Occam’s inversion and Pearson correlation constrained inversion on the synthetic data.The experiments show that the Pearson correlation constrained inverison is more accurate and stable than the Occam’s inversion.Finally,we carried out the inversion to a survey dataset with and without IP eff ect.The results show that the data misfit and the continuity of the inverted section are greatly improved when the IP eff ect is considered.展开更多
In this work, we focus on the optical super-resolution effect induced by strong nonlinear saturation absorption(NSA) of graphene oxide(GO) membranes. The third-order optical nonlinearities are characterized by the can...In this work, we focus on the optical super-resolution effect induced by strong nonlinear saturation absorption(NSA) of graphene oxide(GO) membranes. The third-order optical nonlinearities are characterized by the canonical Z-scan technique under femtosecond laser(wavelength: 800 nm, pulse width: 100 fs) excitation. Through controlling the applied femtosecond laser energy, NSA of the GO films can be tuned continuously. The GO film is placed at the focal plane as a unique amplitude filter to improve the resolution of the focused field. A multi-layer system model is proposed to present the generation of a deep sub-wavelength spot associated with the nonlinearity of GO films. Moreover, the parameter conditions to achieve the best resolution(~λ/6) are determined entirely. The demonstrated results here are useful for high density optical recoding and storage, nanolithography, and super-resolution optical imaging.展开更多
Total ionizing dose responses of different transistor geometries after being irradiated by ^（60）Co γ-rays, in 0.13-μm partially-depleted silicon-on-insulator（PD SOI） technology are investigated. The negative thr...Total ionizing dose responses of different transistor geometries after being irradiated by ^（60）Co γ-rays, in 0.13-μm partially-depleted silicon-on-insulator（PD SOI） technology are investigated. The negative threshold voltage shift in an n-type metal-oxide semiconductor field effect transistor（nMOSFET） is inversely proportional to the channel width due to radiation-induced charges trapped in trench oxide, which is called the radiation-induced narrow channel effect（RINCE）.The analysis based on a charge sharing model and three-dimensional technology computer aided design（TCAD） simulations demonstrate that phenomenon. The radiation-induced leakage currents under different drain biases are also discussed in detail.展开更多
Chemical effects in different aqueous solutions induced by plasma with glow discharge electrolysis (GDE) and contact glow discharge electrolysis (CGDE) are described in this paper. The experimental and discharge char...Chemical effects in different aqueous solutions induced by plasma with glow discharge electrolysis (GDE) and contact glow discharge electrolysis (CGDE) are described in this paper. The experimental and discharge characteristics are also reviewed. These are followed by a discussion of their mechanisms of both anodic and cathodic CGDE..展开更多
Five groups of rats (40 rats per group) were given five different varieties of Chinese tea (1 g/50 ml) and another two groups of rats (a positive control and a negative control) were given tap water as drinking water....Five groups of rats (40 rats per group) were given five different varieties of Chinese tea (1 g/50 ml) and another two groups of rats (a positive control and a negative control) were given tap water as drinking water. Except for the negative control group, all the animals were intubated with A'-nitrosomethyibenzylamine (NMBzA, 5 mg/kg body wt/week). Half of the animals in each group were sacrificed after 6 weeks and the remaining animals at the end of 12 weeks. The incidences of esophageal mucosa lesions (16-59%) at the end of6 weeks were significantly lower in the tea-treated rats than in the positive control group (100%). The incidences of esophageal tumor at the end of 12 weeks (42-67%) were also significantly lower in the tea-treated groups than in the positive control group (90%). The same phenomenon was found with respect to the size and number of tumors in each tumor-bearing animal. The relative anticarcinogenic effects of the five varieties of Chinese tea were different. The Fujian oolong tea and jasmine tea exhibited the strongest effects. The results suggest that Chinese tea can effectively inhibit the carcinogenesis Caused by an N-nitroso compound. 1990 Academic Press.Inc.展开更多
Radiation encephalopathy is the main complication of cranial radiotherapy. It can cause necrosis of brain tissue and cognitive dysfunction. Our previous work had proved that a natural antioxidant shikonin possessed pr...Radiation encephalopathy is the main complication of cranial radiotherapy. It can cause necrosis of brain tissue and cognitive dysfunction. Our previous work had proved that a natural antioxidant shikonin possessed protective effect on cerebral ischemic injury. Here we investigated the effects of shikonin on carbon ion beam induced radiation brain injury in mice. Pretreatment with shikonin significantly increased the SOD and CAT activities and the ratio of GSH/GSSG in mouse brain tissues compared with irradiated group （P〈0.01）, while obviously reduced the MDA and PCO contents and the RO$ levels derived from of the brain mitochondria.展开更多
Human lymphocytes pre-exposed to 10 mGy or 50 mGy of X-rays become less sensitive to subsequent large dose irradiation, exhibited lower rate of chromosome aberration than expected. This adaptive response could be inhi...Human lymphocytes pre-exposed to 10 mGy or 50 mGy of X-rays become less sensitive to subsequent large dose irradiation, exhibited lower rate of chromosome aberration than expected. This adaptive response could be inhibited by cycloheximide, a protein synthesis inhibitor for successive 2 h period ranging from 0.5h before to 4h after the low dose exposure, indicating that the adaptive response was directly related with the protein synthesis.展开更多
Based on an analytical solution of the two-dimensional Poisson equation in the subthreshold region, this paper investigates the behavior of DIBL （drain induced barrier lowering） effect for short channel 4H-SiC metal...Based on an analytical solution of the two-dimensional Poisson equation in the subthreshold region, this paper investigates the behavior of DIBL （drain induced barrier lowering） effect for short channel 4H-SiC metal semiconductor field effect transistors （MESFETs）. An accurate analytical model of threshold voltage shift for the asymmetric short channel 4H-SiC MESFET is presented and thus verified. According to the presented model, it analyses the threshold voltage for short channel device on the L/a （channel length/channel depth） ratio, drain applied voltage VDS and channel doping concentration ND, thus providing a good basis for the design and modelling of short channel 4H-SiC MESFETs device.展开更多
In order to analyze the Oslbglu4 phenotype, the inducible promoter of the transgenic rice which knock-down the Oslbglu4 expression was assessed. The result showed that 30 μM dexamethasone（DEX） had the stronger indu...In order to analyze the Oslbglu4 phenotype, the inducible promoter of the transgenic rice which knock-down the Oslbglu4 expression was assessed. The result showed that 30 μM dexamethasone（DEX） had the stronger induction effect than 10 μM DEX by β-Glucuronidase （GUS） staining, qRT-PCR further verified the Oslbglu4 gene deletion. The effect of DEX and its solvent absolute ethanol on seed development was measured, and no significant effect was observed. The conclusion is that final concentration of DEX at 30 μM is suitable for pOp6 promoter induction.展开更多
Electromagnetic V-shape bending of small size sheet blank is investigated numerically and experimentally. Three-dimensional electromagnetic field models are established to calculate the magnetic force distribution on ...Electromagnetic V-shape bending of small size sheet blank is investigated numerically and experimentally. Three-dimensional electromagnetic field models are established to calculate the magnetic force distribution on the sheet by software ANSYS / EMAG. Series of electromagnetic V-shape bending forming experiments are presented,in which small size uniform pressure coil and big size round flat spiral coil are used. The results show that small size uniform pressure coil is not suitable for electromagnetic forming of small size flat sheet,and the coil is susceptible to failure such as bulging,ablation and cracking. When the plane dimension of round flat spiral coil is bigger than sheet blank sizes,the induced current crowding effect will be resulted which seriously influence the magnetic force distribution on the sheet. In this case,magnetic force distribution can be adjusted through the change of the relative position between coil and sheet,the desired deformation can be obtained finally. Therefore,big size round flat spiral coil can be well applied to electromagnetic V-shape bending forming of small size flat sheet.展开更多
Increased sedimentation rates have been attributed to increased anthropogenic activity in watersheds throughout Florida and many parts of the world. The Manatee River, located on the west coast of Florida （USA）, lik...Increased sedimentation rates have been attributed to increased anthropogenic activity in watersheds throughout Florida and many parts of the world. The Manatee River, located on the west coast of Florida （USA）, like many other coastal watersheds, has experienced depletion in natural resources, increased nutrient loading, and increased pollution. LARs （linear accumulation rates） from watersheds throughout Florida suggest that anthropogenic activity increased bulk sedimentation by as much as 4-fold. The objective of this study was to construct a record of sedimentation and improve upon previous studies by determining individual sedimentary constituent MARs （mass accumulation rates） based on short lived radioisotopes （2~~pb and 234Th） to characterize changes in sedimentation attributed to increased anthropogenic development. This study constructed records of sedimentary accumulation rates to compare pre-development records to the past 100 years of anthropogenic development and identified specific changes in sedimentation attributed to anthropogenic activity. Anthropogenic development increased deposition of terrigenous material into the river from 2-fold to I 0-fold （0.3-2.0 g/cm2/yr） over three periods： （1） predevelopment period （1900-1941）; （2） agricultural development period （1941-1970）; （3） urban development period （1970-2010）. The mobilization of this amount of terrigenous material has implications for effects on water quality and biological communities within the river.展开更多
Input/output devices for flash memory are exposed to gamma ray irradiation. Total ionizing dose has been shown great influence on characteristic degradation of transistors with different sizes. In this paper, we obser...Input/output devices for flash memory are exposed to gamma ray irradiation. Total ionizing dose has been shown great influence on characteristic degradation of transistors with different sizes. In this paper, we observed a larger increase of off-state leakage in the short channel device than in long one. However, a larger threshold voltage shift is observed for the narrow width device than for the wide one, which is well known as the radiation induced narrow channel effect. The radiation induced charge in the shallow trench isolation oxide influences the electric field of the narrow channel device. Also, the drain bias dependence of the off-state leakage after irradiation is observed, which is called the radiation enhanced drain induced barrier lowing effect. Finally, we found that substrate bias voltage can suppress the off-state leakage, while leading to more obvious hump effect.展开更多
Uniaxial strain induced ferroelectric phase transitions in rutile TiO2 are investigated by first-principles calculations. The calculated results show that the in-plane tensile strain induces rutile TiO2, paraelectric ...Uniaxial strain induced ferroelectric phase transitions in rutile TiO2 are investigated by first-principles calculations. The calculated results show that the in-plane tensile strain induces rutile TiO2, paraelectric phase with P4-2/mnm （D4h） space group, to a ferroelectric phase with Pm（Cs） space group, driven by the softening behaviour of the Eul mode. In addition, the out-of-plane tensile strain, vertical to the ab plane, leads to a ferroelectric phase with P42nm （C4v） space group, driven by the softening behaviour of the A2u mode. The critical tensile strains are 3.7% in-plane and 4.0% out-of-plane, respectively. In addition, the in-plane compression strain, which has the same structure variation as out- of-plane tensile strain due to Poisson effect, leads the paraelectric rutile TiO2 to a paraelectric phase with Pnnm （D2h） space group driven by the softening behaviour of the B1g mode. These results indicate that the sequence ferroelectric （or paraelectric） phase depends on the strain applied. The origin of ferroelectric stabilization in rutile TiO2 is also discussed briefly in terms of strain induced Born effective charge transfer.展开更多
We analyze in this work anisotropic heat conduction induced by a harmonically oscillating laser source incident on rotating conductors, exploiting an analogy with an effect discovered long ago, called the Zel’dovich ...We analyze in this work anisotropic heat conduction induced by a harmonically oscillating laser source incident on rotating conductors, exploiting an analogy with an effect discovered long ago, called the Zel’dovich effect. We re-covered the main results of a recently published paper that predicts the translational Doppler frequency shift of a thermal wave induced on a sample moving with uniform rectilinear motion. We extend then this framework to take into account the frequency shift of a thermal field propagating on a rotating platform. We show that it coincides with the rotational frequency shift which has been recently observed on surface acoustic waves and hydrodynamic surface waves, called rotational superradiance. Finally, we use an analogy with the Tolman effect to deduce a simple estimate of the average temperature gradient induced by rotation, showing the existence of a new cooling effect associated with heat torque transfer.展开更多
基金supported by the National Natural Science Foundations of China(Nos:22271018,22309012 and 22302013)the NSF of Guangdong Province(Nos:2023A1515010554 and 2024A1515010307)。
文摘The oxygen reduction reaction(ORR)could be effectively regulated by adjusting electron configurations and optimizing chemical bonds.Herein,we have achieved the modulation of electron distribution in Fe single atomic(Fe_(SA))sites through Fe atomic clusters(Fe_(AC))via a confined pyrolysis approach,thereby enhancing their intrinsic ORR activity.X-ray absorption spectroscopy has confirmed that the presence of iron atomic dusters could influence the electron distribution at Fe-N_(4)sites.The Fe_(SA)/Fe_(AC)-NC catalyst exhibits a half-wave potential of 0.88 V,surpassing the individual Fe_(SA)-NC structure.Through electronic structure analysis,it could be seen that iron atom clusters can affect Fe-N_(4)sites through long-range effects,and then effectively lower reaction barriers and enhance the reaction kinetics at Fe-N_(4)sites.The synthetic approach might pave the way for constructing highly active catalysts with tunable atomic structures,representing an effective and universal technique for electron modulation in M-N-C systems.This work provides enlightenment for the exploration of more efficient single-atom electrocatalysts and the optimization of the performance of atomic electrocatalysts.Furthermore,a zinc-air battery assembled using it on their cathode deliver a high peak power density(205.7 mW cm^(-2))and a high-specific capacity of 807.5 mA h g^(-1).This study offers a fresh approach to effectively enhance the synergistic interaction of between Fe single atom and Fe atomic clusters for improving ORR activity and energy storage.
基金National Key R&D Program of China(Grant Nos.2022YFE0110800 and 2022YFB3705300)the National Natural Science Foundation of China(Grant Nos.52104380 and 52171123)for grant and financial support.
文摘As a representative of the third generation advanced high-strength steels(AHSSs),medium Mn steels(MMS)have broad development prospects in the field of automobile manufacturing.MMS with typical austenite reversion treatment have a soft duplex microstructure,i.e.ferrite+austenite,presenting a high ductility but a low yield strength.Here we show that a flash heating and cooling after austenite reversion treatment can replace the ferrite with strong martensite,which greatly enhances the yield strength of a 0.25C-4Mn steel by about 461–886 MPa.By adjusting the reversion temperature before the flash treatment,the C and Mn concentrations of reverted austenite can be altered,which determine the fraction of reverted austenite surviving the flash treatment.In addition,the mechanical stability of final retained austenite is also linked to the reversion temperature,resulting different work hardening behaviors due to transformation induced plasticity(TRIP)effect.By tweaking the reversion temperature before the flash treatment,an optimized combination of strength and ductility can be achieved.The micromechanical differences caused by the replacement of the matrix are also investigated via in-situ digital image correlation method.
基金supported by the Australian Research Council(ARC)through the Discovery Project(DP180102297)the Future Fellow Project(FT180100705)+2 种基金the support from the Open Project of State Key Laboratory of Advanced Special Steelthe Shanghai Key Laboratory of Advanced Ferrometallurgy,Shanghai University(SKLASS 2021-**)the Science and Technology Commission of Shanghai Municipality(No.19DZ2270200,20511107700)。
文摘Electrocatalysis for the oxygen evolution reactions(OER)has attracted much attention due to its important role in water splitting and rechargeable metal-air batteries.Therefore,designing highly efficient and low-cost catalysts for OER process is essential as the conventional catalysts still rely on precious metals.Transition metal-based compounds have been widely investigated as active OER catalysts,and renewed interest in the high valence metals engineered compounds has been achieved for superior catalytic activity and stability.However,an in-depth understanding of the construction strategies and induced effects for the high valence metals engineered catalysts is still lacking and desired.In this review,we have summarized the construction strategies of high valence metals as dopants or formed heterostructures with the iron/cobalt/nickel(Fe/Co/Ni)-based catalysts.Then the induced effects on Fe/Co/Ni-based catalysts by incorporating high valence metals,e.g.,accelerating the surface reconstruction,forming amorphous structure,generating vacancies/defects,and acting as stabilizers,are highlighted.The impacts of high valence metals on OER performance are elucidated based on different elements,including molybdenum(Mo),tungsten(W),cerium(Ce),vanadium(V),chromium(Cr),manganese(Mn),niobium(Nb),zirconium(Zr).The correlations of construction strategies,induced effects,catalytic activity and OER reaction pathways are elaborated.Finally,the remaining challenges for further enhancements of OER performance induced by high valence metals are presented.
基金funded by the Natural Science Foundation of Yunnan Province,China(Grant No.2007C238M)
文摘Four exogenous phenolic acids, including salicylic acid, fumalic acid, p-coumaric acid and p-hydroxybenzonic acid, were used to investigate the regulatory effects on allelopathy of a wild rice accession of S37 （Oryza Iongistaminata）, which is a known allelopathic rice. The four exogenous phenolic acids induced the enhancement of the allelopathic potential of wild rice S37 in target weeds though the weed-suppressive activities were low, and the inducible effects were dependent on the specific phenolic acid, concentration and treatment time. After foliar application of exogenous phenolic acids, the inhibition rates for plant height, root length and fresh weight of barnyard grass （Echinochioa crus-galli） were significantly higher than those of the control. Especially at the concentration of 100 mg/L, the inhibition rates for plant height and fresh weight of barnyard grass by fumalic acid were 38.12% and 26.31% higher than those of the control, showing that fumalic acid was more effective compared with other phenolic acids in inhibiting monocotyledon weed growth. Furthermore, the weedsuppressive activity of aqueous extract from the leaves of wild rice S37 treated with exogenous phenolic acids was increased, and it peaked at 48 h after the treatment with the aqueous extract, and then gradually declined.
文摘The corneal crosslinking （CXL） with riboflavin and ultraviolet-A （UVA） is a new therapy method to successfully treat infectious keratitis in clinical practice. However, there are rare reports on the complications of CXL such as the secondary keratitis. The diverse clinical outcomes on keratitis have highlighted the necessity to further evaluate the efficacy and complications of CXL. We reviewed the positive and negative reports on UVA/riboflavin related with keratitis and provided our opinion on the therapeutic and side effect of UVA/riboflavin crosslinking on keratitis.
基金supported by the Shanghai Municipal Natural Science Foundation(Grant No.17ZR1410400)the Shanghai Municipal Science and Technology Commission(Grant Nos.15DZ2260300,15DZ2260301)
文摘The microstructures and mechanical properties of ferrite-based lightweight steel with different compositions were investigated by tensile test,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,X-ray diffraction（XRD）and thermodynamic calculation（TC）.It was shown that the ferrite-based lightweight steels with 5wt.%or 8wt.%Al were basically composed of ferrite,austenite andκ-carbide.As the annealing temperature increased,the content of the austenite in the steel gradually increased,while theκ-carbide gradually decomposed and finally disappeared.The mechanical properties of the steel with 5wt.%Al and 2wt.%Cr,composed of ferrite and Cr7C3carbide at different annealing temperatures,were significantly inferior to those of others.The steel containing 5wt.%Al,annealed at 820°C for 50sthen rapidly cooled to 400°C and held for 180s,can obtain the best product of strength and elongation（PSE）of 31242MPa·%.The austenite stability of the steel is better,and its PSE is higher.In addition,the steel with higher PSE has a more stable instantaneous strain hardening exponent（n value）,which is mainly caused by the effect of transformation induced plasticity（TRIP）.When theκ-carbide or Cr7C3carbide existed in the microstructure of the steel,there was an obvious yield plateau in the tensile curve,while its PSE decreased significantly.
基金This paper was fi nancially supported by the National Natural Science Foundation of China(Nos.42030806,41774125,41904104,41804098)the Pioneer Project of Chinese Academy of Sciences(No.XDA14020102).
文摘Due to the induced polarization(IP)eff ect,the sign reversal often occurs in timedomain airborne electromagnetic(AEM)data.The inversions that do not consider IP eff ect cannot recover the true umderground electrical structures.In view of the fact that there are many parameters of airborne induced polarization data in time domain,and the sensitivity diff erence between parameters is large,which brings challenges to the stability and accuracy of the inversion.In this paper,we propose an inversion mehtod for time-domain AEM data with IP effect based on the Pearson correlation constraints.This method uses the Pearson correlation coeffi cient in statistics to characterize the correlation between the resistivity and the chargeability and constructs the Pearson correlation constraints for inverting the objective function to reduce the non uniqueness of inversion.To verify the eff ectiveness of this method,we perform both Occam’s inversion and Pearson correlation constrained inversion on the synthetic data.The experiments show that the Pearson correlation constrained inverison is more accurate and stable than the Occam’s inversion.Finally,we carried out the inversion to a survey dataset with and without IP eff ect.The results show that the data misfit and the continuity of the inverted section are greatly improved when the IP eff ect is considered.
基金supported by the National Natural Science Foundation of China(Nos.61575139,51602213 and 11604236)the Young Science Foundation of Taiyuan University of Technology(No.2015QN066)
文摘In this work, we focus on the optical super-resolution effect induced by strong nonlinear saturation absorption(NSA) of graphene oxide(GO) membranes. The third-order optical nonlinearities are characterized by the canonical Z-scan technique under femtosecond laser(wavelength: 800 nm, pulse width: 100 fs) excitation. Through controlling the applied femtosecond laser energy, NSA of the GO films can be tuned continuously. The GO film is placed at the focal plane as a unique amplitude filter to improve the resolution of the focused field. A multi-layer system model is proposed to present the generation of a deep sub-wavelength spot associated with the nonlinearity of GO films. Moreover, the parameter conditions to achieve the best resolution(~λ/6) are determined entirely. The demonstrated results here are useful for high density optical recoding and storage, nanolithography, and super-resolution optical imaging.
基金Project supported by the Weapon Equipment Pre-Research Foundation of China(Grant No.9140A11020114ZK34147)the Shanghai Municipal Natural Science Foundation,China(Grant No.15ZR1447100)
文摘Total ionizing dose responses of different transistor geometries after being irradiated by ^（60）Co γ-rays, in 0.13-μm partially-depleted silicon-on-insulator（PD SOI） technology are investigated. The negative threshold voltage shift in an n-type metal-oxide semiconductor field effect transistor（nMOSFET） is inversely proportional to the channel width due to radiation-induced charges trapped in trench oxide, which is called the radiation-induced narrow channel effect（RINCE）.The analysis based on a charge sharing model and three-dimensional technology computer aided design（TCAD） simulations demonstrate that phenomenon. The radiation-induced leakage currents under different drain biases are also discussed in detail.
文摘Chemical effects in different aqueous solutions induced by plasma with glow discharge electrolysis (GDE) and contact glow discharge electrolysis (CGDE) are described in this paper. The experimental and discharge characteristics are also reviewed. These are followed by a discussion of their mechanisms of both anodic and cathodic CGDE..
文摘Five groups of rats (40 rats per group) were given five different varieties of Chinese tea (1 g/50 ml) and another two groups of rats (a positive control and a negative control) were given tap water as drinking water. Except for the negative control group, all the animals were intubated with A'-nitrosomethyibenzylamine (NMBzA, 5 mg/kg body wt/week). Half of the animals in each group were sacrificed after 6 weeks and the remaining animals at the end of 12 weeks. The incidences of esophageal mucosa lesions (16-59%) at the end of6 weeks were significantly lower in the tea-treated rats than in the positive control group (100%). The incidences of esophageal tumor at the end of 12 weeks (42-67%) were also significantly lower in the tea-treated groups than in the positive control group (90%). The same phenomenon was found with respect to the size and number of tumors in each tumor-bearing animal. The relative anticarcinogenic effects of the five varieties of Chinese tea were different. The Fujian oolong tea and jasmine tea exhibited the strongest effects. The results suggest that Chinese tea can effectively inhibit the carcinogenesis Caused by an N-nitroso compound. 1990 Academic Press.Inc.
基金supported by Key Program of National Natural Science Foundation of China(U1432248)National Natural Science Foundation of China(11175222,11305226)
文摘Radiation encephalopathy is the main complication of cranial radiotherapy. It can cause necrosis of brain tissue and cognitive dysfunction. Our previous work had proved that a natural antioxidant shikonin possessed protective effect on cerebral ischemic injury. Here we investigated the effects of shikonin on carbon ion beam induced radiation brain injury in mice. Pretreatment with shikonin significantly increased the SOD and CAT activities and the ratio of GSH/GSSG in mouse brain tissues compared with irradiated group （P〈0.01）, while obviously reduced the MDA and PCO contents and the RO$ levels derived from of the brain mitochondria.
文摘Human lymphocytes pre-exposed to 10 mGy or 50 mGy of X-rays become less sensitive to subsequent large dose irradiation, exhibited lower rate of chromosome aberration than expected. This adaptive response could be inhibited by cycloheximide, a protein synthesis inhibitor for successive 2 h period ranging from 0.5h before to 4h after the low dose exposure, indicating that the adaptive response was directly related with the protein synthesis.
基金Project partly supported by National Defense Basic Research Program of China (Grant No 51327010101)
文摘Based on an analytical solution of the two-dimensional Poisson equation in the subthreshold region, this paper investigates the behavior of DIBL （drain induced barrier lowering） effect for short channel 4H-SiC metal semiconductor field effect transistors （MESFETs）. An accurate analytical model of threshold voltage shift for the asymmetric short channel 4H-SiC MESFET is presented and thus verified. According to the presented model, it analyses the threshold voltage for short channel device on the L/a （channel length/channel depth） ratio, drain applied voltage VDS and channel doping concentration ND, thus providing a good basis for the design and modelling of short channel 4H-SiC MESFETs device.
基金Supported by Guizhou International Cooperation Project on Science and Technology[No.QiankehewaiG(2013)7040]The 20th Project of The Joint Committee on Scientific and Technical Cooperation between The Government of the Kingdom of Thailand and The Government of the People’s Republic of China(No.20-606J)China.Suranaree University of Technology grant number SUT3-304-54-12-29,Thailand
文摘In order to analyze the Oslbglu4 phenotype, the inducible promoter of the transgenic rice which knock-down the Oslbglu4 expression was assessed. The result showed that 30 μM dexamethasone（DEX） had the stronger induction effect than 10 μM DEX by β-Glucuronidase （GUS） staining, qRT-PCR further verified the Oslbglu4 gene deletion. The effect of DEX and its solvent absolute ethanol on seed development was measured, and no significant effect was observed. The conclusion is that final concentration of DEX at 30 μM is suitable for pOp6 promoter induction.
基金Sponsored by the National Basic Research Program of China(Grant No.2011CB012800 and 2011CB012804)
文摘Electromagnetic V-shape bending of small size sheet blank is investigated numerically and experimentally. Three-dimensional electromagnetic field models are established to calculate the magnetic force distribution on the sheet by software ANSYS / EMAG. Series of electromagnetic V-shape bending forming experiments are presented,in which small size uniform pressure coil and big size round flat spiral coil are used. The results show that small size uniform pressure coil is not suitable for electromagnetic forming of small size flat sheet,and the coil is susceptible to failure such as bulging,ablation and cracking. When the plane dimension of round flat spiral coil is bigger than sheet blank sizes,the induced current crowding effect will be resulted which seriously influence the magnetic force distribution on the sheet. In this case,magnetic force distribution can be adjusted through the change of the relative position between coil and sheet,the desired deformation can be obtained finally. Therefore,big size round flat spiral coil can be well applied to electromagnetic V-shape bending forming of small size flat sheet.
文摘Increased sedimentation rates have been attributed to increased anthropogenic activity in watersheds throughout Florida and many parts of the world. The Manatee River, located on the west coast of Florida （USA）, like many other coastal watersheds, has experienced depletion in natural resources, increased nutrient loading, and increased pollution. LARs （linear accumulation rates） from watersheds throughout Florida suggest that anthropogenic activity increased bulk sedimentation by as much as 4-fold. The objective of this study was to construct a record of sedimentation and improve upon previous studies by determining individual sedimentary constituent MARs （mass accumulation rates） based on short lived radioisotopes （2~~pb and 234Th） to characterize changes in sedimentation attributed to increased anthropogenic development. This study constructed records of sedimentary accumulation rates to compare pre-development records to the past 100 years of anthropogenic development and identified specific changes in sedimentation attributed to anthropogenic activity. Anthropogenic development increased deposition of terrigenous material into the river from 2-fold to I 0-fold （0.3-2.0 g/cm2/yr） over three periods： （1） predevelopment period （1900-1941）; （2） agricultural development period （1941-1970）; （3） urban development period （1970-2010）. The mobilization of this amount of terrigenous material has implications for effects on water quality and biological communities within the river.
文摘Input/output devices for flash memory are exposed to gamma ray irradiation. Total ionizing dose has been shown great influence on characteristic degradation of transistors with different sizes. In this paper, we observed a larger increase of off-state leakage in the short channel device than in long one. However, a larger threshold voltage shift is observed for the narrow width device than for the wide one, which is well known as the radiation induced narrow channel effect. The radiation induced charge in the shallow trench isolation oxide influences the electric field of the narrow channel device. Also, the drain bias dependence of the off-state leakage after irradiation is observed, which is called the radiation enhanced drain induced barrier lowing effect. Finally, we found that substrate bias voltage can suppress the off-state leakage, while leading to more obvious hump effect.
基金supported by the Scientific Research Foundation of the Education Department of Zhejiang Province, China (Grant No. Y200805750)
文摘Uniaxial strain induced ferroelectric phase transitions in rutile TiO2 are investigated by first-principles calculations. The calculated results show that the in-plane tensile strain induces rutile TiO2, paraelectric phase with P4-2/mnm （D4h） space group, to a ferroelectric phase with Pm（Cs） space group, driven by the softening behaviour of the Eul mode. In addition, the out-of-plane tensile strain, vertical to the ab plane, leads to a ferroelectric phase with P42nm （C4v） space group, driven by the softening behaviour of the A2u mode. The critical tensile strains are 3.7% in-plane and 4.0% out-of-plane, respectively. In addition, the in-plane compression strain, which has the same structure variation as out- of-plane tensile strain due to Poisson effect, leads the paraelectric rutile TiO2 to a paraelectric phase with Pnnm （D2h） space group driven by the softening behaviour of the B1g mode. These results indicate that the sequence ferroelectric （or paraelectric） phase depends on the strain applied. The origin of ferroelectric stabilization in rutile TiO2 is also discussed briefly in terms of strain induced Born effective charge transfer.
文摘We analyze in this work anisotropic heat conduction induced by a harmonically oscillating laser source incident on rotating conductors, exploiting an analogy with an effect discovered long ago, called the Zel’dovich effect. We re-covered the main results of a recently published paper that predicts the translational Doppler frequency shift of a thermal wave induced on a sample moving with uniform rectilinear motion. We extend then this framework to take into account the frequency shift of a thermal field propagating on a rotating platform. We show that it coincides with the rotational frequency shift which has been recently observed on surface acoustic waves and hydrodynamic surface waves, called rotational superradiance. Finally, we use an analogy with the Tolman effect to deduce a simple estimate of the average temperature gradient induced by rotation, showing the existence of a new cooling effect associated with heat torque transfer.
