Bioprinting has been widely investigated for tissue engineering and regenerative medicine applications.However,it is still difficult to reconstruct the complex native cell arrangement due to the limited printing resol...Bioprinting has been widely investigated for tissue engineering and regenerative medicine applications.However,it is still difficult to reconstruct the complex native cell arrangement due to the limited printing resolution of conventional bioprinting techniques such as extrusion-and inkjet-based printing.Recently,an electrohydrodynamic(EHD)bioprinting strategy was reported for the precise deposition of well-organized cell-laden constructs with microscale filament size,whereas few studies have been devoted to developing bioinks that can be applied for EHD bioprinting and simultaneously support cell spreading.This study describes functionalized alginate-based bioinks for microscale EHD bioprinting using peptide grafting and fibrin incorporation,which leads to high cell viability(>90%)and cell spreading.The printed filaments can be further refined to as small as 30μm by incorporating polyoxyethylene and remained stable over one week when exposed to an aqueous environment.By utilizing the presented alginate-based bioinks,layer-specific cell alignment along the printing struts could be observed inside the EHD-printed microscale filaments,which allows fabricating living constructs with cell-scale filament resolution for guided cellular orientation.展开更多
We report the mineralogy and geochemistry of hydrothermal sulphide from the crater of a volcanic high near 18°36.4′S of the Central Lau Spreading Center.During 1990s,that volcanic structure was reported active a...We report the mineralogy and geochemistry of hydrothermal sulphide from the crater of a volcanic high near 18°36.4′S of the Central Lau Spreading Center.During 1990s,that volcanic structure was reported active and sulphide samples were collected by MIR submersible.A section of a chimney-like structure from the crater-floor was studied here.The Fe-depleted sphalerites,and Co-depleted pyrites in that chimney were similar to those commonly found in low to moderate temperature(<300℃)sulphides from sediment-starved hydrothermal systems.Bulk analyses of three parts of that chimney section showed substantial enrichment of Zn(18%–20%)and Fe(14%–27%)but depletion of Cu(0.8%–1.3%).In chondrite-normalized rare earth element-patterns,the significant negative Ce-anomalies(Ce/Ce*=0.27–0.39)and weakly positive Eu-anomalies(Eu/Eu*=1.60–1.68)suggested sulphide mineralisation took place from reduced low-temperature fluid.The depleted concentration of lithophiles in this sulphide indicates restricted contribution of sub-ducting plate in genesis of source fluid as compared to those from other parts of Lau Spreading Centre.Uniform mineralogy and bulk composition of subsamples across the chimney section suggests barely any alteration of fluid composition and/or mode of mineralisation occurred during its growth.展开更多
This paper is concerned with the spreading speed of a food-limited population model with delay.First,the existence of the solution of Cauchy problem is proved.Then,the spreading speed of solutions with compactly suppo...This paper is concerned with the spreading speed of a food-limited population model with delay.First,the existence of the solution of Cauchy problem is proved.Then,the spreading speed of solutions with compactly supported initial data is investigated by using the general Harnack inequality.Finally,we present some numerical simulations and investigate the dynamical behavior of the solution.展开更多
Copying,compiling,publishing,disseminating,and referencing anti-epidemic books of medical formularies were common activities during the outbreak of epidemics in the Qing dynasty.Its emergence,motivated by epidemic dis...Copying,compiling,publishing,disseminating,and referencing anti-epidemic books of medical formularies were common activities during the outbreak of epidemics in the Qing dynasty.Its emergence,motivated by epidemic disease again and again,was important component parts of epidemic prevention and control.They played a unique role as media on affairs such as treating patients suffering from infectious diseases,mobilizing peoples to make contributions to anti-epidemic activities,integrating and popularizing knowledge of epidemic prevention.Anti-epidemic books of medical formularies were important to link peoples,things,and substances related with epidemic prevention and control,and were a kind of motivation to actively deal with the infectious disease,control the epidemic,and maintain health.Compared to other common measures,anti-epidemic books of medical formularies participated in many prevention and control practices deeply,which actually built a low cost,spontaneous,dispersed and non-institutional system to respond to epidemic,and the system had characteristics of stronger conductibility,bigger coverage area,and better external benefits.展开更多
In this research,two shake table experiments were conducted to study the effects of non-liquefiable crust layer and superstructure mass on the responses of two sets of 22 pile groups to liquefactioninduced lateral spr...In this research,two shake table experiments were conducted to study the effects of non-liquefiable crust layer and superstructure mass on the responses of two sets of 22 pile groups to liquefactioninduced lateral spreading.In this regard,an inclined base layer overlain by a very loose liquefiable layer was constructed in both models;while only in one model,a non-liquefiable crust layer was built.A lumped mass,being representative of a superstructure,was attached to the cap of one pile group in both models.The models were fully instrumented with various sensors,including acceleration,displacement,and pore water pressure transducers.Also,the piles were instrumented with pair strain gauges to measure pure bending moments induced by cyclic and monotonic loadings associated with ground shaking and lateral spreading,respectively.The results showed that the existence of the non-liquefiable crust layer increases both the maximum and residual soil displacements at the free field and also the maximum bending moments in the piles.The results of the experiments indicated that the crust layer induces a high kinematic lateral soil pressure and force on the piles which are not present in the crustless case.The crust layer increases the pile cap displacement before liquefaction,albeit decreases it after liquefaction,due to the elastic rebound of the piles in the liquefiable layer.The crust layer postpones both liquefaction triggering and dissipation of excess pore water pressure.The existence of the superstructure mass on the pile caps decreases the acceleration amplitude of the pile caps,while increases their maximum displacement.展开更多
Lunar surface additive manufacturing with lunar regolith is a key step in in-situ resource utilization.The powder spreading process is the key process,which has a major impact on the quality of the powder bed and the ...Lunar surface additive manufacturing with lunar regolith is a key step in in-situ resource utilization.The powder spreading process is the key process,which has a major impact on the quality of the powder bed and the precision of molded parts.In this study,the discrete element method(DEM)was adopted to simulate the powder spreading process with a roller.The three powder bed quality indicators,including the molding layer offset,voidage fraction,and surface roughness,were established.Besides,the influence of the three process parameters,which are roller’s translational speed,rotational speed,and powder spreading layer thickness on the powder bed quality indicators was also analyzed.The results show that with the reduction of the powder spreading layer thickness and the increase of the rotational speed,the offset increased significantly;when the translational speed increased,the offset first increased and then decreased,which resulted in an extreme value;with the increase of the layer thickness and the decrease of the translational speed,the values for voidage fraction and surface roughness significantly reduced.The powder bed quality indicators were adopted as the optimization objective,and the multi-objective parameter optimization was carried out.The predicted optimal powder spreading parameters and powder bed quality indicators were then obtained.Moreover,the optimal values were then verified.This study can provide informative guidance for in-situ manufacturing at the moon in future deep space exploration missions.展开更多
The influence of the longitudinal acceleration and the angular acceleration of detecting target based on vortex electromagnetic waves in keyhole space are analyzed.The spectrum spreads of different orbital angular mom...The influence of the longitudinal acceleration and the angular acceleration of detecting target based on vortex electromagnetic waves in keyhole space are analyzed.The spectrum spreads of different orbital angular momentum(OAM)modes in different non-line-of-sight situations are simulated.The errors of target accelerations in detection are calculated and compared based on the OAM spectra spreading by using two combinations of composite OAM modes in the keyhole space.According to the research,the effects about spectrum spreads of higher OAM modes are more obvious.The error in detection is mainly affected by OAM spectrum spreading,which can be reduced by reasonably using different combinations of OAM modes in different practical situations.The above results provide a reference idea for investigating keyhole effect when vortex electromagnetic wave is used to detect accelerations.展开更多
In this note we study subplanes of order q of the projective plane Π=PG( 2, q 3 ) and the ruled varieties V 2 5 of Σ=PG( 6,q ) using the spatial representation of Π in Σ, by fixing a hyperplane Σ ′ with a regula...In this note we study subplanes of order q of the projective plane Π=PG( 2, q 3 ) and the ruled varieties V 2 5 of Σ=PG( 6,q ) using the spatial representation of Π in Σ, by fixing a hyperplane Σ ′ with a regular spread of planes. First are shown some configurations of the affine q-subplanes. Then to prove that a variety V 2 5 of Σ represents a non-affine subplane of order q of Π, after having shown basic incidence properties of it, such a variety V 2 5 is constructed by choosing appropriately the two directrix curves in two complementary subspaces of Σ. The result can be translated into further incidence properties of the affine points of V 2 5 . Then a maximal bundle of varieties V 2 5 having in common one directrix cubic curve is constructed.展开更多
Gabapentinoid drugs(pregabalin and gabapentin) have been successfully used in the treatment of neuro pathic pain and in focal seizure prevention.Recent research has demonstrated their potent activities in modulating n...Gabapentinoid drugs(pregabalin and gabapentin) have been successfully used in the treatment of neuro pathic pain and in focal seizure prevention.Recent research has demonstrated their potent activities in modulating neurotransmitter release in neuronal tissue,oxidative stress,and inflammation,which matches the mechanism of action via voltage-gated calcium channels.In this review,we briefly elaborate on the medicinal history and ligand-binding sites of gabapentinoids.We systematically summarize the preclinical and clinical research on gabapentinoids in stroke,including ischemic stro ke,intracerebral hemorrhage,subarachnoid hemorrhage,seizures after stro ke,cortical spreading depolarization after stroke,pain after stroke,and nerve regeneration after stro ke.This review also discusses the potential to rgets of gabapentinoids in stroke;however,the existing results are still unce rtain regarding the effect of gabapentinoids on stroke and related diseases.Further preclinical and clinical trials are needed to test the therapeutic potential of gabapentinoids in stroke.Therefore,gabapentinoids have both opportunities and challenges in the treatment of stroke.展开更多
This paper first estimated the infectious capacity of COVID-19 based on the time series evolution data of confirmed cases in multiple countries. Then, a method to infer the cross-regional spread speed of COVID-19 was ...This paper first estimated the infectious capacity of COVID-19 based on the time series evolution data of confirmed cases in multiple countries. Then, a method to infer the cross-regional spread speed of COVID-19 was introduced in this paper, which took the gross domestic product(GDP) of each region as one of the factors that affect the spread speed of COVID-19 and studied the relationship between the GDP and the infection density of each region(China's Mainland, the United States, and EU countries). In addition, the geographic distance between regions was also considered in this method and the effect of geographic distance on the spread speed of COVID-19 was studied. Studies have shown that the probability of mutual infection of these two regions decreases with increasing geographic distance. Therefore, this paper proposed an epidemic disease spread index based on GDP and geographic distance to quantify the spread speed of COVID-19 in a region. The analysis results showed a strong correlation between the epidemic disease spread index in a region and the number of confirmed cases. This finding provides reasonable suggestions for the control of epidemics. Strengthening the control measures in regions with higher epidemic disease spread index can effectively control the spread of epidemics.展开更多
Slow inward currents are known as neuronal excitatory currents mediated by glutamate release and activation of neuronal extra synaptic N-met hyl-D-aspartate receptors with the contribution of astrocytes.These events a...Slow inward currents are known as neuronal excitatory currents mediated by glutamate release and activation of neuronal extra synaptic N-met hyl-D-aspartate receptors with the contribution of astrocytes.These events are significantly slower than the excitatory postsynaptic currents.Parameters of slow inward currents are determined by seve ral factors including the mechanisms of astrocytic activation and glutamate release,as well as the diffusion pathways from the release site towards the extra synaptic recepto rs.Astrocytes are stimulated by neuronal network activity,which in turn excite neurons,forming an astrocyte-neuron feedback loop.Mostly as a consequence of brain edema,astrocytic swelling can also induce slow inward currents under pathological conditions.There is a growing body of evidence on the roles of slow inward currents on a single neuron or local network level.These events often occur in synchro ny on neurons located in the same astrocytic domain.Besides synchronization of neuronal excitability,slow inward currents also set synaptic strength via eliciting timing-dependent synaptic plasticity.In addition,slow inward currents are also subject to non-synaptic plasticity triggered by long-la sting stimulation of the excitatory inputs.Of note,there might be important regionspecific differences in the roles and actions triggering slow inward currents.In greater networks,the pathophysiological roles of slow inward currents can be better understood than physiological ones.Slow inward currents are identified in the pathophysiological background of autism,as slow inward currents drive early hypersynchrony of the neural networks.Slow inward currents are significant contributors to paroxysmal depolarizational shifts/interictal spikes.These events are related to epilepsy,but also found in Alzheimer's disease,Parkinson's disease,and stroke,leading to the decline of cognitive functions.Events with features overlapping with slow inward currents(excitatory,N-methyl-Daspartate-receptor mediated currents with astrocytic contribution) as ischemic currents and spreading depolarization also have a well-known pathophysiological role in worsening consequences of stroke,traumatic brain injury,or epilepsy.One might assume that slow inward currents occurring with low frequency under physiological conditions might contribute to synaptic plasticity and memory formation.However,to state this,more experimental evidence from greater neuronal networks or the level of the individual is needed.In this review,I aimed to summarize findings on slow inward currents and to speculate on the potential functions of it.展开更多
Two full-scale experiments using controlled blasting were conducted in the Port of Tokachi on Hokkaido Island,Japan, to assess the behavior of piles and pipelines subjected to lateral spreading. Test specimens were ex...Two full-scale experiments using controlled blasting were conducted in the Port of Tokachi on Hokkaido Island,Japan, to assess the behavior of piles and pipelines subjected to lateral spreading. Test specimens were extensively instrumented with strain gauges to measure the distribution of moment during lateral spreading. This allowed us to compute the loading condition, as well as to conduct damage and performance assessments on the piles and pipelines. This paper presents the test results and discussions on the response of single piles and pipelines observed from the full-scale experiments. Based on the test results, it can be concluded that using controlled blasting successfully liquefied the soil, and subsequently induced lateral spreading. The movements of the single pile, as well as the transverse pipelines, were approximately the same as the free field soil movement. Observed moment distribution of the single pile indicated that global translation of the liquefied soil layer provided insignificant force to the pile. In addition, the degree of fixity at the pile tip significantly affected the moment along the pile as well as the pile head displacement. The pile with a higher degree of fixity at the pile tip had smaller pile head displacement but larger maximum moment.展开更多
In this paper, we investigate the regularity of spreading of information and public opinions towards two competing products in complex networks. By building its mathematical model and simulating its evolution process,...In this paper, we investigate the regularity of spreading of information and public opinions towards two competing products in complex networks. By building its mathematical model and simulating its evolution process, we have found the statistical regularity for support rates of two different products at a steady stage. The research shows that strength of the public opinion spreading is proportional to the final support rates of a product.展开更多
With processing and interpretation of 25 000 km full-coverage multibeam swath data from the eastern South China Sea, it is found that NE-trending and NW-trending linear morphological featuressuch as scarps, horsts and...With processing and interpretation of 25 000 km full-coverage multibeam swath data from the eastern South China Sea, it is found that NE-trending and NW-trending linear morphological featuressuch as scarps, horsts and grabens, govem the central part (14°～ 17° N) of eastern subbasin.Compared with reflection seismic profiles, these NE-trending linear morpho-structures are considered to be the representation of basement structures on seabed and can be divided into three linear structural zones. The trend of the central zone is NE45°～50° occurring around extinct spreading center, the trend of the second zone is NE70°～78° on both sides of the central one and the trend of the third zone is about NE60° just on the north of the second one. These three NE-trending linear zones are formed in late-stage NW-SE-trending seafloor spreading of the eastern subbasin along NW-trending linear faults, and respectively correspond to three spreading episodes: 17.0～19.0 Ma (5d-5e), 19.0～21.0 Ma (5e-6a) and 21.0～24.2 Ma (6a-6c) based on the contrast of morpho-structures to magnetic lineation anomalies.展开更多
The reactive spread behaviour of Cu particles on the surJace of Al has been studied.The roleof oxide film and the .formation mechanism of the joint during Al/Cu contacting reactionbrazing have been discussed.
Neuroendocrine tumors of the gastrointestinal tract are rare neoplasms. Rectal neuroendocrine tumors consist approximately the 5%-14% of all neuroendocrine neoplasms in Europe. These tumors are diagnosed in relatively...Neuroendocrine tumors of the gastrointestinal tract are rare neoplasms. Rectal neuroendocrine tumors consist approximately the 5%-14% of all neuroendocrine neoplasms in Europe. These tumors are diagnosed in relatively young patients,with a mean age at diagnosis of 56 years. Distant metastases from rectal neuroendocrine tumors are not very common. Herein we describe a case of a rectal neuroendocrine tumor which metastasized to the lung,mediastinum and orbit. This case underscores the importance of early identification and optimal management to improve patient's prognosis. Therefore,the clinical significance of this case is the necessity of physicians' awareness and education regarding neuroendocrine tumors' diagnosis and management.展开更多
The stiffness spreading method (SSM) was initially proposed for layout optimization of truss structures,in which an artificial elastic material of low modulus is uniformly distributed in the design domain to create co...The stiffness spreading method (SSM) was initially proposed for layout optimization of truss structures,in which an artificial elastic material of low modulus is uniformly distributed in the design domain to create connections between discrete members.In this paper,a modified stiffness spreading method is proposed by replacing the artificial elastic material with auxiliary bars to connect real members of the truss structure.Since the background continuum mesh for the elastic material is no longer required,the computational cost is significantly reduced.Like SSM,the new method is advantageous in that an initial design may consist of disconnected bars allocated in the design domain,and mathematical programming methods can be applied for the efficient solution of the formulated optimization problem.A number of solution strategies are also developed to achieve more practical designs with lower computational cost.Numerical examples of both 2-D and 3-D truss structures are presented to demonstrate the feasibility,robustness and effectiveness of the proposed method.展开更多
The method of energy dispersion in magnetic field is used to analyze the energy spread of the triple-pulse electron beam generated by the Dragon-II linear induction accelerator.A sector magnet is applied for energy an...The method of energy dispersion in magnetic field is used to analyze the energy spread of the triple-pulse electron beam generated by the Dragon-II linear induction accelerator.A sector magnet is applied for energy analysis of the electron beam,with a bending radius of 300 mm and a deflection angle of 90°.For each pulse,the time-resolved and integral images of the electron position at the output port of beam-bending line are recorded by a streak camera and a CCD camera,respectively.Experimental results demonstrate an energy spread of less than ±2.0%for the electron pulses.The cavity voltage waveforms obtained by different detectors are also analyzed for comparison.展开更多
As mass transport mechanisms,the spreading and mixing(dilution) processes of miscible contaminated compounds are fundamental to understanding reactive transport behaviors and transverse dispersion.In this study,the sp...As mass transport mechanisms,the spreading and mixing(dilution) processes of miscible contaminated compounds are fundamental to understanding reactive transport behaviors and transverse dispersion.In this study,the spreading and dilution processes of a miscible contaminated compound in a three-dimensional self-affine rough fracture were simulated with the coupled lattice Boltzmann method(LBM).Moment analysis and the Shannon entropy(dilution index) were employed to analyze the spreading and mixing processes,respectively.The corresponding results showed that the spreading process was anisotropic due to the heterogeneous aperture distribution.A compound was transported faster in a large aperture region than in a small aperture region due to the occurrence of preferential flow.Both the spreading and mixing processes were highly dependent on the fluid flow velocity and molecular diffusion.The calculated results of the dilution index showed that increasing the fluid flow velocity and molecular diffusion coefficient led to a higher increasing rate of the dilution index.展开更多
基金This work was financially supported by the National Key Research and Development Program of China(No.2018YFA0703003)the National Natural Science Foundation of China(No.52125501)+1 种基金the Key Research Project of Shaanxi Province(Nos.2021LLRH-08,2020GXLH-Y-021,and 2021GXLH-Z-028)the Youth InnovationTeam of Shaanxi Universities and the Fundamental Research Funds for the Central Universities.
文摘Bioprinting has been widely investigated for tissue engineering and regenerative medicine applications.However,it is still difficult to reconstruct the complex native cell arrangement due to the limited printing resolution of conventional bioprinting techniques such as extrusion-and inkjet-based printing.Recently,an electrohydrodynamic(EHD)bioprinting strategy was reported for the precise deposition of well-organized cell-laden constructs with microscale filament size,whereas few studies have been devoted to developing bioinks that can be applied for EHD bioprinting and simultaneously support cell spreading.This study describes functionalized alginate-based bioinks for microscale EHD bioprinting using peptide grafting and fibrin incorporation,which leads to high cell viability(>90%)and cell spreading.The printed filaments can be further refined to as small as 30μm by incorporating polyoxyethylene and remained stable over one week when exposed to an aqueous environment.By utilizing the presented alginate-based bioinks,layer-specific cell alignment along the printing struts could be observed inside the EHD-printed microscale filaments,which allows fabricating living constructs with cell-scale filament resolution for guided cellular orientation.
文摘We report the mineralogy and geochemistry of hydrothermal sulphide from the crater of a volcanic high near 18°36.4′S of the Central Lau Spreading Center.During 1990s,that volcanic structure was reported active and sulphide samples were collected by MIR submersible.A section of a chimney-like structure from the crater-floor was studied here.The Fe-depleted sphalerites,and Co-depleted pyrites in that chimney were similar to those commonly found in low to moderate temperature(<300℃)sulphides from sediment-starved hydrothermal systems.Bulk analyses of three parts of that chimney section showed substantial enrichment of Zn(18%–20%)and Fe(14%–27%)but depletion of Cu(0.8%–1.3%).In chondrite-normalized rare earth element-patterns,the significant negative Ce-anomalies(Ce/Ce*=0.27–0.39)and weakly positive Eu-anomalies(Eu/Eu*=1.60–1.68)suggested sulphide mineralisation took place from reduced low-temperature fluid.The depleted concentration of lithophiles in this sulphide indicates restricted contribution of sub-ducting plate in genesis of source fluid as compared to those from other parts of Lau Spreading Centre.Uniform mineralogy and bulk composition of subsamples across the chimney section suggests barely any alteration of fluid composition and/or mode of mineralisation occurred during its growth.
基金Supported by the National Natural Science Foundation of China(11371179)。
文摘This paper is concerned with the spreading speed of a food-limited population model with delay.First,the existence of the solution of Cauchy problem is proved.Then,the spreading speed of solutions with compactly supported initial data is investigated by using the general Harnack inequality.Finally,we present some numerical simulations and investigate the dynamical behavior of the solution.
基金financed by the grant from the National Social Science Fund of China(No.18ZDA175)Youth Fund for Humanities and Social Sciences Research of the Ministry of Education(No.20YJC770021)。
文摘Copying,compiling,publishing,disseminating,and referencing anti-epidemic books of medical formularies were common activities during the outbreak of epidemics in the Qing dynasty.Its emergence,motivated by epidemic disease again and again,was important component parts of epidemic prevention and control.They played a unique role as media on affairs such as treating patients suffering from infectious diseases,mobilizing peoples to make contributions to anti-epidemic activities,integrating and popularizing knowledge of epidemic prevention.Anti-epidemic books of medical formularies were important to link peoples,things,and substances related with epidemic prevention and control,and were a kind of motivation to actively deal with the infectious disease,control the epidemic,and maintain health.Compared to other common measures,anti-epidemic books of medical formularies participated in many prevention and control practices deeply,which actually built a low cost,spontaneous,dispersed and non-institutional system to respond to epidemic,and the system had characteristics of stronger conductibility,bigger coverage area,and better external benefits.
基金support by the Construction and Development of Transportation Infrastructures Company affiliated with the Ministry of Roads and Urban Development of Iran and partial financial support granted by the Research Deputy of the Sharif University of Technology are acknowledged.
文摘In this research,two shake table experiments were conducted to study the effects of non-liquefiable crust layer and superstructure mass on the responses of two sets of 22 pile groups to liquefactioninduced lateral spreading.In this regard,an inclined base layer overlain by a very loose liquefiable layer was constructed in both models;while only in one model,a non-liquefiable crust layer was built.A lumped mass,being representative of a superstructure,was attached to the cap of one pile group in both models.The models were fully instrumented with various sensors,including acceleration,displacement,and pore water pressure transducers.Also,the piles were instrumented with pair strain gauges to measure pure bending moments induced by cyclic and monotonic loadings associated with ground shaking and lateral spreading,respectively.The results showed that the existence of the non-liquefiable crust layer increases both the maximum and residual soil displacements at the free field and also the maximum bending moments in the piles.The results of the experiments indicated that the crust layer induces a high kinematic lateral soil pressure and force on the piles which are not present in the crustless case.The crust layer increases the pile cap displacement before liquefaction,albeit decreases it after liquefaction,due to the elastic rebound of the piles in the liquefiable layer.The crust layer postpones both liquefaction triggering and dissipation of excess pore water pressure.The existence of the superstructure mass on the pile caps decreases the acceleration amplitude of the pile caps,while increases their maximum displacement.
文摘Lunar surface additive manufacturing with lunar regolith is a key step in in-situ resource utilization.The powder spreading process is the key process,which has a major impact on the quality of the powder bed and the precision of molded parts.In this study,the discrete element method(DEM)was adopted to simulate the powder spreading process with a roller.The three powder bed quality indicators,including the molding layer offset,voidage fraction,and surface roughness,were established.Besides,the influence of the three process parameters,which are roller’s translational speed,rotational speed,and powder spreading layer thickness on the powder bed quality indicators was also analyzed.The results show that with the reduction of the powder spreading layer thickness and the increase of the rotational speed,the offset increased significantly;when the translational speed increased,the offset first increased and then decreased,which resulted in an extreme value;with the increase of the layer thickness and the decrease of the translational speed,the values for voidage fraction and surface roughness significantly reduced.The powder bed quality indicators were adopted as the optimization objective,and the multi-objective parameter optimization was carried out.The predicted optimal powder spreading parameters and powder bed quality indicators were then obtained.Moreover,the optimal values were then verified.This study can provide informative guidance for in-situ manufacturing at the moon in future deep space exploration missions.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11804073 and 61775050).
文摘The influence of the longitudinal acceleration and the angular acceleration of detecting target based on vortex electromagnetic waves in keyhole space are analyzed.The spectrum spreads of different orbital angular momentum(OAM)modes in different non-line-of-sight situations are simulated.The errors of target accelerations in detection are calculated and compared based on the OAM spectra spreading by using two combinations of composite OAM modes in the keyhole space.According to the research,the effects about spectrum spreads of higher OAM modes are more obvious.The error in detection is mainly affected by OAM spectrum spreading,which can be reduced by reasonably using different combinations of OAM modes in different practical situations.The above results provide a reference idea for investigating keyhole effect when vortex electromagnetic wave is used to detect accelerations.
文摘In this note we study subplanes of order q of the projective plane Π=PG( 2, q 3 ) and the ruled varieties V 2 5 of Σ=PG( 6,q ) using the spatial representation of Π in Σ, by fixing a hyperplane Σ ′ with a regular spread of planes. First are shown some configurations of the affine q-subplanes. Then to prove that a variety V 2 5 of Σ represents a non-affine subplane of order q of Π, after having shown basic incidence properties of it, such a variety V 2 5 is constructed by choosing appropriately the two directrix curves in two complementary subspaces of Σ. The result can be translated into further incidence properties of the affine points of V 2 5 . Then a maximal bundle of varieties V 2 5 having in common one directrix cubic curve is constructed.
基金supported by the National Key R&D Program of China,No.2020YFC2008302the National Natural Science Foundation of China,No.81673631the Science and Technology Program of Sichuan Province,No.2020YFH0059 (all to YL)。
文摘Gabapentinoid drugs(pregabalin and gabapentin) have been successfully used in the treatment of neuro pathic pain and in focal seizure prevention.Recent research has demonstrated their potent activities in modulating neurotransmitter release in neuronal tissue,oxidative stress,and inflammation,which matches the mechanism of action via voltage-gated calcium channels.In this review,we briefly elaborate on the medicinal history and ligand-binding sites of gabapentinoids.We systematically summarize the preclinical and clinical research on gabapentinoids in stroke,including ischemic stro ke,intracerebral hemorrhage,subarachnoid hemorrhage,seizures after stro ke,cortical spreading depolarization after stroke,pain after stroke,and nerve regeneration after stro ke.This review also discusses the potential to rgets of gabapentinoids in stroke;however,the existing results are still unce rtain regarding the effect of gabapentinoids on stroke and related diseases.Further preclinical and clinical trials are needed to test the therapeutic potential of gabapentinoids in stroke.Therefore,gabapentinoids have both opportunities and challenges in the treatment of stroke.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.62266030 and 61863025)International S & T Cooperation Projects of Gansu province (Grant No.144WCGA166)Longyuan Young Innovation Talents and the Doctoral Foundation of LUT。
文摘This paper first estimated the infectious capacity of COVID-19 based on the time series evolution data of confirmed cases in multiple countries. Then, a method to infer the cross-regional spread speed of COVID-19 was introduced in this paper, which took the gross domestic product(GDP) of each region as one of the factors that affect the spread speed of COVID-19 and studied the relationship between the GDP and the infection density of each region(China's Mainland, the United States, and EU countries). In addition, the geographic distance between regions was also considered in this method and the effect of geographic distance on the spread speed of COVID-19 was studied. Studies have shown that the probability of mutual infection of these two regions decreases with increasing geographic distance. Therefore, this paper proposed an epidemic disease spread index based on GDP and geographic distance to quantify the spread speed of COVID-19 in a region. The analysis results showed a strong correlation between the epidemic disease spread index in a region and the number of confirmed cases. This finding provides reasonable suggestions for the control of epidemics. Strengthening the control measures in regions with higher epidemic disease spread index can effectively control the spread of epidemics.
基金funded by the National Research Developm ent and Innovation Office (NKFIH-K1468 73) (to BP)。
文摘Slow inward currents are known as neuronal excitatory currents mediated by glutamate release and activation of neuronal extra synaptic N-met hyl-D-aspartate receptors with the contribution of astrocytes.These events are significantly slower than the excitatory postsynaptic currents.Parameters of slow inward currents are determined by seve ral factors including the mechanisms of astrocytic activation and glutamate release,as well as the diffusion pathways from the release site towards the extra synaptic recepto rs.Astrocytes are stimulated by neuronal network activity,which in turn excite neurons,forming an astrocyte-neuron feedback loop.Mostly as a consequence of brain edema,astrocytic swelling can also induce slow inward currents under pathological conditions.There is a growing body of evidence on the roles of slow inward currents on a single neuron or local network level.These events often occur in synchro ny on neurons located in the same astrocytic domain.Besides synchronization of neuronal excitability,slow inward currents also set synaptic strength via eliciting timing-dependent synaptic plasticity.In addition,slow inward currents are also subject to non-synaptic plasticity triggered by long-la sting stimulation of the excitatory inputs.Of note,there might be important regionspecific differences in the roles and actions triggering slow inward currents.In greater networks,the pathophysiological roles of slow inward currents can be better understood than physiological ones.Slow inward currents are identified in the pathophysiological background of autism,as slow inward currents drive early hypersynchrony of the neural networks.Slow inward currents are significant contributors to paroxysmal depolarizational shifts/interictal spikes.These events are related to epilepsy,but also found in Alzheimer's disease,Parkinson's disease,and stroke,leading to the decline of cognitive functions.Events with features overlapping with slow inward currents(excitatory,N-methyl-Daspartate-receptor mediated currents with astrocytic contribution) as ischemic currents and spreading depolarization also have a well-known pathophysiological role in worsening consequences of stroke,traumatic brain injury,or epilepsy.One might assume that slow inward currents occurring with low frequency under physiological conditions might contribute to synaptic plasticity and memory formation.However,to state this,more experimental evidence from greater neuronal networks or the level of the individual is needed.In this review,I aimed to summarize findings on slow inward currents and to speculate on the potential functions of it.
文摘Two full-scale experiments using controlled blasting were conducted in the Port of Tokachi on Hokkaido Island,Japan, to assess the behavior of piles and pipelines subjected to lateral spreading. Test specimens were extensively instrumented with strain gauges to measure the distribution of moment during lateral spreading. This allowed us to compute the loading condition, as well as to conduct damage and performance assessments on the piles and pipelines. This paper presents the test results and discussions on the response of single piles and pipelines observed from the full-scale experiments. Based on the test results, it can be concluded that using controlled blasting successfully liquefied the soil, and subsequently induced lateral spreading. The movements of the single pile, as well as the transverse pipelines, were approximately the same as the free field soil movement. Observed moment distribution of the single pile indicated that global translation of the liquefied soil layer provided insignificant force to the pile. In addition, the degree of fixity at the pile tip significantly affected the moment along the pile as well as the pile head displacement. The pile with a higher degree of fixity at the pile tip had smaller pile head displacement but larger maximum moment.
文摘In this paper, we investigate the regularity of spreading of information and public opinions towards two competing products in complex networks. By building its mathematical model and simulating its evolution process, we have found the statistical regularity for support rates of two different products at a steady stage. The research shows that strength of the public opinion spreading is proportional to the final support rates of a product.
基金This study was supported by the National Major Fundamental Research Development Project of China under contract No. G2000046704.
文摘With processing and interpretation of 25 000 km full-coverage multibeam swath data from the eastern South China Sea, it is found that NE-trending and NW-trending linear morphological featuressuch as scarps, horsts and grabens, govem the central part (14°～ 17° N) of eastern subbasin.Compared with reflection seismic profiles, these NE-trending linear morpho-structures are considered to be the representation of basement structures on seabed and can be divided into three linear structural zones. The trend of the central zone is NE45°～50° occurring around extinct spreading center, the trend of the second zone is NE70°～78° on both sides of the central one and the trend of the third zone is about NE60° just on the north of the second one. These three NE-trending linear zones are formed in late-stage NW-SE-trending seafloor spreading of the eastern subbasin along NW-trending linear faults, and respectively correspond to three spreading episodes: 17.0～19.0 Ma (5d-5e), 19.0～21.0 Ma (5e-6a) and 21.0～24.2 Ma (6a-6c) based on the contrast of morpho-structures to magnetic lineation anomalies.
文摘The reactive spread behaviour of Cu particles on the surJace of Al has been studied.The roleof oxide film and the .formation mechanism of the joint during Al/Cu contacting reactionbrazing have been discussed.
文摘Neuroendocrine tumors of the gastrointestinal tract are rare neoplasms. Rectal neuroendocrine tumors consist approximately the 5%-14% of all neuroendocrine neoplasms in Europe. These tumors are diagnosed in relatively young patients,with a mean age at diagnosis of 56 years. Distant metastases from rectal neuroendocrine tumors are not very common. Herein we describe a case of a rectal neuroendocrine tumor which metastasized to the lung,mediastinum and orbit. This case underscores the importance of early identification and optimal management to improve patient's prognosis. Therefore,the clinical significance of this case is the necessity of physicians' awareness and education regarding neuroendocrine tumors' diagnosis and management.
基金The authors gratefully acknowledge the financial support provided by the National Science and Technology Major Project of the Ministry of Science and Technology of China(Grant 2016YFB0200605)the National Natural Science Foundation of China(Grant 11372004).
文摘The stiffness spreading method (SSM) was initially proposed for layout optimization of truss structures,in which an artificial elastic material of low modulus is uniformly distributed in the design domain to create connections between discrete members.In this paper,a modified stiffness spreading method is proposed by replacing the artificial elastic material with auxiliary bars to connect real members of the truss structure.Since the background continuum mesh for the elastic material is no longer required,the computational cost is significantly reduced.Like SSM,the new method is advantageous in that an initial design may consist of disconnected bars allocated in the design domain,and mathematical programming methods can be applied for the efficient solution of the formulated optimization problem.A number of solution strategies are also developed to achieve more practical designs with lower computational cost.Numerical examples of both 2-D and 3-D truss structures are presented to demonstrate the feasibility,robustness and effectiveness of the proposed method.
文摘The method of energy dispersion in magnetic field is used to analyze the energy spread of the triple-pulse electron beam generated by the Dragon-II linear induction accelerator.A sector magnet is applied for energy analysis of the electron beam,with a bending radius of 300 mm and a deflection angle of 90°.For each pulse,the time-resolved and integral images of the electron position at the output port of beam-bending line are recorded by a streak camera and a CCD camera,respectively.Experimental results demonstrate an energy spread of less than ±2.0%for the electron pulses.The cavity voltage waveforms obtained by different detectors are also analyzed for comparison.
基金supported by the National Natural Science Foundation of China(Grant No.41602239)the Natural Science Foundation of Jiangsu Province(Grant No.BK20160861)+2 种基金the Fundamental Research Funds for the Central Universities(Grant No.2016B05514)the International Postdoctoral Exchange Fellowship Program from the Office of China Postdoctoral Council(Grant No.20150048)the"333 Project"of Jiangsu Province(Grant No.BRA2015305)
文摘As mass transport mechanisms,the spreading and mixing(dilution) processes of miscible contaminated compounds are fundamental to understanding reactive transport behaviors and transverse dispersion.In this study,the spreading and dilution processes of a miscible contaminated compound in a three-dimensional self-affine rough fracture were simulated with the coupled lattice Boltzmann method(LBM).Moment analysis and the Shannon entropy(dilution index) were employed to analyze the spreading and mixing processes,respectively.The corresponding results showed that the spreading process was anisotropic due to the heterogeneous aperture distribution.A compound was transported faster in a large aperture region than in a small aperture region due to the occurrence of preferential flow.Both the spreading and mixing processes were highly dependent on the fluid flow velocity and molecular diffusion.The calculated results of the dilution index showed that increasing the fluid flow velocity and molecular diffusion coefficient led to a higher increasing rate of the dilution index.
