Multi-energy microgrids(MEMG)play an important role in promoting carbon neutrality and achieving sustainable development.This study investigates an effective energy management strategy(EMS)for MEMG.First,an energy man...Multi-energy microgrids(MEMG)play an important role in promoting carbon neutrality and achieving sustainable development.This study investigates an effective energy management strategy(EMS)for MEMG.First,an energy management system model that allows for intra-microgrid energy conversion is developed,and the corresponding Markov decision process(MDP)problem is formulated.Subsequently,an improved double deep Q network(iDDQN)algorithm is proposed to enhance the exploration ability by modifying the calculation of the Q value,and a prioritized experience replay(PER)is introduced into the iDDQN to improve the training speed and effectiveness.Finally,taking advantage of the federated learning(FL)and iDDQN algorithms,a federated iDDQN is proposed to design an MEMG energy management strategy to enable each microgrid to share its experiences in the form of local neural network(NN)parameters with the federation layer,thus ensuring the privacy and security of data.The simulation results validate the superior performance of the proposed energy management strategy in minimizing the economic costs of the MEMG while reducing CO_2 emissions and protecting data privacy.展开更多
Objective:To investigate the clinical efficacy of acupuncture combined with emotional intervention in patients with post-stroke depression(PSD).Methods:A total of 100 patients with PSD who met the inclusion criteria w...Objective:To investigate the clinical efficacy of acupuncture combined with emotional intervention in patients with post-stroke depression(PSD).Methods:A total of 100 patients with PSD who met the inclusion criteria were randomly divided into an experimental group(50 cases)and a control group(50 cases)using the random number table method,and the enrollment was in order of admission time.The control group used conventional treatment of oral antidepressant Deanxit tablets(0.5 mg flupenthixol+10 mg melitracen)with the dose appropriately adjusted according to the patient’s medication effect,and modern rehabilitation treatment given selectively according to the patient’s condition.The experimental group had similar treatment as the control group with the addition of traditional Chinese medicine(TCM)acupuncture combined with emotional intervention.The application effects of both groups before and after treatment were verified using the Hamilton Depression Rating Scale(Ham-D),National Institutes of Health Stroke Scale(NIHSS),and Activities of Daily Living(ADL),serotonin levels were measured,and statistical analyses were carried out.Results:The total effective rate of patients in the experimental group was significantly higher than that in the control group,and the Ham-D score,NIHSS score,ADL score,and serotonin level after treatment were significantly higher than those in the control group,and the difference between the two groups was statistically significant(P<0.05).Conclusion:For patients with PSD,adding TCM acupuncture with emotional intervention on top of conventional treatment significantly improve the clinical efficacy and better improve the daily life ability of patients.展开更多
Parthenogenetic embryonic stem cells have pluripotent differentiation potentials, akin to fertilized embryo-derived embryonic stem cells. The aim of this study was to compare the neuronal differentiation potential of ...Parthenogenetic embryonic stem cells have pluripotent differentiation potentials, akin to fertilized embryo-derived embryonic stem cells. The aim of this study was to compare the neuronal differentiation potential of parthenogenetic and fertilized embryo-derived embryonic stem cells. Before differentiation, karyotype analysis was performed, with normal karyotypes detected in both parthenogenetic and fertilized embryo-derived embryonic stem cells. Sex chromosomes were identified as XX. Immunocytochemistry and quantitative real-time PCR detected high expression of the pluripotent gene, Oct4, at both the mRNA and protein levels, indicating pluripotent differentiation potential of the two embryonic stem cell subtypes. Embryonic stern cells were induced with retinoic acid to form embryoid bodies, and then dispersed into single cells. Single cells were differentiated in N2 differentiation medium for 9 days. Immunocytochemistry showed parthenogenetic and fertilized embryo-derived embryonic stem cells both express the neuronal cell markers nestin, ~lll-tubulin and myelin basic protein. Quantitative real-time PCR found expression of neuregenesis related genes (Sox-1, Nestin, GABA, Pax6, Zic5 and Pitxl) in both types of embryonic stem cells, and Oct4 expression was significantly decreased. Nestin and Pax6 expression in parthenogenetic embryonic stem cells was significantly higher than that in fertilized embryo-derived embryonic stem cells. Thus, our experimental findings indicate that parthenogenetic embryonic stem cells have stronger neuronal differentiation potential than fertilized embryo-derived embryonic stem cells.展开更多
In the competitive energy market,energy retailers are facing the uncertainties of both energy price and demand,which requires them to formulate reasonable energy purchasing and selling strategies for improving their c...In the competitive energy market,energy retailers are facing the uncertainties of both energy price and demand,which requires them to formulate reasonable energy purchasing and selling strategies for improving their competitiveness in this market.Particularly,the attractive multi-energy retail packages are the key for retailers to increase their benefit.Therefore,combined with incentive means and price signals,five types of multi-energy retail packages such as peak-valley time-of-use(TOU)price package and day-night bundled price package are designed in this paper for retailers.The iterative interactions between retailers and end-users are modeled using a bi-level model of stochastic optimization based on multi-leader multi-follower(MLMF)Stackelberg game,in which retailers are leaders and end-users are followers.Retailers make decisions to maximize the profit considering the conditional value at risk(CVaR)while end-users optimize the satisfaction of both energy comfort and economy.Besides,a distributed algorithm is proposed to obtain the Nash equilibrium of above MLMF Stackelberg game model while the particle swarm optimization(PSO)algorithm and CPLEX solver are applied to solve the optimization model for each participant(retailer or end-user).Numeral results show that the designed retail packages can increase the overall profit of retailers,and the overall satisfaction of industrial users is the highest while that of residential users is the lowest after game interaction.展开更多
Objectives Benzimidazoles(BZs)are commonly used for the treatment of soil-transmitted helminth infections in veterinary clinics;however,misuse and overdosing of BZs will cause residual problems and have the potential ...Objectives Benzimidazoles(BZs)are commonly used for the treatment of soil-transmitted helminth infections in veterinary clinics;however,misuse and overdosing of BZs will cause residual problems and have the potential to damage human health through the food chain.Thus,the existence of BZs in foods needs more attention.This study aims to establish a broad-spectrum immunoassay for rapid detection and to simultaneously monitor BZs in milk.Materials and Methods Based on structure analysis,a‘zero epitope loss’strategy,which introduced a spacer arm into the imino group of the imidazole ring of albendazole,was first adopted for hapten modification to obtain an ultra-sensitive and broad-spectrum antibody.An indirect competitive enzyme-linked immunosorbent assay(icELISA)was established for the detection of 18 BZs in milk sample with a single-step pretreatment.A quantitative structure–activity relationship model was constructed to interpret and predict the recognition.Results The antibody could recognize 20 BZs and the half-inhibitory concentrations ranged from 0.054 to 417.58 ng/mL,the limits of detection of icELISA ranged from 0.4 to 89.4 ng/mL,and the mean recovery rates ranged from 76.49%to 120.40%,with a coefficient of variation<20%.Substituent R1 of BZs was considered to be the main influencing factor for recognition,and the comparative molecular field analysis model(q2=0.724,r2=0.998)was finally chosen for further prediction.Conclusions The results indicated that the established icELISA could simultaneously identify 18 BZs,with good accuracy and precision,which was suitable for rapid detection of BZs in milk.展开更多
Long-range peripheral nerve defect is a severe and worldwide disease.With the increasing development of tissue engineering,the excellent ability of nerve extracellular matrix(ECM)in peripheral nerve injury(PNI)has bee...Long-range peripheral nerve defect is a severe and worldwide disease.With the increasing development of tissue engineering,the excellent ability of nerve extracellular matrix(ECM)in peripheral nerve injury(PNI)has been widely studied and verified.Here,we present a novel microtube that contains gradient decellularized porcine sciatic nerve ECM hydrogel(pDScNM-gel)from microfluidics for sciatic nerve regeneration.The pDScNM is confirmed to enhance cell proliferation and migration,and improve the axon growth of primary dorsal root ganglions(DRGs)in a concentration-related manner.These behaviors were also achieved when cells were co-cultured in a gradient pDScNM microtube.The in vivo sciatic nerve regeneration and functional recovery were also demonstrated by assembling the gradient pDScNM microtubes with a medical silicon tube.These results indicated that the microtubes with gradient pDScNM could act as a promising alternative for repairing peripheral nerve defects and showed great potential in clinical use.展开更多
Sliver is a common but easily neglected defect in single crystal Ni-based superalloy castings.To date,there is still no unified viewpoint on its formation mechanism and generation causes.In this work,the orientation d...Sliver is a common but easily neglected defect in single crystal Ni-based superalloy castings.To date,there is still no unified viewpoint on its formation mechanism and generation causes.In this work,the orientation discontinuity and motion behavior of sliver defects were studied through experiments and numerical simulations.The ultrathin wedge-shaped specimen containing the grain boundary of the sliver and the matrix was prepared at the initial position of the sliver defect for the observation of equal thick-ness fringes.The discontinuity of equal thickness fringes on both sides of the grain boundary was ob-served through a transmission electron microscope,which directly confirms the abrupt change in the orientation between the sliver and matrix from the nanoscale.The crystal lattices at the smooth area and the bulging area of the grain boundary were found to have unusually different arrangements.The irregular lattice arrangement at the bulging area shows that the grain boundary has experienced high-stress deformation.Statistical results of sliver orientation deviation with a further composition analysis show the micro protuberance of the mold shell has a noticeable inductive effect on the sliver generation.Furthermore,a self-developed three-dimensional phase-field simulation model coupled with the spatial topology algorithm is established to simulate the orientation deflection behavior and orientation devia-tion threshold of fractured dendrites.The simulation results indicated that there is an upper limit of the cross-section solid fraction at the fracture position for the motion of the fractured dendrites.When the cross-section solid fraction at the fracture position is higher than this upper limit,it will be difficult to produce large deviation slivers due to the structural limitation of surrounding dendrites.This upper limit does not change with the solidification temperature gradient.展开更多
Scanning speed is a critical parameter for laser process, which can play a key role in the microstruc- ture evolution of laser melting. In the laser melting of single crystal superalloy, the effects of scanning speed ...Scanning speed is a critical parameter for laser process, which can play a key role in the microstruc- ture evolution of laser melting. In the laser melting of single crystal superalloy, the effects of scanning speed were investigated by experimental analysis and computational simulation. The laser was scanning along [710] direction on (001) surface in different speeds. Solidification microstructures of dendrites growth direction and the primary dendritic spacing were analyzed by metallograph. Besides, a planar interface during solidification was taken into attention, Experiment results indicated that the primary dendritic spacing and thickness of planar interface decrease with the increase of speed. Through simu- lation, distribution of dendrites growth velocity and thermal gradient along dendrite growth direction were calculated, and the simulation of dendrites growth direction agreed with the experiment results. Additionally, a constant value was acquired which can be used to predict the primary dendritic spacing. Moreover, according to curve-fitting method and inequality relation, a model was proposed to predict the thickness of planar interface.展开更多
Fusion weld is a portable and economical joining and repairing method of metals.However,weld cracks often occur during the fusion weld of Ni-base superalloys,which hinder the applications of fusion weld on this kind o...Fusion weld is a portable and economical joining and repairing method of metals.However,weld cracks often occur during the fusion weld of Ni-base superalloys,which hinder the applications of fusion weld on this kind of materials.In this work,the effects of microstructures of grain boundaries(GBs)of the prototype M951 superalloy on its weldability were investigated.The precipitated phases,the elemental segregations on GBs,and the morphologies of GBs can be largely altered by regulating the cooling rates of pre-weld heat treatments.With decreasing the cooling rate,chain-like M_(23)X_(6)phase precipitates along the GBs,accompanying segregations of B,and GBs becomes more serrated in morphology.During fusion weld,the engineered GBs in the M951 superalloy with a low cooling rate favor the formation of the continuous liquid films on GBs,which together with the serrated GB morphology significantly prevents the formation of weld cracks.Our findings imply that the weld-crack resistance of the superalloys can be ameliorated by engineering GBs.展开更多
The effect of thermal exposure on microstructure and creep properties of a fourth-generation nickelbased single crystal superalloy was investigated.The thermal exposure of samples after the full heat treatment was car...The effect of thermal exposure on microstructure and creep properties of a fourth-generation nickelbased single crystal superalloy was investigated.The thermal exposure of samples after the full heat treatment was carried out at 1000℃,1100℃ and 1140℃ for 100 h and 200 h.The γ’ coarsening,γ’ rafting and γ channel widening were observed in samples after thermal exposure.When the thermal exposure time was constant,the morphology of γ’ phase in the alloy evolved significantly with increasing aging temperature.The interracial dislocation networks in aged samples after creep ruptured gradually became irregular and sparse with the increase of exposure temperature.When the higher exposure temperature was used,enla rgement of the defect pores was observed in samples,the microcracks were more likely to initiate and propagate at the corner of these pores.After aging at 1000℃ for 100 h,the creep life at 1140℃/137 MPa was slightly longer than that of heat-treated sample,which could be attributed to the slightly coarsened γ’ phase,homogenization of refractor elements.In contrast,the creep life of sample exposed at 1140℃ for 100 h was greatly decreased.The decrease of creep life was dominated by the rafting of γ’phase,the irregular interfacial dislocation networks as well as the enlargement of homogenization pores.展开更多
MCrAlY/TaC metal matrix composite coatings with 10, 20 and 30 wt.% TaC have been successfully produced by electrospark deposition (ESD). The effects of TaC content on microstructure, hardness and oxidation behavior ...MCrAlY/TaC metal matrix composite coatings with 10, 20 and 30 wt.% TaC have been successfully produced by electrospark deposition (ESD). The effects of TaC content on microstructure, hardness and oxidation behavior of the composite coatings were studied. The results showed that the composite coatings were composed of superfine 9' columnar dendrite and large TaC particles dispersedly distributed. The hardness was enhanced but oxidation resistance of the composite coatings was reduced with increasing TaC contents.展开更多
The detrimental effects of carbides and porosity on the fatigue crack initiation and propagation of nickel-based single-crystal superalloys have been reported by many previous studies.However,few studies have quantita...The detrimental effects of carbides and porosity on the fatigue crack initiation and propagation of nickel-based single-crystal superalloys have been reported by many previous studies.However,few studies have quantitatively compared the fatigue damaging effects of carbides and pores on the fatigue crack evolution.In this study,a high-resolution X-ray computed tomography(XCT)characterization of a DD5 nickel-based single-crystal superalloy during fatigue test was performed.The evolution of carbides,pores and cracks at all stages was observed and tracked.In order to quantify the 3D microstructures,a new damage factor that correlates the morphology of fracture surface with crack evolution behaviors was proposed.It was found that porosity was more detrimental than carbides in crack initiation and propagation during fatigue tests.Furthermore,pore spacing has been found to be the most significant factor among all controlling pore characteristics in the crack initiation stage and sphericity is the most critical pore characteristic in the crack propagation stage.Therefore,by statistically analyzing the evolution of carbides and pores during fatigue tests in this study,the underlying fatigue cracking mechanism of nickel-based superalloys is revealed.展开更多
Two alloys with different Ta and Al contents were applied to study the influence of Ta/Al ratio on the microstructural evolution and creep deformation under high temperature.The increase of Ta/Al ratio made theγ/γ...Two alloys with different Ta and Al contents were applied to study the influence of Ta/Al ratio on the microstructural evolution and creep deformation under high temperature.The increase of Ta/Al ratio made theγ/γ'lattice misfit more negative and enhanced the volume fraction ofγ'phase,which produced cubic and smallγ'phase in the initial microstructures.These initial tinyγ'phases impeded the dislocations movement and delayed the course of complete raftedγ'phase during the origination of creep deformation,which prolonged the time of the primary creep stage.Moreover,the increase of Ta/Al ratio and addition of Ru produced the denser and stable dislocation networks,the high APB energy and better solution strengthening,which hindered the climbing and sliding of dislocations,and restrained the formation of superdislocations in theγ'precipitate.The second creep stage was extended,and the minimum creep rate was reduced.Hence,the increase of whole creep life of the alloy containing high Ta/Al ratio was attributed to the prolongation of the primary and second creep stages,and the low minimum creep rate.The appearance of the topological inversion phenomenon during the tertiary creep stage was the primary cause for the sudden increase of the creep strain rate of the alloy containing low Ta/Al ratio.However,the high creep strain rate of the alloy containing high Ta/Al ratio during the tertiary creep stage was related to the occurrence and extending of the cracks near the voids.Both alloys would lose efficacy within 20 h-30 h.展开更多
The application and component designs of single crystal superalloys are restricted by the precipitation of topologically closed packed(TCP)phases,which can deteriorate the microstructural stability of the alloys sever...The application and component designs of single crystal superalloys are restricted by the precipitation of topologically closed packed(TCP)phases,which can deteriorate the microstructural stability of the alloys severely.Limited researches concerning the type and morphology evolution of TCP phases under elevated temperature conditions have been reported previously.In the present work,three Re-containing single crystal alloys were designed to investigate TCP phase evolution via long term isothermal exposure tests at 1120℃while the effects of Re on the microstructural characteristic and elements segregation were also clarified.The results showed that the addition of Re increased the instability of the alloys and the volume fraction of the TCP phases exceeded 5 vol%when the Re content reached 3 wt%.The increasing Re content had also raised the precipitation temperature of TCP phases but it did not change the type of them after long term aging;all the TCP particles were identified asμphase in this study.Moreover,the elements segregation became considerably serious as Re addition increased constantly,which brought about various morphologies of theμphase in the experimental alloys.In particular,the rod-like and needle-likeμphases demonstrated the typical orientation withinγmatrix while the blockyμphase was dispersedly distributed in the space.No specific orientation relationship could be observed in theμphase when the addition of Re exceeded certain threshold value.展开更多
Nuclear envelope proteins have important roles in chromatin organization and signal-dependent transcriptional regulation. A previous study reported that the inner nuclear membrane protein, Otefin (Ote), was essentia...Nuclear envelope proteins have important roles in chromatin organization and signal-dependent transcriptional regulation. A previous study reported that the inner nuclear membrane protein, Otefin (Ote), was essential for germline stem cell (GSC) maintenance via interaction with Smad complex. The interaction of Ore with the Smad complex recruits the barn locus to the nuclear periphery and subsequently results in bam transcriptional silencing, revealing that nuclear peripheral localization is essential for barn gene regulation. However, it remains unknown whether the nuclear peripheral localization is sufficient for barn silencing. To address this issue, we have established a tethering system, in which the Gal4 DNA binding domain (DBD) of the Flag:Gal4 DBD:Ote△LEM fusion protein physically interacts with the Gal4 binding sites upstream of bamP-gfp to artificially recruit the reporter gene gfp to the nuclear membrane. Our data demonstrated that the nuclear peripheral localization seemed to affect the expression of the target naked gene in S2 ceils. By contrast, in Drosophila germ cells, the nuclear membrane localization was not sufficient for gene silencing.展开更多
This paper gives several structure-preserving schemes for the Degasperis-Procesi equation which has bi-Hamiltonian structures consisted of both complex and non-local Hamiltonian differential operators. For this sake, ...This paper gives several structure-preserving schemes for the Degasperis-Procesi equation which has bi-Hamiltonian structures consisted of both complex and non-local Hamiltonian differential operators. For this sake, few structure-preserving schemes have been proposed so far. In our work, based on one of the bi-Hamiltonian structures, a symplectic scheme and two new energy-preserving schemes are constructed. The symplecticity comes straightly from the application of the implicit midpoint method on the semi-discrete system which is proved to remain Hamiltonian, while the energy conservation is derived by the combination of the averaged vector field method of second and fourth order, respectively. Some numerical results are presented to show that the three schemes do have the advantages in numerical stability, accuracy in long time computing and ability to preserve the invariants of the DP equation.展开更多
In this paper,a tumor immune model with time delay is studied.First,the stability of nonnegative equilibria is analyzed.Then the time delay τ is selected as a bifurcation parameter and the existence of Hopf bifurcati...In this paper,a tumor immune model with time delay is studied.First,the stability of nonnegative equilibria is analyzed.Then the time delay τ is selected as a bifurcation parameter and the existence of Hopf bifurcation is proved.Finally,by using the canonical method and the central manifold theory,the criteria for judging the direction and stability of Hopf bifurcation are given.展开更多
In this paper,we propose an explicit symplectic Fourier pseudospectral method for solving the Klein-Gordon-Schr odinger equation.The key idea is to rewrite the equation as an infinite-dimensional Hamiltonian system an...In this paper,we propose an explicit symplectic Fourier pseudospectral method for solving the Klein-Gordon-Schr odinger equation.The key idea is to rewrite the equation as an infinite-dimensional Hamiltonian system and discrete the system by using Fourier pseudospectral method in space and symplectic Euler method in time.After composing two different symplectic Euler methods for the ODEs resulted from semi-discretization in space,we get a new explicit scheme for the target equation which is of second order in space and spectral accuracy in time.The canonical Hamiltonian form of the resulted ODEs is presented and the new derived scheme is proved strictly to be symplectic.The new scheme is totally explicitwhereas symplectic scheme are generally implicit or semi-implicit.Linear stability analysis is carried and a necessary Courant-Friedrichs-Lewy condition is given.The numerical results are reported to test the accuracy and efficiency of the proposed method in long-term computing.展开更多
基金supported by the Research and Development of Key Technologies of the Regional Energy Internet based on Multi-Energy Complementary and Collaborative Optimization(BE2020081)。
文摘Multi-energy microgrids(MEMG)play an important role in promoting carbon neutrality and achieving sustainable development.This study investigates an effective energy management strategy(EMS)for MEMG.First,an energy management system model that allows for intra-microgrid energy conversion is developed,and the corresponding Markov decision process(MDP)problem is formulated.Subsequently,an improved double deep Q network(iDDQN)algorithm is proposed to enhance the exploration ability by modifying the calculation of the Q value,and a prioritized experience replay(PER)is introduced into the iDDQN to improve the training speed and effectiveness.Finally,taking advantage of the federated learning(FL)and iDDQN algorithms,a federated iDDQN is proposed to design an MEMG energy management strategy to enable each microgrid to share its experiences in the form of local neural network(NN)parameters with the federation layer,thus ensuring the privacy and security of data.The simulation results validate the superior performance of the proposed energy management strategy in minimizing the economic costs of the MEMG while reducing CO_2 emissions and protecting data privacy.
基金The Shandong Traditional Chinese Medicine Science and Technology Development Program 2020Q132。
文摘Objective:To investigate the clinical efficacy of acupuncture combined with emotional intervention in patients with post-stroke depression(PSD).Methods:A total of 100 patients with PSD who met the inclusion criteria were randomly divided into an experimental group(50 cases)and a control group(50 cases)using the random number table method,and the enrollment was in order of admission time.The control group used conventional treatment of oral antidepressant Deanxit tablets(0.5 mg flupenthixol+10 mg melitracen)with the dose appropriately adjusted according to the patient’s medication effect,and modern rehabilitation treatment given selectively according to the patient’s condition.The experimental group had similar treatment as the control group with the addition of traditional Chinese medicine(TCM)acupuncture combined with emotional intervention.The application effects of both groups before and after treatment were verified using the Hamilton Depression Rating Scale(Ham-D),National Institutes of Health Stroke Scale(NIHSS),and Activities of Daily Living(ADL),serotonin levels were measured,and statistical analyses were carried out.Results:The total effective rate of patients in the experimental group was significantly higher than that in the control group,and the Ham-D score,NIHSS score,ADL score,and serotonin level after treatment were significantly higher than those in the control group,and the difference between the two groups was statistically significant(P<0.05).Conclusion:For patients with PSD,adding TCM acupuncture with emotional intervention on top of conventional treatment significantly improve the clinical efficacy and better improve the daily life ability of patients.
基金supported by the National Natural Science Foundation of China,No. 30900155 and 81070496the Research Foundation of Education Bureau of Shaanxi Province,China,No. 09JK785+1 种基金Foundation of Interdisciplinary for Postgraduates from Northwest University,No. 08YJC22the Key Laboratory Funding of Northwestern University,Shaanxi Province in China
文摘Parthenogenetic embryonic stem cells have pluripotent differentiation potentials, akin to fertilized embryo-derived embryonic stem cells. The aim of this study was to compare the neuronal differentiation potential of parthenogenetic and fertilized embryo-derived embryonic stem cells. Before differentiation, karyotype analysis was performed, with normal karyotypes detected in both parthenogenetic and fertilized embryo-derived embryonic stem cells. Sex chromosomes were identified as XX. Immunocytochemistry and quantitative real-time PCR detected high expression of the pluripotent gene, Oct4, at both the mRNA and protein levels, indicating pluripotent differentiation potential of the two embryonic stem cell subtypes. Embryonic stern cells were induced with retinoic acid to form embryoid bodies, and then dispersed into single cells. Single cells were differentiated in N2 differentiation medium for 9 days. Immunocytochemistry showed parthenogenetic and fertilized embryo-derived embryonic stem cells both express the neuronal cell markers nestin, ~lll-tubulin and myelin basic protein. Quantitative real-time PCR found expression of neuregenesis related genes (Sox-1, Nestin, GABA, Pax6, Zic5 and Pitxl) in both types of embryonic stem cells, and Oct4 expression was significantly decreased. Nestin and Pax6 expression in parthenogenetic embryonic stem cells was significantly higher than that in fertilized embryo-derived embryonic stem cells. Thus, our experimental findings indicate that parthenogenetic embryonic stem cells have stronger neuronal differentiation potential than fertilized embryo-derived embryonic stem cells.
基金supported by the National Natural Science Foundation of China(No.52077146)the Sichuan Science and Technology Program(No.2023YFSY0032).
文摘In the competitive energy market,energy retailers are facing the uncertainties of both energy price and demand,which requires them to formulate reasonable energy purchasing and selling strategies for improving their competitiveness in this market.Particularly,the attractive multi-energy retail packages are the key for retailers to increase their benefit.Therefore,combined with incentive means and price signals,five types of multi-energy retail packages such as peak-valley time-of-use(TOU)price package and day-night bundled price package are designed in this paper for retailers.The iterative interactions between retailers and end-users are modeled using a bi-level model of stochastic optimization based on multi-leader multi-follower(MLMF)Stackelberg game,in which retailers are leaders and end-users are followers.Retailers make decisions to maximize the profit considering the conditional value at risk(CVaR)while end-users optimize the satisfaction of both energy comfort and economy.Besides,a distributed algorithm is proposed to obtain the Nash equilibrium of above MLMF Stackelberg game model while the particle swarm optimization(PSO)algorithm and CPLEX solver are applied to solve the optimization model for each participant(retailer or end-user).Numeral results show that the designed retail packages can increase the overall profit of retailers,and the overall satisfaction of industrial users is the highest while that of residential users is the lowest after game interaction.
基金the Ministry of Science and Technology of the People's Republic of China(No.2020YFF01014605).
文摘Objectives Benzimidazoles(BZs)are commonly used for the treatment of soil-transmitted helminth infections in veterinary clinics;however,misuse and overdosing of BZs will cause residual problems and have the potential to damage human health through the food chain.Thus,the existence of BZs in foods needs more attention.This study aims to establish a broad-spectrum immunoassay for rapid detection and to simultaneously monitor BZs in milk.Materials and Methods Based on structure analysis,a‘zero epitope loss’strategy,which introduced a spacer arm into the imino group of the imidazole ring of albendazole,was first adopted for hapten modification to obtain an ultra-sensitive and broad-spectrum antibody.An indirect competitive enzyme-linked immunosorbent assay(icELISA)was established for the detection of 18 BZs in milk sample with a single-step pretreatment.A quantitative structure–activity relationship model was constructed to interpret and predict the recognition.Results The antibody could recognize 20 BZs and the half-inhibitory concentrations ranged from 0.054 to 417.58 ng/mL,the limits of detection of icELISA ranged from 0.4 to 89.4 ng/mL,and the mean recovery rates ranged from 76.49%to 120.40%,with a coefficient of variation<20%.Substituent R1 of BZs was considered to be the main influencing factor for recognition,and the comparative molecular field analysis model(q2=0.724,r2=0.998)was finally chosen for further prediction.Conclusions The results indicated that the established icELISA could simultaneously identify 18 BZs,with good accuracy and precision,which was suitable for rapid detection of BZs in milk.
基金National Key Research and Development Program of China(2020YFA0908200)National Natural Science Foundation of China(81972150,82172428 and 61927805)+4 种基金Natural Science Foundation of Zhejiang(LR18H150001 and LQ22E030004)Shenzhen Fundamental Research Program(JCYJ20190813152616459)Key scientific and technological innovation projects of Wenzhou(ZY20200023)Wenzhou Innovation Team(Growth factor drug development)(No.201801)CAMS Innovation Fund for Medical Sciences(2019-I2M-5-028).
文摘Long-range peripheral nerve defect is a severe and worldwide disease.With the increasing development of tissue engineering,the excellent ability of nerve extracellular matrix(ECM)in peripheral nerve injury(PNI)has been widely studied and verified.Here,we present a novel microtube that contains gradient decellularized porcine sciatic nerve ECM hydrogel(pDScNM-gel)from microfluidics for sciatic nerve regeneration.The pDScNM is confirmed to enhance cell proliferation and migration,and improve the axon growth of primary dorsal root ganglions(DRGs)in a concentration-related manner.These behaviors were also achieved when cells were co-cultured in a gradient pDScNM microtube.The in vivo sciatic nerve regeneration and functional recovery were also demonstrated by assembling the gradient pDScNM microtubes with a medical silicon tube.These results indicated that the microtubes with gradient pDScNM could act as a promising alternative for repairing peripheral nerve defects and showed great potential in clinical use.
基金This work was financially supported by the National Science and Technology Major Project(Nos.2017-VⅠ-0003-0073 and 2017-Ⅶ-0008-0101).The authors are grateful to Prof.Yao Kefu and Miss.Liao Yang in Tsinghua University for the assistance and advice with the analysis of TEM results.
文摘Sliver is a common but easily neglected defect in single crystal Ni-based superalloy castings.To date,there is still no unified viewpoint on its formation mechanism and generation causes.In this work,the orientation discontinuity and motion behavior of sliver defects were studied through experiments and numerical simulations.The ultrathin wedge-shaped specimen containing the grain boundary of the sliver and the matrix was prepared at the initial position of the sliver defect for the observation of equal thick-ness fringes.The discontinuity of equal thickness fringes on both sides of the grain boundary was ob-served through a transmission electron microscope,which directly confirms the abrupt change in the orientation between the sliver and matrix from the nanoscale.The crystal lattices at the smooth area and the bulging area of the grain boundary were found to have unusually different arrangements.The irregular lattice arrangement at the bulging area shows that the grain boundary has experienced high-stress deformation.Statistical results of sliver orientation deviation with a further composition analysis show the micro protuberance of the mold shell has a noticeable inductive effect on the sliver generation.Furthermore,a self-developed three-dimensional phase-field simulation model coupled with the spatial topology algorithm is established to simulate the orientation deflection behavior and orientation devia-tion threshold of fractured dendrites.The simulation results indicated that there is an upper limit of the cross-section solid fraction at the fracture position for the motion of the fractured dendrites.When the cross-section solid fraction at the fracture position is higher than this upper limit,it will be difficult to produce large deviation slivers due to the structural limitation of surrounding dendrites.This upper limit does not change with the solidification temperature gradient.
基金financially supported by the National Natural Science Foundation of China (NSFC) under grant Nos.51401210 and 51271186
文摘Scanning speed is a critical parameter for laser process, which can play a key role in the microstruc- ture evolution of laser melting. In the laser melting of single crystal superalloy, the effects of scanning speed were investigated by experimental analysis and computational simulation. The laser was scanning along [710] direction on (001) surface in different speeds. Solidification microstructures of dendrites growth direction and the primary dendritic spacing were analyzed by metallograph. Besides, a planar interface during solidification was taken into attention, Experiment results indicated that the primary dendritic spacing and thickness of planar interface decrease with the increase of speed. Through simu- lation, distribution of dendrites growth velocity and thermal gradient along dendrite growth direction were calculated, and the simulation of dendrites growth direction agreed with the experiment results. Additionally, a constant value was acquired which can be used to predict the primary dendritic spacing. Moreover, according to curve-fitting method and inequality relation, a model was proposed to predict the thickness of planar interface.
基金the National Natural Science Foundation of China(Nos.51971214,51771191 and 51801206)the Aeronautics Power Foundation of China(No.DLJJ1825)。
文摘Fusion weld is a portable and economical joining and repairing method of metals.However,weld cracks often occur during the fusion weld of Ni-base superalloys,which hinder the applications of fusion weld on this kind of materials.In this work,the effects of microstructures of grain boundaries(GBs)of the prototype M951 superalloy on its weldability were investigated.The precipitated phases,the elemental segregations on GBs,and the morphologies of GBs can be largely altered by regulating the cooling rates of pre-weld heat treatments.With decreasing the cooling rate,chain-like M_(23)X_(6)phase precipitates along the GBs,accompanying segregations of B,and GBs becomes more serrated in morphology.During fusion weld,the engineered GBs in the M951 superalloy with a low cooling rate favor the formation of the continuous liquid films on GBs,which together with the serrated GB morphology significantly prevents the formation of weld cracks.Our findings imply that the weld-crack resistance of the superalloys can be ameliorated by engineering GBs.
基金the National Science and Technology Major Project(No.2017-VI-0002-0072)the National Key R&D Program of China(No.2017YFA0700704)+1 种基金the National Natural Science Foundation of China(Nos.51601192 and 51671188)the State Key Lab of Advanced Metals and Materials Open Fund(No.2018-Z07)。
文摘The effect of thermal exposure on microstructure and creep properties of a fourth-generation nickelbased single crystal superalloy was investigated.The thermal exposure of samples after the full heat treatment was carried out at 1000℃,1100℃ and 1140℃ for 100 h and 200 h.The γ’ coarsening,γ’ rafting and γ channel widening were observed in samples after thermal exposure.When the thermal exposure time was constant,the morphology of γ’ phase in the alloy evolved significantly with increasing aging temperature.The interracial dislocation networks in aged samples after creep ruptured gradually became irregular and sparse with the increase of exposure temperature.When the higher exposure temperature was used,enla rgement of the defect pores was observed in samples,the microcracks were more likely to initiate and propagate at the corner of these pores.After aging at 1000℃ for 100 h,the creep life at 1140℃/137 MPa was slightly longer than that of heat-treated sample,which could be attributed to the slightly coarsened γ’ phase,homogenization of refractor elements.In contrast,the creep life of sample exposed at 1140℃ for 100 h was greatly decreased.The decrease of creep life was dominated by the rafting of γ’phase,the irregular interfacial dislocation networks as well as the enlargement of homogenization pores.
基金supported by the National Natural Science Foundation of China(No.50901081)
文摘MCrAlY/TaC metal matrix composite coatings with 10, 20 and 30 wt.% TaC have been successfully produced by electrospark deposition (ESD). The effects of TaC content on microstructure, hardness and oxidation behavior of the composite coatings were studied. The results showed that the composite coatings were composed of superfine 9' columnar dendrite and large TaC particles dispersedly distributed. The hardness was enhanced but oxidation resistance of the composite coatings was reduced with increasing TaC contents.
基金supported by the Ministry of Industry and Information Technology through the National Science and Technology Major Project of China(No.2017-VI-0003-0073)。
文摘The detrimental effects of carbides and porosity on the fatigue crack initiation and propagation of nickel-based single-crystal superalloys have been reported by many previous studies.However,few studies have quantitatively compared the fatigue damaging effects of carbides and pores on the fatigue crack evolution.In this study,a high-resolution X-ray computed tomography(XCT)characterization of a DD5 nickel-based single-crystal superalloy during fatigue test was performed.The evolution of carbides,pores and cracks at all stages was observed and tracked.In order to quantify the 3D microstructures,a new damage factor that correlates the morphology of fracture surface with crack evolution behaviors was proposed.It was found that porosity was more detrimental than carbides in crack initiation and propagation during fatigue tests.Furthermore,pore spacing has been found to be the most significant factor among all controlling pore characteristics in the crack initiation stage and sphericity is the most critical pore characteristic in the crack propagation stage.Therefore,by statistically analyzing the evolution of carbides and pores during fatigue tests in this study,the underlying fatigue cracking mechanism of nickel-based superalloys is revealed.
基金financially supported by the National Science and Technology Major Project under(No.2017-Ⅵ-0002-0072)the National Key R&D Program of China(No.2017YFA0700704)+1 种基金the National Natural Science Foundation of China(Nos.51671188,51601192 and 51701210)the Youth Innovation Promotion Association,Chinese Academy of Sciences and State Key Lab of Advanced Metals and Materials Open Fund(No.2018-Z07)。
文摘Two alloys with different Ta and Al contents were applied to study the influence of Ta/Al ratio on the microstructural evolution and creep deformation under high temperature.The increase of Ta/Al ratio made theγ/γ'lattice misfit more negative and enhanced the volume fraction ofγ'phase,which produced cubic and smallγ'phase in the initial microstructures.These initial tinyγ'phases impeded the dislocations movement and delayed the course of complete raftedγ'phase during the origination of creep deformation,which prolonged the time of the primary creep stage.Moreover,the increase of Ta/Al ratio and addition of Ru produced the denser and stable dislocation networks,the high APB energy and better solution strengthening,which hindered the climbing and sliding of dislocations,and restrained the formation of superdislocations in theγ'precipitate.The second creep stage was extended,and the minimum creep rate was reduced.Hence,the increase of whole creep life of the alloy containing high Ta/Al ratio was attributed to the prolongation of the primary and second creep stages,and the low minimum creep rate.The appearance of the topological inversion phenomenon during the tertiary creep stage was the primary cause for the sudden increase of the creep strain rate of the alloy containing low Ta/Al ratio.However,the high creep strain rate of the alloy containing high Ta/Al ratio during the tertiary creep stage was related to the occurrence and extending of the cracks near the voids.Both alloys would lose efficacy within 20 h-30 h.
基金financially supported by the State Key Lab of Advanced Metals and Materials Open Fund under Grant No.2018-Z07the National Science and Technology Major Project under Grant No.2017-VI-0002-0072+2 种基金the National Key R&D Program of China under Grant No.2017YFA0700704the National Natural Science Foundation of China(NSFC)under Grant Nos.51601192,51671188the Youth Innovation Promotion Association,Chinese Academy of Sciences
文摘The application and component designs of single crystal superalloys are restricted by the precipitation of topologically closed packed(TCP)phases,which can deteriorate the microstructural stability of the alloys severely.Limited researches concerning the type and morphology evolution of TCP phases under elevated temperature conditions have been reported previously.In the present work,three Re-containing single crystal alloys were designed to investigate TCP phase evolution via long term isothermal exposure tests at 1120℃while the effects of Re on the microstructural characteristic and elements segregation were also clarified.The results showed that the addition of Re increased the instability of the alloys and the volume fraction of the TCP phases exceeded 5 vol%when the Re content reached 3 wt%.The increasing Re content had also raised the precipitation temperature of TCP phases but it did not change the type of them after long term aging;all the TCP particles were identified asμphase in this study.Moreover,the elements segregation became considerably serious as Re addition increased constantly,which brought about various morphologies of theμphase in the experimental alloys.In particular,the rod-like and needle-likeμphases demonstrated the typical orientation withinγmatrix while the blockyμphase was dispersedly distributed in the space.No specific orientation relationship could be observed in theμphase when the addition of Re exceeded certain threshold value.
基金supported by the Postdoctoral Science Foundation of China(No.20090460517)
文摘Nuclear envelope proteins have important roles in chromatin organization and signal-dependent transcriptional regulation. A previous study reported that the inner nuclear membrane protein, Otefin (Ote), was essential for germline stem cell (GSC) maintenance via interaction with Smad complex. The interaction of Ore with the Smad complex recruits the barn locus to the nuclear periphery and subsequently results in bam transcriptional silencing, revealing that nuclear peripheral localization is essential for barn gene regulation. However, it remains unknown whether the nuclear peripheral localization is sufficient for barn silencing. To address this issue, we have established a tethering system, in which the Gal4 DNA binding domain (DBD) of the Flag:Gal4 DBD:Ote△LEM fusion protein physically interacts with the Gal4 binding sites upstream of bamP-gfp to artificially recruit the reporter gene gfp to the nuclear membrane. Our data demonstrated that the nuclear peripheral localization seemed to affect the expression of the target naked gene in S2 ceils. By contrast, in Drosophila germ cells, the nuclear membrane localization was not sufficient for gene silencing.
基金the National Natural Science Foundation of China (Grant No. 11771213)the National Key Research and Development Project of China (Grant No. 2016YFC0600310)the Major Projects of Natural Sciences of University in Jiangsu Province of China (Grant No. 15KJA110002).
文摘This paper gives several structure-preserving schemes for the Degasperis-Procesi equation which has bi-Hamiltonian structures consisted of both complex and non-local Hamiltonian differential operators. For this sake, few structure-preserving schemes have been proposed so far. In our work, based on one of the bi-Hamiltonian structures, a symplectic scheme and two new energy-preserving schemes are constructed. The symplecticity comes straightly from the application of the implicit midpoint method on the semi-discrete system which is proved to remain Hamiltonian, while the energy conservation is derived by the combination of the averaged vector field method of second and fourth order, respectively. Some numerical results are presented to show that the three schemes do have the advantages in numerical stability, accuracy in long time computing and ability to preserve the invariants of the DP equation.
文摘In this paper,a tumor immune model with time delay is studied.First,the stability of nonnegative equilibria is analyzed.Then the time delay τ is selected as a bifurcation parameter and the existence of Hopf bifurcation is proved.Finally,by using the canonical method and the central manifold theory,the criteria for judging the direction and stability of Hopf bifurcation are given.
基金This work is supported by the Jiangsu Collaborative Innovation Center for Climate Change,the National Natural Science Foundation of China(Grant Nos.11271195 and 11271196)and the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘In this paper,we propose an explicit symplectic Fourier pseudospectral method for solving the Klein-Gordon-Schr odinger equation.The key idea is to rewrite the equation as an infinite-dimensional Hamiltonian system and discrete the system by using Fourier pseudospectral method in space and symplectic Euler method in time.After composing two different symplectic Euler methods for the ODEs resulted from semi-discretization in space,we get a new explicit scheme for the target equation which is of second order in space and spectral accuracy in time.The canonical Hamiltonian form of the resulted ODEs is presented and the new derived scheme is proved strictly to be symplectic.The new scheme is totally explicitwhereas symplectic scheme are generally implicit or semi-implicit.Linear stability analysis is carried and a necessary Courant-Friedrichs-Lewy condition is given.The numerical results are reported to test the accuracy and efficiency of the proposed method in long-term computing.