Due to their environmentally friendly nature and high energy density,direct ethanol fuel cells have attracted extensive research attention in recent decades.However,the actual Faraday efficiency of the ethanol oxidati...Due to their environmentally friendly nature and high energy density,direct ethanol fuel cells have attracted extensive research attention in recent decades.However,the actual Faraday efficiency of the ethanol oxidation reaction(EOR)is much lower than its theoretical value and the reaction kinetics of the EOR is sluggish due to insufficient active sites on the electrocatalyst surface.Pt/C is recognized as one of the most promising electrocatalysts for the EOR.Thus,the microscopic interfacial reaction mechanisms of the EOR on Pt/C were systematically studied in this work.In metal hydroxide solutions,hydrated alkali cations were found to bind with OH_(ad)through noncovalent interactions to form clusters and occupy the active sites on the Pt/C electrocatalyst surface,thus resulting in low Faraday efficiency and sluggish kinetics of the EOR.To reduce the negative effect of the noncovalent interactions on the EOR,a shield was made on the electrocatalyst surface using 4-trifluoromethylphenyl,resulting in twice the EOR catalytic reactivity of Pt/C.展开更多
Since the application in fuel cell,the electrochemical adsorption of hydroxyl has received considerable attention in recent years.While most research mainly focus on the room temperature,in this paper,the electrochemi...Since the application in fuel cell,the electrochemical adsorption of hydroxyl has received considerable attention in recent years.While most research mainly focus on the room temperature,in this paper,the electrochemical adsorption of hydroxyl in alkaline solution at high temperature was investigated.An unusual oxidation peak was observed at-0.27 V,suggesting new behavior of hydroxyl adsorption occurred.As is known two kinds of cation hydrated clusters exist in alkaline solution,(H_(2)O)_(x-1)M^(+)-H_(2)O-O_(ad)H and(H_(2)O)_xM^(+)-O_(ad)H.For K^(+)and Cs^(+),the cluster shows unstable structure due to the weak interaction between hydrated cation and OH^(-)especially at high temperature.However,For Li^(+),Na^(+)the cluster structure would be stable,as the interaction force between the hydrated cation and OH^(-)is so strong.It was revealed that the unusual oxidation peak has some relationship with the(H_(2)O)_(x-1)M^(+)-H_(2)O-O_(ad)H cluster(K^(+)and Cs^(+))absorbed at Pt electrode surface.When the temperature was raised,(H_(2)O)_(x-1)M^(+)-H_(2)O-and-O_(ad)H was disconnected,then the O_(ad)H absorbed at Pt surface got oxidated.Based on the SEM observation,it was showed the unusual electrochemical oxidation reaction would generate platinum oxides,blocking the reactive sites at Pt electrode surface,thus reducing the electrochemical reactivity of Pt electrode.Accordingly,parameters of alkaline concentration and temperature were systematically studied,it was found that increase temperature or alkaline concentration was in favor of the unusual oxidation reaction.This study provides more understanding of hydroxyl adsorption behavior at Pt electrode surface for the high temperature water solution environment.展开更多
To recycle vanadium and chromium from the V?Cr-bearing reducing slag,the thermodynamics of separating V(IV)and Cr(III)at 298 K was summarized in the form of potential-pH diagram and activity-pH diagram.The potential-p...To recycle vanadium and chromium from the V?Cr-bearing reducing slag,the thermodynamics of separating V(IV)and Cr(III)at 298 K was summarized in the form of potential-pH diagram and activity-pH diagram.The potential-pH diagrams of V-Mn-H2O and Cr-Mn-H2O systems show that the electrode potential of MnO2/Mn2+is higher than that of VO2+/VO2+but lower than that of Cr2O7 2-/Cr3+,which proves that it is feasible to selectively oxidize low valent vanadium using MnO2.The activity-pH diagrams of V(V)-H2O and Cr(III)-H2O systems show that the precipitation pH of V(V)is far lower than that of Cr(III),and therefore V(V)and Cr(III)can be separated through precipitation method.Based on the thermodynamic analysis,the flowsheet of recovery of vanadium and chromium from the V-Cr-bearing reducing slag is designed.展开更多
The separation and recovery of Ni from the copper electrolyte by crystallization of nickel ammonium sulfate double salt were studied.It is found that the solubility of copper sulfate at the same temperature is less th...The separation and recovery of Ni from the copper electrolyte by crystallization of nickel ammonium sulfate double salt were studied.It is found that the solubility of copper sulfate at the same temperature is less than that of nickel sulfate,while the solubility of copper ammonium sulfate is greater than that of nickel ammonium sulfate.So,by adding(NH_(4))_(2)SO_(4),the Ni can be selectively crystallized from the copper electrolyte.By adding(NH_(4))_(2)SO_(4)at the molar ratio of(NH_(4))_(2)SO_(4)/NiSO_(4)≤0.8,and crystallizing at−15℃for 10 h,the Ni in the copper electrolyte can be crystallized in the form of Ni(NH_(4))_(2)(SO_(4))_(2)×6H_(2)O.The qualified product of NiSO_(4)×6H_(2)O can be obtained by pyrolyzing the crystals,dissolving the pyrolysis product in water,and then concentrating the dissolved solution for crystallization.The method of double salt crystallization is a clean,environmentally-friendly,cost-effective and efficient method for separating and recovering nickel from copper electrolyte.展开更多
In this study, we aimed to explore the role of ursolic acid in the neural regeneration of the injured sciatic nerve. BALB/c mice were used to establish models of sciatic nerve injury through unilateral sciatic nerve c...In this study, we aimed to explore the role of ursolic acid in the neural regeneration of the injured sciatic nerve. BALB/c mice were used to establish models of sciatic nerve injury through unilateral sciatic nerve complete transection and microscopic anastomosis at 0.5 cm below the ischial tuber-osity. The successful y generated model mice were treated with 10, 5, or 2.5 mg/kg ursolic acid via intraperitoneal injection. Enzyme-linked immunosorbent assay results showed that serum S100 protein expression level gradual y increased at 1-4 weeks after sciatic nerve injury, and significantly decreased at 8 weeks. As such, ursolic acid has the capacity to significantly increase S100 protein expression levels. Real-time quantitative PCR showed that S100 mRNA expression in the L 4-6 segments on the injury side was increased after ursolic acid treatment. In addition, the muscular mass index in the soleus muscle was also increased in mice treated with ursolic acid. Toluidine blue staining revealed that the quantity and average diameter of myelinated nerve fibers in the injured sciatic nerve were significantly increased after treatment with ursolic acid. 10 and 5 mg/kg of ursolic acid produced stronger effects than 2.5 mg/kg of ursolic acid. Our findings indicate that ursolic acid can dose-dependently increase S100 expression and promote neural regeneration in BALB/c mice fol owing sciatic nerve injury.展开更多
Biological bipolar metaplasticities were successfully mimicked in two-dimensional(2D)MoS2 transistors via the implementation of two different MoS2 surface decorations,poly(vinyl alcohol)(PVA)and chitosan bio-polymers....Biological bipolar metaplasticities were successfully mimicked in two-dimensional(2D)MoS2 transistors via the implementation of two different MoS2 surface decorations,poly(vinyl alcohol)(PVA)and chitosan bio-polymers.Interestingly,the depressing metaplasticity was successfully mimicked when the PVA bio-polymer was used as the surface decoration layer,whereas the metaplasticity of long-term potentiation was realized when the chitosan bio-polymer was taken as the surface decoration layer.Furthermore,the electronic band structures of the 2D MoS2 devices with different surface decorations were further investigated using first-principles calculations for understanding the underlying mechanisms of such bipolar metaplasticities.These results will deepen our understanding of metaplasticity,and have great potential in neuromorphic computing applications.展开更多
Directional modulation is one of the hot topics in data security researches.To fulfill the requirements of communication security in wireless environment with multiple paths,this study takes into account the factors o...Directional modulation is one of the hot topics in data security researches.To fulfill the requirements of communication security in wireless environment with multiple paths,this study takes into account the factors of reflections and antenna radiation pattern for directional modulation.Unlike other previous works,a novel multiple-reflection model,which is more realistic and complex than simplified two-ray reflection models,is proposed based on two reflectors.Another focus is a quantum genetic algorithm applied to optimize antenna excitation in a phased directional modulation antenna array.The quantum approach has strengths in convergence speed and the globe searching ability for the complicated model with the large-size antenna array and multiple paths.From this,a phased directional modulation transmission system can be optimized as regards communication safety and improve performance based on the constraint of the pattern of the antenna array.Our work can spur applications of the quantum evolutionary algorithm in directional modulation technology,which is also studied.展开更多
The thin film properties of organic semiconductors are very important to the device performance.Herein,non-planar vanadyl phthalocyanine(VOPc)thin films grown on rigid substrates of indium tin oxide,silicon dioxide,an...The thin film properties of organic semiconductors are very important to the device performance.Herein,non-planar vanadyl phthalocyanine(VOPc)thin films grown on rigid substrates of indium tin oxide,silicon dioxide,and flexible substrate of kapton by organic molecular beam deposition under vacuum conditions are systematically studied via atomic force microscopy and x-ray diffraction.The results clearly reveal that the morphology and grain size are strongly dependent on the substrate temperature during the process of film deposition.Meanwhile,the VOPc films with the structure of phase I or phase II can be modulated via in situ annealing and post-annealing temperature.Furthermore,the crystalline structure and molecular orientation of vapor-deposited VOPc can be controlled using molecular template layer 3,4,9,10-perylenetetracarboxylic dianhydride(PTCDA),the VOPc film of which exhibits the phase I structure.The deep understanding of growth mechanism of non-planar VOPc film provides valuable information for controlling structure-property relationship and accelerates the application in electronic and optoelectronic devices.展开更多
The morphology and interface of perovskite film are very important for the performance of perovskite solar cells(PSCs).The quality of perovskite film,fabricated via two-step spin-coating process,is significantly influ...The morphology and interface of perovskite film are very important for the performance of perovskite solar cells(PSCs).The quality of perovskite film,fabricated via two-step spin-coating process,is significantly influenced by the morphology and crystallinity of PbI2 film.With the addition of additive dimethyl sulfoxide(DMSO)into the PbI2 precursor,the roughness and trap-state density of perovskite film have been significantly reduced,leading to the excellent contact between perovskite layer and subsequent deposited carrier transport layer.Accordingly,the planar heterojunction PSCs with an architecture of ITO/SnO2/perovskite/PTAA/Ag show an efficiency up to 19.02%.Furthermore,PSCs exhibit promising stability in air with a humidity of ~45%,and retain 80% of initial efficiency after being exposed to air for 400 h without any encapsulation.展开更多
Objective:To investigate the epidemic characteristics of multidrug resistant tuberculosis in Hainan,China,to provide basic information and theories for the prevention and control of multidrug resistant tuberculosis.Me...Objective:To investigate the epidemic characteristics of multidrug resistant tuberculosis in Hainan,China,to provide basic information and theories for the prevention and control of multidrug resistant tuberculosis.Methods:A retrospective descriptive epidemiological study was conducted.Data of multidrug resistant tuberculosis in Hainan Island from January 1,2014 to December 31,2019 were collected for statistical analysis.The counting data were described by frequency(percentage),and the measurement data were described by mean±standard deviation.Chi square test was used to compare the differences between different groups.If P<0.05,the difference was statistically significant.Results:From 2014 to 2019,the multidrug resistant rate of tuberculosis in Hainan Island was 24.9%(369/1484),8.0%(63/791)in newly-treated tuberculosis,and 44.2%(306/693)in retreatedmultidrug resistant rate of tuberculosis in Hainan Island was 24.9%(369/1484),8.0%(63/791)in newly-treatedtuberculosis,and 44.2%(306/693)in retreated tuberculosis.The multidrug resistant rate of newly-treated tuberculosis decreased by 0.05%per year,while that of retreated tuberculosis increased by 0.03%per year.multidrug resistant tuberculosis was mainly distributed in the city of Haikou(83 cases),Danzhou(44 cases),Wenchang(42 cases),Wanning(37 cases)and Dongfang(32 cases),accounting for 64.5%of all multidrug resistant tuberculosis.Among 369 multidrug resistant tuberculosis,81.0%were male.The proportion of newly-treated cases was 17.1%(63/369),while the proportion of retreated cases was 82.9%(306/369),which was significantly higher than that of newly-treated cases.The multidrug resistant rate of tuberculosis in different years was different.Conclusion:The drug resistance rate of tuberculosis in Hainan Island is higher than the national average level,which needs attention.The epidemiological characteristics of multidrug resistant tuberculosis with different treatment history were different.展开更多
Mosquitoes are an important medical insect and play a very important role in the process of biologically vector infectious diseases.A large number of bacterial communities are colonized in their intestines.In the proc...Mosquitoes are an important medical insect and play a very important role in the process of biologically vector infectious diseases.A large number of bacterial communities are colonized in their intestines.In the process of interaction and symbiosis with mosquitoes,the bacterial community is in many ways.The life activities of mosquitoes have a significant impact.This article reviews the population structure of the mosquito intestinal flora,influencing factors,and the regulation of mosquito vector efficacy by the flora.展开更多
Based on case study of the practice of smart city development around the world,which has achieved a lot to make our life more convenient,through analysis of advantages and disadvantages,conclusion of some principles c...Based on case study of the practice of smart city development around the world,which has achieved a lot to make our life more convenient,through analysis of advantages and disadvantages,conclusion of some principles could be reached in a qualitative way.After studying the policy and economy environment of China,this paper concludes some features,identifies opportunities and challenges for smart city under the background of“The Belt and Road Initiative”,and provides suggestions on the development of China.展开更多
To develop a simple and fast method for screening genetically modified ingredients from processing by-product and waste,direct quantitative PCR(qPCR)kit-Taqman which omitting multi genomic DNA preparing steps was deve...To develop a simple and fast method for screening genetically modified ingredients from processing by-product and waste,direct quantitative PCR(qPCR)kit-Taqman which omitting multi genomic DNA preparing steps was developed in this study.A total of 18 oil crop processing by-products and wastes including 10 soybean and 8 cotton materials were collected from food processing factories.Compared with 2 commercial direct qPCR kits,conditions of DNA releasing procedure and PCR amplification were optimized.Element screening was performed at the initial step of genetically modified(GM)ingredient testing procedure via direct qPCR.GM event identification was carried out in positive samples by initial screening.Totally 5 screening elements(P–35S,T-NOS,Cp4-epsps,bar and pat)for soybean materials and 6 screening elements(P–35S,T-NOS,NPTII,Cry1Ac,bar and pat)for cotton samples were detected.In GM event identification,MON531 and MON1445 were found in cotton materials.Results were further confirmed by real-time PCR with DNA extraction and purification.The direct qPCR system proposed by this research was convenient for rapid screening and identification of GM ingredients in oil crop primary by-product and waste.展开更多
Cultivating students＇ autonomous learning ability is the inevitable trend of modern education in the information age and lifelong learning. This paper briefly introduces the concept of Autonomous English learning, an...Cultivating students＇ autonomous learning ability is the inevitable trend of modern education in the information age and lifelong learning. This paper briefly introduces the concept of Autonomous English learning, and puts forward how to cultivate students＇ autonomous learning ability. Students activety participate in the learning process and experience/earning process can greatly promote the learning effect. The cultivation of autonomous learning ability is an important guarantee for success in learning English. Therefore, how to improve the autonomous learning ability of English majors is a topic worth exploring. The experimental results show that these strategies can improve students＇ autonomous learning awareness, students ＇ learning initiative and independence, and the ability of autonomous learning is gradually improving展开更多
Side-channel attacks based on supervised learning require that the attacker have complete control over the cryptographic device and obtain a large number of labeled power traces.However,in real life,this requirement i...Side-channel attacks based on supervised learning require that the attacker have complete control over the cryptographic device and obtain a large number of labeled power traces.However,in real life,this requirement is usually not met.In this paper,an attack algorithm based on collaborative learning is proposed.The algorithm only needs to use a small number of labeled power traces to cooperate with the unlabeled power trace to realize the attack to cryptographic device.By experimenting with the DPA contest V4 dataset,the results show that the algorithm can improve the accuracy by about 20%compared with the pure supervised learning in the case of using only 10 labeled power traces.展开更多
Ex vivo tissue culture of the human corpus cavernosum(cc)can be used to explore the tissue structural changes and complex signaling networks.At present,artificial Cc-like tissues based on acellular or three-dimensiona...Ex vivo tissue culture of the human corpus cavernosum(cc)can be used to explore the tissue structural changes and complex signaling networks.At present,artificial Cc-like tissues based on acellular or three-dimensional(3D)-printed scaffolds are used to solve the scarcity of primary penis tissue samples.However,inconvenience and high costs limit the wide application of such methods.Here,we describe a simple,fast,and economical method of constructing artificial CC-like tissue.Human Cc fibroblasts(FBs),endothelial cells(ECs),and smooth muscle cells(SMCs)were expanded in vitro and mixed with Matrigel in specific proportions.A large number of bubbles were formed in the mixture by vortexing combined with pipette blowing,creating a porous,spongy,and spatial structure.The Cc FBs produced a variety of signaling factors,showed multidirectional differentiation potential,and grew in a 3D grid in Matrigel,which is necessary for CC-like tissue to maintain a porous structure as a cell scaffold.Within the C-like tissue,ECs covered the surface of the lumen,and SMCs were located inside the trabeculae,similar to the structure of the primary Cc.Various cell components remained stable for 3 days in vitro,but the EC content decreased on the 7th day.Wingless/integrated(WNT)signaling activation led to lumen atrophy and increased tissue fibrosis in CC-like tissue,inducing the same changes in characteristics as in the primary Cc.This study describes a preparation method for human artificial cC-like tissue that may provide an improved experimental platform for exploring the function and structure of the cC and conducting drug screening for erectile dysfunction therapy.展开更多
Although numerous metal halide perovskite materials have been investigated in the field of optoelectronic,the development of perovskite heterojunctions with exotic structures is still rare.Herein,we report the epitaxi...Although numerous metal halide perovskite materials have been investigated in the field of optoelectronic,the development of perovskite heterojunctions with exotic structures is still rare.Herein,we report the epitaxial growth of quasi-two-dimensional(Q-2D)perovskites on methylammonium lead iodide(MAPbI_(3))single crystals to form perovskite heterojunctions with interfacial bonding.The MAPbI_(3)adjacent to epitaxial Q-2D perovskite shows blue shifted photoluminescence with shortened lifetime,which becomes significant with the reduced layer number of the Q-2D perovskites.Our findings suggest the presence of an interfacial strain gradient leading to enhanced photocarrier separation.Accordingly,compared to the MAPbI_(3)single crystal detector,the BA_(2)MAPb_(2)I_(7)/MAPbI_(3)(BA:n-butylamine)heterojunction-based photodetector demonstrates a bandpass detecting property and exhibits 5 times enhanced external quantum efficiency and 83 times enhanced specific detectivity(D*=3.26×10^(11)Jones).Remarkably,the unencapsulated BA_(2)MAPb_(2)I_(7)/MAPbI_(3)heterojunction is stable in ambient condition for>300 days.The Q-2D/3D heterojunction shows suppressed ion inter-diffusion due to the presence of Q-2D phase.展开更多
基金National Key R&D Program of China under Grant,Grant/Award Number:2021YFC1910601National Natural Science Foundation of China,Grant/Award Number:52104402HBIS Group Co.,Ltd Key R&D Program under Grant,Grant/Award Numbers:20210032,HG2022111。
文摘Due to their environmentally friendly nature and high energy density,direct ethanol fuel cells have attracted extensive research attention in recent decades.However,the actual Faraday efficiency of the ethanol oxidation reaction(EOR)is much lower than its theoretical value and the reaction kinetics of the EOR is sluggish due to insufficient active sites on the electrocatalyst surface.Pt/C is recognized as one of the most promising electrocatalysts for the EOR.Thus,the microscopic interfacial reaction mechanisms of the EOR on Pt/C were systematically studied in this work.In metal hydroxide solutions,hydrated alkali cations were found to bind with OH_(ad)through noncovalent interactions to form clusters and occupy the active sites on the Pt/C electrocatalyst surface,thus resulting in low Faraday efficiency and sluggish kinetics of the EOR.To reduce the negative effect of the noncovalent interactions on the EOR,a shield was made on the electrocatalyst surface using 4-trifluoromethylphenyl,resulting in twice the EOR catalytic reactivity of Pt/C.
基金the National Key Research and Development Program of China(2020YFC1909703)S&T Program of Hebei Province(21284402Z)+1 种基金Fangchenggang Key Research and Development(AB20014008)Lvliang Key Research and Development Program(2020GXZDYF7)。
文摘Since the application in fuel cell,the electrochemical adsorption of hydroxyl has received considerable attention in recent years.While most research mainly focus on the room temperature,in this paper,the electrochemical adsorption of hydroxyl in alkaline solution at high temperature was investigated.An unusual oxidation peak was observed at-0.27 V,suggesting new behavior of hydroxyl adsorption occurred.As is known two kinds of cation hydrated clusters exist in alkaline solution,(H_(2)O)_(x-1)M^(+)-H_(2)O-O_(ad)H and(H_(2)O)_xM^(+)-O_(ad)H.For K^(+)and Cs^(+),the cluster shows unstable structure due to the weak interaction between hydrated cation and OH^(-)especially at high temperature.However,For Li^(+),Na^(+)the cluster structure would be stable,as the interaction force between the hydrated cation and OH^(-)is so strong.It was revealed that the unusual oxidation peak has some relationship with the(H_(2)O)_(x-1)M^(+)-H_(2)O-O_(ad)H cluster(K^(+)and Cs^(+))absorbed at Pt electrode surface.When the temperature was raised,(H_(2)O)_(x-1)M^(+)-H_(2)O-and-O_(ad)H was disconnected,then the O_(ad)H absorbed at Pt surface got oxidated.Based on the SEM observation,it was showed the unusual electrochemical oxidation reaction would generate platinum oxides,blocking the reactive sites at Pt electrode surface,thus reducing the electrochemical reactivity of Pt electrode.Accordingly,parameters of alkaline concentration and temperature were systematically studied,it was found that increase temperature or alkaline concentration was in favor of the unusual oxidation reaction.This study provides more understanding of hydroxyl adsorption behavior at Pt electrode surface for the high temperature water solution environment.
基金Project(51104186)supported by the National Natural Science Foundation of ChinaProject(2016JJ2142)supported by the Natural Science Foundation of Hunan Province,ChinaProject supported by the Open-End Fund for the Valuable and Precision Instruments of Central South University,China
文摘To recycle vanadium and chromium from the V?Cr-bearing reducing slag,the thermodynamics of separating V(IV)and Cr(III)at 298 K was summarized in the form of potential-pH diagram and activity-pH diagram.The potential-pH diagrams of V-Mn-H2O and Cr-Mn-H2O systems show that the electrode potential of MnO2/Mn2+is higher than that of VO2+/VO2+but lower than that of Cr2O7 2-/Cr3+,which proves that it is feasible to selectively oxidize low valent vanadium using MnO2.The activity-pH diagrams of V(V)-H2O and Cr(III)-H2O systems show that the precipitation pH of V(V)is far lower than that of Cr(III),and therefore V(V)and Cr(III)can be separated through precipitation method.Based on the thermodynamic analysis,the flowsheet of recovery of vanadium and chromium from the V-Cr-bearing reducing slag is designed.
基金the National Natural Science Foundation of China(No.50274075).
文摘The separation and recovery of Ni from the copper electrolyte by crystallization of nickel ammonium sulfate double salt were studied.It is found that the solubility of copper sulfate at the same temperature is less than that of nickel sulfate,while the solubility of copper ammonium sulfate is greater than that of nickel ammonium sulfate.So,by adding(NH_(4))_(2)SO_(4),the Ni can be selectively crystallized from the copper electrolyte.By adding(NH_(4))_(2)SO_(4)at the molar ratio of(NH_(4))_(2)SO_(4)/NiSO_(4)≤0.8,and crystallizing at−15℃for 10 h,the Ni in the copper electrolyte can be crystallized in the form of Ni(NH_(4))_(2)(SO_(4))_(2)×6H_(2)O.The qualified product of NiSO_(4)×6H_(2)O can be obtained by pyrolyzing the crystals,dissolving the pyrolysis product in water,and then concentrating the dissolved solution for crystallization.The method of double salt crystallization is a clean,environmentally-friendly,cost-effective and efficient method for separating and recovering nickel from copper electrolyte.
基金financially sponsored by the Science and Technology Ministry of Jilin Province,No.200705318
文摘In this study, we aimed to explore the role of ursolic acid in the neural regeneration of the injured sciatic nerve. BALB/c mice were used to establish models of sciatic nerve injury through unilateral sciatic nerve complete transection and microscopic anastomosis at 0.5 cm below the ischial tuber-osity. The successful y generated model mice were treated with 10, 5, or 2.5 mg/kg ursolic acid via intraperitoneal injection. Enzyme-linked immunosorbent assay results showed that serum S100 protein expression level gradual y increased at 1-4 weeks after sciatic nerve injury, and significantly decreased at 8 weeks. As such, ursolic acid has the capacity to significantly increase S100 protein expression levels. Real-time quantitative PCR showed that S100 mRNA expression in the L 4-6 segments on the injury side was increased after ursolic acid treatment. In addition, the muscular mass index in the soleus muscle was also increased in mice treated with ursolic acid. Toluidine blue staining revealed that the quantity and average diameter of myelinated nerve fibers in the injured sciatic nerve were significantly increased after treatment with ursolic acid. 10 and 5 mg/kg of ursolic acid produced stronger effects than 2.5 mg/kg of ursolic acid. Our findings indicate that ursolic acid can dose-dependently increase S100 expression and promote neural regeneration in BALB/c mice fol owing sciatic nerve injury.
基金Supported by the Central South University Research Fund for Innovation-Driven Program(Grant No.2019CX024)the Natural Science Foundation of Hunan Province(Grant No.2018JJ3652)+1 种基金the China Postdoctoral Science Foundation(Grant Nos.2018M632985 and 2018T110839)the Fundamental Research Funds for the Central Universities of Central South University(Grant No.2018zzts333).
文摘Biological bipolar metaplasticities were successfully mimicked in two-dimensional(2D)MoS2 transistors via the implementation of two different MoS2 surface decorations,poly(vinyl alcohol)(PVA)and chitosan bio-polymers.Interestingly,the depressing metaplasticity was successfully mimicked when the PVA bio-polymer was used as the surface decoration layer,whereas the metaplasticity of long-term potentiation was realized when the chitosan bio-polymer was taken as the surface decoration layer.Furthermore,the electronic band structures of the 2D MoS2 devices with different surface decorations were further investigated using first-principles calculations for understanding the underlying mechanisms of such bipolar metaplasticities.These results will deepen our understanding of metaplasticity,and have great potential in neuromorphic computing applications.
基金This work was supported by the NSFC(Grant Nos.61671087,61962009 and 61003287)the Fok Ying Tong Education Foundation(Grant No.131067)+3 种基金the Major Scientific and Technological Special Project of Guizhou Province(Grant No.20183001)the Foundation of State Key Laboratory of Public Big Data(Grant No.2018BDKFJJ018)the High-quality and Cutting-edge Disciplines Construction Project for Universities in Beijing(Internet Information,Communication University of China)the Fundamental Research Funds for the Central Universities(Nos.2019XD-A02,328201915,328201917 and 328201916).
文摘Directional modulation is one of the hot topics in data security researches.To fulfill the requirements of communication security in wireless environment with multiple paths,this study takes into account the factors of reflections and antenna radiation pattern for directional modulation.Unlike other previous works,a novel multiple-reflection model,which is more realistic and complex than simplified two-ray reflection models,is proposed based on two reflectors.Another focus is a quantum genetic algorithm applied to optimize antenna excitation in a phased directional modulation antenna array.The quantum approach has strengths in convergence speed and the globe searching ability for the complicated model with the large-size antenna array and multiple paths.From this,a phased directional modulation transmission system can be optimized as regards communication safety and improve performance based on the constraint of the pattern of the antenna array.Our work can spur applications of the quantum evolutionary algorithm in directional modulation technology,which is also studied.
基金Project supported by the National Natural Science Foundation of China(Grant No.51673214)the National Key Research and Development Program of China(Grant No.2017YFA0206600)
文摘The thin film properties of organic semiconductors are very important to the device performance.Herein,non-planar vanadyl phthalocyanine(VOPc)thin films grown on rigid substrates of indium tin oxide,silicon dioxide,and flexible substrate of kapton by organic molecular beam deposition under vacuum conditions are systematically studied via atomic force microscopy and x-ray diffraction.The results clearly reveal that the morphology and grain size are strongly dependent on the substrate temperature during the process of film deposition.Meanwhile,the VOPc films with the structure of phase I or phase II can be modulated via in situ annealing and post-annealing temperature.Furthermore,the crystalline structure and molecular orientation of vapor-deposited VOPc can be controlled using molecular template layer 3,4,9,10-perylenetetracarboxylic dianhydride(PTCDA),the VOPc film of which exhibits the phase I structure.The deep understanding of growth mechanism of non-planar VOPc film provides valuable information for controlling structure-property relationship and accelerates the application in electronic and optoelectronic devices.
基金Project supported by the National Natural Science Foundation of China(Grant No.51673214)the National Key Research and Development Program of China(Grant No.2017YFA0206600)。
文摘The morphology and interface of perovskite film are very important for the performance of perovskite solar cells(PSCs).The quality of perovskite film,fabricated via two-step spin-coating process,is significantly influenced by the morphology and crystallinity of PbI2 film.With the addition of additive dimethyl sulfoxide(DMSO)into the PbI2 precursor,the roughness and trap-state density of perovskite film have been significantly reduced,leading to the excellent contact between perovskite layer and subsequent deposited carrier transport layer.Accordingly,the planar heterojunction PSCs with an architecture of ITO/SnO2/perovskite/PTAA/Ag show an efficiency up to 19.02%.Furthermore,PSCs exhibit promising stability in air with a humidity of ~45%,and retain 80% of initial efficiency after being exposed to air for 400 h without any encapsulation.
基金National Science and Technology Major Project(No.2018ZX10101003-001-009)theNational Natural Science Foundation of China(No.81960002,81860002)School of Tropical Medicine and Laboratory Medicine,Hainan Medical University/Research Cultivation Fund(No.1021/XPY180017)。
文摘Objective:To investigate the epidemic characteristics of multidrug resistant tuberculosis in Hainan,China,to provide basic information and theories for the prevention and control of multidrug resistant tuberculosis.Methods:A retrospective descriptive epidemiological study was conducted.Data of multidrug resistant tuberculosis in Hainan Island from January 1,2014 to December 31,2019 were collected for statistical analysis.The counting data were described by frequency(percentage),and the measurement data were described by mean±standard deviation.Chi square test was used to compare the differences between different groups.If P<0.05,the difference was statistically significant.Results:From 2014 to 2019,the multidrug resistant rate of tuberculosis in Hainan Island was 24.9%(369/1484),8.0%(63/791)in newly-treated tuberculosis,and 44.2%(306/693)in retreatedmultidrug resistant rate of tuberculosis in Hainan Island was 24.9%(369/1484),8.0%(63/791)in newly-treatedtuberculosis,and 44.2%(306/693)in retreated tuberculosis.The multidrug resistant rate of newly-treated tuberculosis decreased by 0.05%per year,while that of retreated tuberculosis increased by 0.03%per year.multidrug resistant tuberculosis was mainly distributed in the city of Haikou(83 cases),Danzhou(44 cases),Wenchang(42 cases),Wanning(37 cases)and Dongfang(32 cases),accounting for 64.5%of all multidrug resistant tuberculosis.Among 369 multidrug resistant tuberculosis,81.0%were male.The proportion of newly-treated cases was 17.1%(63/369),while the proportion of retreated cases was 82.9%(306/369),which was significantly higher than that of newly-treated cases.The multidrug resistant rate of tuberculosis in different years was different.Conclusion:The drug resistance rate of tuberculosis in Hainan Island is higher than the national average level,which needs attention.The epidemiological characteristics of multidrug resistant tuberculosis with different treatment history were different.
基金National Science and Technology Major Project of China(No.2018Z X10101003-001-009)。
文摘Mosquitoes are an important medical insect and play a very important role in the process of biologically vector infectious diseases.A large number of bacterial communities are colonized in their intestines.In the process of interaction and symbiosis with mosquitoes,the bacterial community is in many ways.The life activities of mosquitoes have a significant impact.This article reviews the population structure of the mosquito intestinal flora,influencing factors,and the regulation of mosquito vector efficacy by the flora.
文摘Based on case study of the practice of smart city development around the world,which has achieved a lot to make our life more convenient,through analysis of advantages and disadvantages,conclusion of some principles could be reached in a qualitative way.After studying the policy and economy environment of China,this paper concludes some features,identifies opportunities and challenges for smart city under the background of“The Belt and Road Initiative”,and provides suggestions on the development of China.
基金supported by grants from the National Major Special Project of Breeding for Genetically Modified Organisms in China(No.2016ZX08012-005,2016ZX08012-003)the Agricultural Science and Technology Innovation Program of Chinese Academy of Agricultural Sciences,China.
文摘To develop a simple and fast method for screening genetically modified ingredients from processing by-product and waste,direct quantitative PCR(qPCR)kit-Taqman which omitting multi genomic DNA preparing steps was developed in this study.A total of 18 oil crop processing by-products and wastes including 10 soybean and 8 cotton materials were collected from food processing factories.Compared with 2 commercial direct qPCR kits,conditions of DNA releasing procedure and PCR amplification were optimized.Element screening was performed at the initial step of genetically modified(GM)ingredient testing procedure via direct qPCR.GM event identification was carried out in positive samples by initial screening.Totally 5 screening elements(P–35S,T-NOS,Cp4-epsps,bar and pat)for soybean materials and 6 screening elements(P–35S,T-NOS,NPTII,Cry1Ac,bar and pat)for cotton samples were detected.In GM event identification,MON531 and MON1445 were found in cotton materials.Results were further confirmed by real-time PCR with DNA extraction and purification.The direct qPCR system proposed by this research was convenient for rapid screening and identification of GM ingredients in oil crop primary by-product and waste.
文摘Cultivating students＇ autonomous learning ability is the inevitable trend of modern education in the information age and lifelong learning. This paper briefly introduces the concept of Autonomous English learning, and puts forward how to cultivate students＇ autonomous learning ability. Students activety participate in the learning process and experience/earning process can greatly promote the learning effect. The cultivation of autonomous learning ability is an important guarantee for success in learning English. Therefore, how to improve the autonomous learning ability of English majors is a topic worth exploring. The experimental results show that these strategies can improve students＇ autonomous learning awareness, students ＇ learning initiative and independence, and the ability of autonomous learning is gradually improving
文摘Side-channel attacks based on supervised learning require that the attacker have complete control over the cryptographic device and obtain a large number of labeled power traces.However,in real life,this requirement is usually not met.In this paper,an attack algorithm based on collaborative learning is proposed.The algorithm only needs to use a small number of labeled power traces to cooperate with the unlabeled power trace to realize the attack to cryptographic device.By experimenting with the DPA contest V4 dataset,the results show that the algorithm can improve the accuracy by about 20%compared with the pure supervised learning in the case of using only 10 labeled power traces.
基金supported by GuangDong Basic and Applied Basic ResearchFoundation(2021A1515111109 to LYZ)the National Natural ScienceFoundation of China(82371632 to YXT)China Postdoctoral ScienceFoundation(2021M703747 to LYZ).
文摘Ex vivo tissue culture of the human corpus cavernosum(cc)can be used to explore the tissue structural changes and complex signaling networks.At present,artificial Cc-like tissues based on acellular or three-dimensional(3D)-printed scaffolds are used to solve the scarcity of primary penis tissue samples.However,inconvenience and high costs limit the wide application of such methods.Here,we describe a simple,fast,and economical method of constructing artificial CC-like tissue.Human Cc fibroblasts(FBs),endothelial cells(ECs),and smooth muscle cells(SMCs)were expanded in vitro and mixed with Matrigel in specific proportions.A large number of bubbles were formed in the mixture by vortexing combined with pipette blowing,creating a porous,spongy,and spatial structure.The Cc FBs produced a variety of signaling factors,showed multidirectional differentiation potential,and grew in a 3D grid in Matrigel,which is necessary for CC-like tissue to maintain a porous structure as a cell scaffold.Within the C-like tissue,ECs covered the surface of the lumen,and SMCs were located inside the trabeculae,similar to the structure of the primary Cc.Various cell components remained stable for 3 days in vitro,but the EC content decreased on the 7th day.Wingless/integrated(WNT)signaling activation led to lumen atrophy and increased tissue fibrosis in CC-like tissue,inducing the same changes in characteristics as in the primary Cc.This study describes a preparation method for human artificial cC-like tissue that may provide an improved experimental platform for exploring the function and structure of the cC and conducting drug screening for erectile dysfunction therapy.
基金the National Natural Science Foundation of China(Nos.52273202,62104261,51673218,and 62004066)the National Key Research and Development Program of China(No.2022YFB3803300)+4 种基金the Natural Science Program of Xinjiang Uygur Autonomous Region(No.2023D01D03)the Major Scientific and Technological Project of Changsha(No.kq2301002)the Program of Hundreds of Talents of Hunan Province and Changsha Municipal Natural Science Foundation(No.KQ2007027)the National Key Research and Development Program of China(No.2023YFE0116800)the Beijing Natural Science Foundation(No.IS23037).
文摘Although numerous metal halide perovskite materials have been investigated in the field of optoelectronic,the development of perovskite heterojunctions with exotic structures is still rare.Herein,we report the epitaxial growth of quasi-two-dimensional(Q-2D)perovskites on methylammonium lead iodide(MAPbI_(3))single crystals to form perovskite heterojunctions with interfacial bonding.The MAPbI_(3)adjacent to epitaxial Q-2D perovskite shows blue shifted photoluminescence with shortened lifetime,which becomes significant with the reduced layer number of the Q-2D perovskites.Our findings suggest the presence of an interfacial strain gradient leading to enhanced photocarrier separation.Accordingly,compared to the MAPbI_(3)single crystal detector,the BA_(2)MAPb_(2)I_(7)/MAPbI_(3)(BA:n-butylamine)heterojunction-based photodetector demonstrates a bandpass detecting property and exhibits 5 times enhanced external quantum efficiency and 83 times enhanced specific detectivity(D*=3.26×10^(11)Jones).Remarkably,the unencapsulated BA_(2)MAPb_(2)I_(7)/MAPbI_(3)heterojunction is stable in ambient condition for>300 days.The Q-2D/3D heterojunction shows suppressed ion inter-diffusion due to the presence of Q-2D phase.
