Li-rich layered oxide(LRLO)cathodes have been regarded as promising candidates for next-generation Li-ion batteries due to their exceptionally high energy density,which combines cationic and anionic redox activities.H...Li-rich layered oxide(LRLO)cathodes have been regarded as promising candidates for next-generation Li-ion batteries due to their exceptionally high energy density,which combines cationic and anionic redox activities.However,continuous voltage decay during cycling remains the primary obstacle for practical applications,which has yet to be fundamentally addressed.It is widely acknowledged that voltage decay originates from the irreversible migration of transition metal ions,which usually further exacerbates structural evolution and aggravates the irreversible oxygen redox reactions.Recently,constructing O2-type structure has been considered one of the most promising approaches for inhibiting voltage decay.In this review,the relationship between voltage decay and structural evolution is systematically elucidated.Strategies to suppress voltage decay are systematically summarized.Additionally,the design of O2-type structure and the corresponding mechanism of suppressing voltage decay are comprehensively discussed.Unfortunately,the reported O2-type LRLO cathodes still exhibit partially disordered structure with extended cycles.Herein,the factors that may cause the irreversible transition metal migrations in O2-type LRLO materials are also explored,while the perspectives and challenges for designing high-performance O2-type LRLO cathodes without voltage decay are proposed.展开更多
Fluid lubricated bearings have been widely adopted as support components for high-end equipment in metrology,semiconductor devices,aviation,strategic defense,ultraprecision manufacturing,medical treatment,and power ge...Fluid lubricated bearings have been widely adopted as support components for high-end equipment in metrology,semiconductor devices,aviation,strategic defense,ultraprecision manufacturing,medical treatment,and power generation.In all these applications,the equipment must deliver extreme working performances such as ultraprecise movement,ultrahigh rotation speed,ultraheavy bearing loads,ultrahigh environmental temperatures,strong radiation resistance,and high vacuum operation,which have challenged the design and optimization of reliable fluid lubricated bearings.Breakthrough of any related bottlenecks will promote the development course of high-end equipment.To promote the advancement of high-end equipment,this paper reviews the design and optimization of fluid lubricated bearings operated at typical extreme working performances,targeting the realization of extreme working performances,current challenges and solutions,underlying deficiencies,and promising developmental directions.This paper can guide the selection of suitable fluid lubricated bearings and optimize their structures to meet their required working performances.展开更多
The carbothermic reduction of vanadium titanomagnetite concentrate(VTC)with the assistance of Na_(2)CO_(3)was conducted in an argon atmosphere between 1073 and 1473 K.X-ray diffraction and scanning electron microscopy...The carbothermic reduction of vanadium titanomagnetite concentrate(VTC)with the assistance of Na_(2)CO_(3)was conducted in an argon atmosphere between 1073 and 1473 K.X-ray diffraction and scanning electron microscopy were used to investigate the phase transformations during the reaction.By investigating the reaction between VTC and Na_(2)CO_(3),it was concluded that molten Na_(2)CO_(3)broke the structure of titanomagnetite by combining with the acidic oxides(Fe_(2)O_(3),TiO_(2),Al_(2)O_(3),and SiO_(2))to form a Na-rich melt and release FeO and MgO.Therefore,Na_(2)CO_(3)accelerated the reduction rate.In addition,adding Na_(2)CO_(3)also benefited the agglomeration of iron particles and the slag–metal separation by decreasing the viscosity of the slag.Thus,Na_(2)CO_(3)assisted carbothermic reduction is a promising method for treating VTC at low temperatures.展开更多
BACKGROUND： Rifampicin inhibits the formation of a-synuclein multimer and protects against 1-methyl-4-phenyl-1,2, 3, 6-tetrahydropyritine （MPTP）-induced PC12 cell apoptosis. OBJECTIVE： To compare the effect of rif...BACKGROUND： Rifampicin inhibits the formation of a-synuclein multimer and protects against 1-methyl-4-phenyl-1,2, 3, 6-tetrahydropyritine （MPTP）-induced PC12 cell apoptosis. OBJECTIVE： To compare the effect of rifampicin pre- and post-treatment on tyrosine hydroxylase and α-synuclein expression in substantia nigra pars compacta in a rat model of Parkinson＇s disease. DESIGN, TIME AND SE＇B＇ING： A randomized, controlled experiment was performed at the Experimental Animal Center of Sun Yat-sen University North Campus （China） from November 2006 to October 2008. MATERIALS： Rifampicin was purchased from MD, USA; rotenone was purchased from Sigma, USA; mouse anti-rat α-synuclein monoclonal antibody was purchased from B＆D, USA; and rabbit anti-rat tyrosine hydroxylase monoclonal antibody was purchased from Chemicon, USA. METHODS： A total of 72 male, Sprague Dawley rats, aged 8 weeks, were randomly assigned to 5 groups： blank control （n = 12）, rifampicin （n = 12）, rotenone （n = 16）, rifampicin pre-treatment （n = 16）, and rifampicin post-treatment （n = 16）. Parkinson＇s disease model rats were established via a subcutaneous injection of rotenone （1.5 mg/kg per day） in the three treatment groups, once a day for 3 successive weeks. Rifampicin （30 mg/kg per day） was intragastrically administered in the rifampicin pre-treatment group 3 days prior to rotenone induction and in the rifampicin post-treatment group 7 days after rotenone induction. Rats were treated with a subcutaneous injection of 1 mL/kg per day sunflower oil in the blank control group and an intragastric injection of 30 mg/kg per day rifampicin in the rifampicin group, once a day for 3 successive weeks in total. MAIN OUTCOME MEASURES： Prior to treatment and in the end of the 3^rd week after treatment, the rats were evaluated using the modified neurological severity score. The substantia nigra from the rats was extracted for hematoxylin-eosin staining. Western blot analysis was performed to determine tyrosine hydroxylase and α-synuclein expression. RESULTS： Hematoxylin-eosin staining revealed a significant reduction in the number of substantia nigral neurons in the rotenone group, in addition to neurodegradation, hypopigmentation, and pyknosis. In the rifampicin pre-treatment and post-treatment groups, the number of dopaminergic neurons was significantly increased compared with the rotenone group （P 〈 0.01）, with slight neuronal damage. Compared with the rotenone group, substantia nigral tyrosine hydroxylase expression was significantly increased in the rifampicin pre-treatment and post-treatment groups （P 〈 0.01）, but α-synuclein expression and modified neurological severity scores were significantly decreased （P 〈 0.01）. In addition, the effect of rifampicin in the pre-treatment group was superior to the post-treatment group. There was no significant difference in tyrosine hydroxylase and α-synuclein expression, or in the modified neurological severity scores, between the blank control and rifampicin groups （P 〉 0.05）. CONCLUSION： Rifampicin significantly attenuated neuropathological and behavioral motor deficits induced by rotenone. Moreover, rifampicin enhanced tyrosine hydroxylase expression, but inhibited α-synuclein expression. The effect of rifampicin pre-treatment was superior to rifampicin post-treatment.展开更多
By using the momentum theorem and waterbalance principle, basic equations of slope runoff were derived, soil erosion by raindrop splash and runoff were discussed and a model was established for decribing hillslope soi...By using the momentum theorem and waterbalance principle, basic equations of slope runoff were derived, soil erosion by raindrop splash and runoff were discussed and a model was established for decribing hillslope soil erosion processes. The numerical solution of the model was obtained by adopting the Preissmann format and considering the common solution-determining conditions, from which not only the runoff and soil erosion but also their processes can be described. The model was validated by ten groups of observation data of Soil Conservation Ecological Science and Technology Demonstration Park of Jiangxi Province. Comparisons show that the maximum relative error between simulation and experimental data is about 10.98% for total runoff and 15 % for total erosion, 5.2% for runoffprocess and 6.1% for erosion process, indicating that the model is conceptually realistic and reliable and offers a feasible approach for further studies on the soil erosion process.展开更多
ZrC and ZrB2 are both typical ultra-high temperature ceramics,which can be used in the hyperthermal environment.In this study,a method for preparing ultrafine ZrC-ZrB2 composite powder was provided,by using the raw ma...ZrC and ZrB2 are both typical ultra-high temperature ceramics,which can be used in the hyperthermal environment.In this study,a method for preparing ultrafine ZrC-ZrB2 composite powder was provided,by using the raw materials of nano ZrO2,carbon black,B4C,and metallic Ca.It is worth pointing out that ZrC-ZrB2 composite powder with any proportion of ZrC to ZrB2 could be synthesized by this method.Firstly,a mixture of ZrC and C was prepared by carbothermal reduction of ZrO2.By adjusting the addition amount of B4C,ZrC was boronized by B4C to generate ZrC-ZrB2 composite powder with different compositions.Using this method,five composite powders with different molar ratios of ZrC and ZrB2(100ZrC,75ZrC-25ZrB2,50ZrC-50ZrB2,25ZrC-75ZrB2,and 100ZrB2)were prepared.When the temperature of boronization and decarburization process was 1473 K,the particle size of product was only tens of nanometres.Finally,the oxidation charac-teristics of different composite powders were investigated through oxidation experiments.The oxidation resistance of ZrC-ZrB2 composite powder continued to increase as the content of ZrB2 increased.展开更多
Our research was designed to explore the more effective rescuing treatment by summarizing clinical features of the patients with myasthenia gravis crisis. During the course, we carried out a retrospective analysis abo...Our research was designed to explore the more effective rescuing treatment by summarizing clinical features of the patients with myasthenia gravis crisis. During the course, we carried out a retrospective analysis about clinical data and the course of diagnose and treatment of 38 patients (65 cases) with myasthenia gravis crisis who were in hospital in recent 15 years. As a result, most patients with myasthenia gravis crisis relieved after positive treatment and the mortality was 3.1%. Among lots of treatments, incision of trachea earlier, hormonal therapy, dry treatment and to unite these three treatments were more effective than other treatments. The effective ratio was 100%. In the end, we concluded that to unite incision of trachea, immunosuppressive treatment and dry treatment reasonably can increase the effective ratio of rescuing myasthenia gravis crisis and improve the prognosis of patients obviously.展开更多
The environmental stability of infectious viruses in the laboratory setting is crucial to the transmission potential of human respiratory viruses.Different experimental techniques or conditions used in studies over th...The environmental stability of infectious viruses in the laboratory setting is crucial to the transmission potential of human respiratory viruses.Different experimental techniques or conditions used in studies over the past decades have led to diverse understandings and predictions for the stability of viral infectivity in the atmospheric environment.In this paper,we review the current knowledge on the effect of simulated atmospheric conditions on the infectivity of respiratory viruses,mainly focusing on influenza viruses and coronaviruses,including severe acute respiratory syndrome coronavirus 2 and Middle East respiratory syndrome coronavirus.First,we summarize the impact of the experimental conditions on viral stability;these involve the methods of viral aerosol generation,storage during aging and collection,the virus types and strains,the suspension matrixes,the initial inoculum volumes and concentrations,and the drying process.Second,we summarize and discuss the detection methods of viral infectivity and their disadvantages.Finally,we integrate the results from the reviewed studies to obtain an overall understanding of the effects of atmospheric environmental conditions on the decay of infectious viruses,especially aerosolized viruses.Overall,this review highlights the knowledge gaps in predicting the ability of viruses to maintain infectivity during airborne transmission.展开更多
Tunnel seismic advance prediction can effectively reduce the construction risk during tunnel excavation.Compared with the 2-D method,the 3-D method is more conducive to describing the spatial characteristics of the ge...Tunnel seismic advance prediction can effectively reduce the construction risk during tunnel excavation.Compared with the 2-D method,the 3-D method is more conducive to describing the spatial characteristics of the geological body by adding the seismic data in the vertical direction.However,some drawbacks still need improvement in the current 3-D tunnel seismic prediction method.(1)The geometry is complex,which is destructiveness,high cost,and time-consuming,and will delay the tunnel construction schedule.(2)Illumination of the anomalous body is insufficient,and the precision of migration imaging is low.(3)Shot points are far away from the tunnel face,the energy loss at the shot points is more serious.(4)The received signals at the tunnel wall have the surface wave with strong energy when the shot points are placed on the tunnel wall.(5)The geometry is not linear,so the directional filtering method cannot be used to extract the reflection wave.To overcome the drawbacks of the current prediction method,a new 3-D symmetrical tunnel seismic prediction method is proposed.Six geophones are installed on the tunnel wall,two on the left side,two on the right side,and two on the top side.Twenty-four shot points are placed on the tunnel face and near both sides of the tunnel wall,twelve shot points on the left side and twelve shot points on the right side.The shot points will move along with the forward excavation of the tunnel.The wavefield analysis,illumination statistics,and 3-D reverse time migration imaging are used to evaluate the proposed method.The result of modeled data indicates that the proposed 3-D geometry has some advantages:(1)the geometry is simple and the geophone installation time is short;(2)it has high illumination energy,wide illumination range,and can improve the prediction distance and imaging accuracy;(3)the proposed 3-D method can better estimate the velocity of surrounding rock and is more conducive to extracting the reflection wave with high resolution.展开更多
There has been growing interest in the high-entropy ceramic(HEC)recently owing to its tailorable compositions and microstructures,versatile properties,together with promising structural and functional applications.How...There has been growing interest in the high-entropy ceramic(HEC)recently owing to its tailorable compositions and microstructures,versatile properties,together with promising structural and functional applications.However,inferior fracture toughness(KIC)and damage tolerance restricted many practical applications of the HEC.Herein,we addressed this challenge by incorporating a threedimensional graphene–carbon nanotube(3D G–CNT)as toughening agent in(Hf_(0.2)Nb_(0.2)Ta_(0.2)Ti_(0.2)Zr_(0.2))C.The resulting enhanced 3D G–CNT/(Hf_(0.2)Nb_(0.2)Ta_(0.2)Ti_(0.2)Zr_(0.2))C featured an outstanding toughness of 8.23 MPa·m^(1/2),while remaining superior strength(763 MPa)and hardness(24.7 GPa).An ultralow friction coefficient(0.15)coupled with an ultralow wear rate(w,2.6×10^(−7) mm^(3)/(N·m))in the 3D G–CNT/(Hf_(0.2)Nb_(0.2)Ta_(0.2)Ti_(0.2)Zr_(0.2))C was obtained primarily as a function of lubricating scrolls,in which two-dimensional(2D)graphene acted as a tribolayer,and one-dimensional(1D)carbon nanotubes acted as nano ball bearings embedded inside.Strikingly,the 3D G–CNT/(Hf_(0.2)Nb_(0.2)Ta_(0.2)Ti_(0.2)Zr_(0.2))C exhibited rather low thermal conductivity(κ)yet excellent electrical conductivity(σ,1.3×10^(6) S/m)in comparison with the pure(Hf_(0.2)Nb_(0.2)Ta_(0.2)Ti_(0.2)Zr_(0.2))C.This study provided great potential for maximizing the physical and functional properties of the HEC for various applications.展开更多
The incidence of refractory mycoplasma pneumoniae pneumonia(RMPP)in children is increasing year by year,and the disease is progressing rapidly.It is accompanied by serious complications and legacy effects,seriously af...The incidence of refractory mycoplasma pneumoniae pneumonia(RMPP)in children is increasing year by year,and the disease is progressing rapidly.It is accompanied by serious complications and legacy effects,seriously affecting the quality of life of children.The selection,dosage,and course of anti-MP drugs in children with RMPP have brought a lot of troubles to pediatric hospitals.In the present study,the characteristics,usage and dosage,drug resistance mechanism,and treatment progress of anti-MP drugs for the treatment of RMPP in children were reviewed.Collectively,our findings provided ideas for the treatment of children with RMPP using anti-MP drugs.展开更多
Rice grain size is an important trait that affects rice yield and quality, and thus the identification of genes related to grain size is of great significance for improving rice yield and quality. Many genes related t...Rice grain size is an important trait that affects rice yield and quality, and thus the identification of genes related to grain size is of great significance for improving rice yield and quality. Many genes related to grain size, such as DEP1(Huang et al., 2009),GW5(Liu et al., 2017).展开更多
Attempts for higher output power and thermal efficiency of gas turbines make the inlet temperature of turbine to be far beyond the material melting temperature.Therefore,to protect the airfoil in gas turbine from hot ...Attempts for higher output power and thermal efficiency of gas turbines make the inlet temperature of turbine to be far beyond the material melting temperature.Therefore,to protect the airfoil in gas turbine from hot gas and eventually prolong the lifetime of the blade,internal and film cooling structures with better thermal performance and cooling effectiveness are urgently needed.However,the traditional way of proceeding involves numerous simulations,additional experiments,and separate trials.Optimization of turbine cooling structures is an effective way to achieve better structures with higher overall performances while considering the multiple objectives,disciplines or subsystems.In this context,this paper reviews optimization research works on film cooling structures and internal cooling structures in gas turbines by means of various optimization methods.This review covers the following aspects:(A)optimization of film cooling conducted on flat plates and on turbine blades or vanes;(B)optimization of jet impingement cooling structures;(C)optimization of rib shapes,dimple shapes,pin–fin arrays in the cooling channels;(D)optimization of U-bend shaped cooling channels,and internal cooling systems of turbine blades or vanes.The review shows that through a reliable and accurate optimization procedure combined with conjugate heat transfer analysis,higher overall thermal performance can be acquired for single-objective or multi-objectives balanced by other constrained conditions.Future ways forward are pointed out in this review.展开更多
To study the mechanism and evolution process of water inrush geohazards under the complex geological environment of the karst cave-fractured zone,a large-scale physical threedimensional(3 D)model test was first perfor...To study the mechanism and evolution process of water inrush geohazards under the complex geological environment of the karst cave-fractured zone,a large-scale physical threedimensional(3 D)model test was first performed.Then the conceptual model for the evolution process of water inrush geohazards and the simplified theoretical model for the critical hydraulic pressure were both established based on the main characteristics of the water inrush geohazard in the engineering background and that in the model test.A new method was developed for modeling the geological environment of the karst cave-structural plane,and two formulae describing the critical water pressure of water inrush geohazards under two failure models of tensile-shear fracture failure and compressionshear fracture failure were also deduced based on fracture mechanics.The results showed that:(1)the evolution process of the water inrush geohazard can be divided into four stages,which include the initial balance,the propagation of original cracks,the formation of the dominant water inrush channel,and the instability of the waterproof rock mass;(2)the suddenness of water inrush geohazards becomes stronger with the increase of the hydraulic pressure;(3)the calculated critical hydraulic pressure of water inrush geohazards is similar to the measured critical hydraulic pressure in the model test,which validated the accuracies of the theoretical model,and the failure model of water inrush geohazards in this research is compression-shear fracture failure.展开更多
Duchenne muscular dystrophy(DMD)is one of the most common and severest muscular dystrophies.Although it can be a cause of death when associated with cardiac muscle and/or respiratory muscles,no cases of sudden deaths ...Duchenne muscular dystrophy(DMD)is one of the most common and severest muscular dystrophies.Although it can be a cause of death when associated with cardiac muscle and/or respiratory muscles,no cases of sudden deaths in the setting of undiagnosed DMD with cardiac involvement have been reported in the literatures.Previous studies showed that N-terminal-proBNP(NT-proBNP)was a robust laboratory biomarker to diagnose and monitor cardiac failure in clinical situations,suggesting that it may be used as an auxiliary indicator for diagnosis on left ventricular dysfunction in sudden cardiac deaths in forensic settings.Here,we reported a case of 29-year-old man who died suddenly.Autopsy revealed that muscles of the body were almost replaced by fatty and fibrotic tissues.The heart was enlarged with disarray and degeneration of cardiomyocytes in cardiac muscle.Total absence of dystrophin was detected by immunohistochemical staining,which confirmed DMD.Postmortem biochemical test of pericardial fluid revealed a high level of NT-proBNP,indicating dysfunction of the left ventricle before death.The cause of death was certified as an early dilated cardiomyopathy(DCM)/dysfunction of the left ventricle secondary to DMD,suggesting that sudden cardiac death with cardiac dysfunction could be identified by immunohistochemical method in combination with pericardial fluid NT-proBNP determination after systemic autopsy.展开更多
A granular material is a conglomeration of discrete solid particles.It is intrinsically athermal because its dynamics always occur far from equilibrium.In highly excited gaseous states,it can safely be assumed that on...A granular material is a conglomeration of discrete solid particles.It is intrinsically athermal because its dynamics always occur far from equilibrium.In highly excited gaseous states,it can safely be assumed that only binary interactions occur and a number of kinetic theories have been successfully applied.However,for granular flows and solidlike states,the theory is still poorly understood because of the internally correlated structures,such as particle clusters and force networks.The current theory is that the mesoscale characteristics define the key differences between granular materials and homogeneous solid materials.Widespread interest in granular materials has arisen among physicists,and significant progress has been made,especially in understanding the jamming phase diagram and the characteristics of the jammed phase.In this paper,the underlying physics of the mesoscale structure is discussed in detail.A multiscale framework is then proposed for dense granular materials.展开更多
基金funded by the National Natural Science Foundation of China(Grant Nos.22279092 and 5202780089).
文摘Li-rich layered oxide(LRLO)cathodes have been regarded as promising candidates for next-generation Li-ion batteries due to their exceptionally high energy density,which combines cationic and anionic redox activities.However,continuous voltage decay during cycling remains the primary obstacle for practical applications,which has yet to be fundamentally addressed.It is widely acknowledged that voltage decay originates from the irreversible migration of transition metal ions,which usually further exacerbates structural evolution and aggravates the irreversible oxygen redox reactions.Recently,constructing O2-type structure has been considered one of the most promising approaches for inhibiting voltage decay.In this review,the relationship between voltage decay and structural evolution is systematically elucidated.Strategies to suppress voltage decay are systematically summarized.Additionally,the design of O2-type structure and the corresponding mechanism of suppressing voltage decay are comprehensively discussed.Unfortunately,the reported O2-type LRLO cathodes still exhibit partially disordered structure with extended cycles.Herein,the factors that may cause the irreversible transition metal migrations in O2-type LRLO materials are also explored,while the perspectives and challenges for designing high-performance O2-type LRLO cathodes without voltage decay are proposed.
基金supported by the National Natural Science Foundations of China under Grant Nos.52206123,52075506,52205543,52322510,52275470 and 52105129Science and Technology Planning Project of Sichuan Province under Grant No.2021YJ0557+2 种基金Natural Science Foundation of Sichuan Province under Grant No.2023NSFSC1947Presidential Foundation of China Academy of Engineering PhysicsGrant No.YZJJZQ2022009。
文摘Fluid lubricated bearings have been widely adopted as support components for high-end equipment in metrology,semiconductor devices,aviation,strategic defense,ultraprecision manufacturing,medical treatment,and power generation.In all these applications,the equipment must deliver extreme working performances such as ultraprecise movement,ultrahigh rotation speed,ultraheavy bearing loads,ultrahigh environmental temperatures,strong radiation resistance,and high vacuum operation,which have challenged the design and optimization of reliable fluid lubricated bearings.Breakthrough of any related bottlenecks will promote the development course of high-end equipment.To promote the advancement of high-end equipment,this paper reviews the design and optimization of fluid lubricated bearings operated at typical extreme working performances,targeting the realization of extreme working performances,current challenges and solutions,underlying deficiencies,and promising developmental directions.This paper can guide the selection of suitable fluid lubricated bearings and optimize their structures to meet their required working performances.
基金financially supported by the National Key R&D Program of China(No.2018YFC1900500)the National Natural Science Foundation of China(Nos.21908231,51774260,51804289,and 51904286)+2 种基金the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences(No.QYZDJ-SSW-JSC021)the CAS Interdisciplinary Innovation Teamthe Special Project for Transformation of Major Technological Achievements in Hebei Province,China(No.19044012Z)。
文摘The carbothermic reduction of vanadium titanomagnetite concentrate(VTC)with the assistance of Na_(2)CO_(3)was conducted in an argon atmosphere between 1073 and 1473 K.X-ray diffraction and scanning electron microscopy were used to investigate the phase transformations during the reaction.By investigating the reaction between VTC and Na_(2)CO_(3),it was concluded that molten Na_(2)CO_(3)broke the structure of titanomagnetite by combining with the acidic oxides(Fe_(2)O_(3),TiO_(2),Al_(2)O_(3),and SiO_(2))to form a Na-rich melt and release FeO and MgO.Therefore,Na_(2)CO_(3)accelerated the reduction rate.In addition,adding Na_(2)CO_(3)also benefited the agglomeration of iron particles and the slag–metal separation by decreasing the viscosity of the slag.Thus,Na_(2)CO_(3)assisted carbothermic reduction is a promising method for treating VTC at low temperatures.
基金the Natural Science Foundation of Guangdong Province,No.04009355Science and Technology Planning Project of Guandong Province,China,05B33801003
文摘BACKGROUND： Rifampicin inhibits the formation of a-synuclein multimer and protects against 1-methyl-4-phenyl-1,2, 3, 6-tetrahydropyritine （MPTP）-induced PC12 cell apoptosis. OBJECTIVE： To compare the effect of rifampicin pre- and post-treatment on tyrosine hydroxylase and α-synuclein expression in substantia nigra pars compacta in a rat model of Parkinson＇s disease. DESIGN, TIME AND SE＇B＇ING： A randomized, controlled experiment was performed at the Experimental Animal Center of Sun Yat-sen University North Campus （China） from November 2006 to October 2008. MATERIALS： Rifampicin was purchased from MD, USA; rotenone was purchased from Sigma, USA; mouse anti-rat α-synuclein monoclonal antibody was purchased from B＆D, USA; and rabbit anti-rat tyrosine hydroxylase monoclonal antibody was purchased from Chemicon, USA. METHODS： A total of 72 male, Sprague Dawley rats, aged 8 weeks, were randomly assigned to 5 groups： blank control （n = 12）, rifampicin （n = 12）, rotenone （n = 16）, rifampicin pre-treatment （n = 16）, and rifampicin post-treatment （n = 16）. Parkinson＇s disease model rats were established via a subcutaneous injection of rotenone （1.5 mg/kg per day） in the three treatment groups, once a day for 3 successive weeks. Rifampicin （30 mg/kg per day） was intragastrically administered in the rifampicin pre-treatment group 3 days prior to rotenone induction and in the rifampicin post-treatment group 7 days after rotenone induction. Rats were treated with a subcutaneous injection of 1 mL/kg per day sunflower oil in the blank control group and an intragastric injection of 30 mg/kg per day rifampicin in the rifampicin group, once a day for 3 successive weeks in total. MAIN OUTCOME MEASURES： Prior to treatment and in the end of the 3^rd week after treatment, the rats were evaluated using the modified neurological severity score. The substantia nigra from the rats was extracted for hematoxylin-eosin staining. Western blot analysis was performed to determine tyrosine hydroxylase and α-synuclein expression. RESULTS： Hematoxylin-eosin staining revealed a significant reduction in the number of substantia nigral neurons in the rotenone group, in addition to neurodegradation, hypopigmentation, and pyknosis. In the rifampicin pre-treatment and post-treatment groups, the number of dopaminergic neurons was significantly increased compared with the rotenone group （P 〈 0.01）, with slight neuronal damage. Compared with the rotenone group, substantia nigral tyrosine hydroxylase expression was significantly increased in the rifampicin pre-treatment and post-treatment groups （P 〈 0.01）, but α-synuclein expression and modified neurological severity scores were significantly decreased （P 〈 0.01）. In addition, the effect of rifampicin in the pre-treatment group was superior to the post-treatment group. There was no significant difference in tyrosine hydroxylase and α-synuclein expression, or in the modified neurological severity scores, between the blank control and rifampicin groups （P 〉 0.05）. CONCLUSION： Rifampicin significantly attenuated neuropathological and behavioral motor deficits induced by rotenone. Moreover, rifampicin enhanced tyrosine hydroxylase expression, but inhibited α-synuclein expression. The effect of rifampicin pre-treatment was superior to rifampicin post-treatment.
基金The project supported by the National Natural Science Foundation of China(50309003)
文摘By using the momentum theorem and waterbalance principle, basic equations of slope runoff were derived, soil erosion by raindrop splash and runoff were discussed and a model was established for decribing hillslope soil erosion processes. The numerical solution of the model was obtained by adopting the Preissmann format and considering the common solution-determining conditions, from which not only the runoff and soil erosion but also their processes can be described. The model was validated by ten groups of observation data of Soil Conservation Ecological Science and Technology Demonstration Park of Jiangxi Province. Comparisons show that the maximum relative error between simulation and experimental data is about 10.98% for total runoff and 15 % for total erosion, 5.2% for runoffprocess and 6.1% for erosion process, indicating that the model is conceptually realistic and reliable and offers a feasible approach for further studies on the soil erosion process.
基金the Fundamental Research Funds for the Central Universities,China(No.FRF-IDRY-19-012).
文摘ZrC and ZrB2 are both typical ultra-high temperature ceramics,which can be used in the hyperthermal environment.In this study,a method for preparing ultrafine ZrC-ZrB2 composite powder was provided,by using the raw materials of nano ZrO2,carbon black,B4C,and metallic Ca.It is worth pointing out that ZrC-ZrB2 composite powder with any proportion of ZrC to ZrB2 could be synthesized by this method.Firstly,a mixture of ZrC and C was prepared by carbothermal reduction of ZrO2.By adjusting the addition amount of B4C,ZrC was boronized by B4C to generate ZrC-ZrB2 composite powder with different compositions.Using this method,five composite powders with different molar ratios of ZrC and ZrB2(100ZrC,75ZrC-25ZrB2,50ZrC-50ZrB2,25ZrC-75ZrB2,and 100ZrB2)were prepared.When the temperature of boronization and decarburization process was 1473 K,the particle size of product was only tens of nanometres.Finally,the oxidation charac-teristics of different composite powders were investigated through oxidation experiments.The oxidation resistance of ZrC-ZrB2 composite powder continued to increase as the content of ZrB2 increased.
文摘Our research was designed to explore the more effective rescuing treatment by summarizing clinical features of the patients with myasthenia gravis crisis. During the course, we carried out a retrospective analysis about clinical data and the course of diagnose and treatment of 38 patients (65 cases) with myasthenia gravis crisis who were in hospital in recent 15 years. As a result, most patients with myasthenia gravis crisis relieved after positive treatment and the mortality was 3.1%. Among lots of treatments, incision of trachea earlier, hormonal therapy, dry treatment and to unite these three treatments were more effective than other treatments. The effective ratio was 100%. In the end, we concluded that to unite incision of trachea, immunosuppressive treatment and dry treatment reasonably can increase the effective ratio of rescuing myasthenia gravis crisis and improve the prognosis of patients obviously.
基金supported by the National Natural Science Foundation of China(42130611)Guangdong Foundation for Program of Science and Technology Research(2023B1212060049,2019B121205006).
文摘The environmental stability of infectious viruses in the laboratory setting is crucial to the transmission potential of human respiratory viruses.Different experimental techniques or conditions used in studies over the past decades have led to diverse understandings and predictions for the stability of viral infectivity in the atmospheric environment.In this paper,we review the current knowledge on the effect of simulated atmospheric conditions on the infectivity of respiratory viruses,mainly focusing on influenza viruses and coronaviruses,including severe acute respiratory syndrome coronavirus 2 and Middle East respiratory syndrome coronavirus.First,we summarize the impact of the experimental conditions on viral stability;these involve the methods of viral aerosol generation,storage during aging and collection,the virus types and strains,the suspension matrixes,the initial inoculum volumes and concentrations,and the drying process.Second,we summarize and discuss the detection methods of viral infectivity and their disadvantages.Finally,we integrate the results from the reviewed studies to obtain an overall understanding of the effects of atmospheric environmental conditions on the decay of infectious viruses,especially aerosolized viruses.Overall,this review highlights the knowledge gaps in predicting the ability of viruses to maintain infectivity during airborne transmission.
基金funded by the National Natural Science Foundation of China(No.41731284)。
文摘Tunnel seismic advance prediction can effectively reduce the construction risk during tunnel excavation.Compared with the 2-D method,the 3-D method is more conducive to describing the spatial characteristics of the geological body by adding the seismic data in the vertical direction.However,some drawbacks still need improvement in the current 3-D tunnel seismic prediction method.(1)The geometry is complex,which is destructiveness,high cost,and time-consuming,and will delay the tunnel construction schedule.(2)Illumination of the anomalous body is insufficient,and the precision of migration imaging is low.(3)Shot points are far away from the tunnel face,the energy loss at the shot points is more serious.(4)The received signals at the tunnel wall have the surface wave with strong energy when the shot points are placed on the tunnel wall.(5)The geometry is not linear,so the directional filtering method cannot be used to extract the reflection wave.To overcome the drawbacks of the current prediction method,a new 3-D symmetrical tunnel seismic prediction method is proposed.Six geophones are installed on the tunnel wall,two on the left side,two on the right side,and two on the top side.Twenty-four shot points are placed on the tunnel face and near both sides of the tunnel wall,twelve shot points on the left side and twelve shot points on the right side.The shot points will move along with the forward excavation of the tunnel.The wavefield analysis,illumination statistics,and 3-D reverse time migration imaging are used to evaluate the proposed method.The result of modeled data indicates that the proposed 3-D geometry has some advantages:(1)the geometry is simple and the geophone installation time is short;(2)it has high illumination energy,wide illumination range,and can improve the prediction distance and imaging accuracy;(3)the proposed 3-D method can better estimate the velocity of surrounding rock and is more conducive to extracting the reflection wave with high resolution.
基金supported by the National Natural Science Foundation of China (No.52005396)Young Talent Fund of University Association for Science and Technology in Shaanxi (No.20210414)Qilu Youth Scholar Project Funding of Shandong University (No.1050522300003).
文摘There has been growing interest in the high-entropy ceramic(HEC)recently owing to its tailorable compositions and microstructures,versatile properties,together with promising structural and functional applications.However,inferior fracture toughness(KIC)and damage tolerance restricted many practical applications of the HEC.Herein,we addressed this challenge by incorporating a threedimensional graphene–carbon nanotube(3D G–CNT)as toughening agent in(Hf_(0.2)Nb_(0.2)Ta_(0.2)Ti_(0.2)Zr_(0.2))C.The resulting enhanced 3D G–CNT/(Hf_(0.2)Nb_(0.2)Ta_(0.2)Ti_(0.2)Zr_(0.2))C featured an outstanding toughness of 8.23 MPa·m^(1/2),while remaining superior strength(763 MPa)and hardness(24.7 GPa).An ultralow friction coefficient(0.15)coupled with an ultralow wear rate(w,2.6×10^(−7) mm^(3)/(N·m))in the 3D G–CNT/(Hf_(0.2)Nb_(0.2)Ta_(0.2)Ti_(0.2)Zr_(0.2))C was obtained primarily as a function of lubricating scrolls,in which two-dimensional(2D)graphene acted as a tribolayer,and one-dimensional(1D)carbon nanotubes acted as nano ball bearings embedded inside.Strikingly,the 3D G–CNT/(Hf_(0.2)Nb_(0.2)Ta_(0.2)Ti_(0.2)Zr_(0.2))C exhibited rather low thermal conductivity(κ)yet excellent electrical conductivity(σ,1.3×10^(6) S/m)in comparison with the pure(Hf_(0.2)Nb_(0.2)Ta_(0.2)Ti_(0.2)Zr_(0.2))C.This study provided great potential for maximizing the physical and functional properties of the HEC for various applications.
基金Science and Technology Plan Project of Jinan Health Committee(Grant No.2021-1-08)。
文摘The incidence of refractory mycoplasma pneumoniae pneumonia(RMPP)in children is increasing year by year,and the disease is progressing rapidly.It is accompanied by serious complications and legacy effects,seriously affecting the quality of life of children.The selection,dosage,and course of anti-MP drugs in children with RMPP have brought a lot of troubles to pediatric hospitals.In the present study,the characteristics,usage and dosage,drug resistance mechanism,and treatment progress of anti-MP drugs for the treatment of RMPP in children were reviewed.Collectively,our findings provided ideas for the treatment of children with RMPP using anti-MP drugs.
基金supported by the grants from the National Key Research and Development Program of China (2016YFD0100406)the Rice Molecular Design Breeding (2016YFD0101801)+1 种基金the National Natural Science Foundation of China (91535102 and 31771760)the Open Research Fund of State Key Laboratory of Hybrid Rice (Hunan Hybrid Rice Research Center) (2016KF09)
文摘Rice grain size is an important trait that affects rice yield and quality, and thus the identification of genes related to grain size is of great significance for improving rice yield and quality. Many genes related to grain size, such as DEP1(Huang et al., 2009),GW5(Liu et al., 2017).
基金supported by the National Natural Science Foundation of China (No. 51676163)the National 111 Project, China (No. B18041the Guangdong Basic and Applied Basic Research Foundation, China (No. 2019A1515111146)
文摘Attempts for higher output power and thermal efficiency of gas turbines make the inlet temperature of turbine to be far beyond the material melting temperature.Therefore,to protect the airfoil in gas turbine from hot gas and eventually prolong the lifetime of the blade,internal and film cooling structures with better thermal performance and cooling effectiveness are urgently needed.However,the traditional way of proceeding involves numerous simulations,additional experiments,and separate trials.Optimization of turbine cooling structures is an effective way to achieve better structures with higher overall performances while considering the multiple objectives,disciplines or subsystems.In this context,this paper reviews optimization research works on film cooling structures and internal cooling structures in gas turbines by means of various optimization methods.This review covers the following aspects:(A)optimization of film cooling conducted on flat plates and on turbine blades or vanes;(B)optimization of jet impingement cooling structures;(C)optimization of rib shapes,dimple shapes,pin–fin arrays in the cooling channels;(D)optimization of U-bend shaped cooling channels,and internal cooling systems of turbine blades or vanes.The review shows that through a reliable and accurate optimization procedure combined with conjugate heat transfer analysis,higher overall thermal performance can be acquired for single-objective or multi-objectives balanced by other constrained conditions.Future ways forward are pointed out in this review.
基金supported by the National Natural Science Foundation of China(Nos.41731284,41920104007)。
文摘To study the mechanism and evolution process of water inrush geohazards under the complex geological environment of the karst cave-fractured zone,a large-scale physical threedimensional(3 D)model test was first performed.Then the conceptual model for the evolution process of water inrush geohazards and the simplified theoretical model for the critical hydraulic pressure were both established based on the main characteristics of the water inrush geohazard in the engineering background and that in the model test.A new method was developed for modeling the geological environment of the karst cave-structural plane,and two formulae describing the critical water pressure of water inrush geohazards under two failure models of tensile-shear fracture failure and compressionshear fracture failure were also deduced based on fracture mechanics.The results showed that:(1)the evolution process of the water inrush geohazard can be divided into four stages,which include the initial balance,the propagation of original cracks,the formation of the dominant water inrush channel,and the instability of the waterproof rock mass;(2)the suddenness of water inrush geohazards becomes stronger with the increase of the hydraulic pressure;(3)the calculated critical hydraulic pressure of water inrush geohazards is similar to the measured critical hydraulic pressure in the model test,which validated the accuracies of the theoretical model,and the failure model of water inrush geohazards in this research is compression-shear fracture failure.
文摘Duchenne muscular dystrophy(DMD)is one of the most common and severest muscular dystrophies.Although it can be a cause of death when associated with cardiac muscle and/or respiratory muscles,no cases of sudden deaths in the setting of undiagnosed DMD with cardiac involvement have been reported in the literatures.Previous studies showed that N-terminal-proBNP(NT-proBNP)was a robust laboratory biomarker to diagnose and monitor cardiac failure in clinical situations,suggesting that it may be used as an auxiliary indicator for diagnosis on left ventricular dysfunction in sudden cardiac deaths in forensic settings.Here,we reported a case of 29-year-old man who died suddenly.Autopsy revealed that muscles of the body were almost replaced by fatty and fibrotic tissues.The heart was enlarged with disarray and degeneration of cardiomyocytes in cardiac muscle.Total absence of dystrophin was detected by immunohistochemical staining,which confirmed DMD.Postmortem biochemical test of pericardial fluid revealed a high level of NT-proBNP,indicating dysfunction of the left ventricle before death.The cause of death was certified as an early dilated cardiomyopathy(DCM)/dysfunction of the left ventricle secondary to DMD,suggesting that sudden cardiac death with cardiac dysfunction could be identified by immunohistochemical method in combination with pericardial fluid NT-proBNP determination after systemic autopsy.
基金The authors acknowledge the support of the National Basic Research Program of China(Grant No.2010CB731504)the National Natural Science Foundation of China(Grant No.51239006,11272048).
文摘A granular material is a conglomeration of discrete solid particles.It is intrinsically athermal because its dynamics always occur far from equilibrium.In highly excited gaseous states,it can safely be assumed that only binary interactions occur and a number of kinetic theories have been successfully applied.However,for granular flows and solidlike states,the theory is still poorly understood because of the internally correlated structures,such as particle clusters and force networks.The current theory is that the mesoscale characteristics define the key differences between granular materials and homogeneous solid materials.Widespread interest in granular materials has arisen among physicists,and significant progress has been made,especially in understanding the jamming phase diagram and the characteristics of the jammed phase.In this paper,the underlying physics of the mesoscale structure is discussed in detail.A multiscale framework is then proposed for dense granular materials.
