Central retinal artery occlusion(CRAO)is an acute ophthalmic emergency,characterized by sudden vision loss due to retinal ischemia in areas corresponding to arterial occlusion sites.Diagnosis primarily relies on fundu...Central retinal artery occlusion(CRAO)is an acute ophthalmic emergency,characterized by sudden vision loss due to retinal ischemia in areas corresponding to arterial occlusion sites.Diagnosis primarily relies on fundus fluorescein angiography(FFA)and optical coherence tomography(OCT),which show delayed retinal artery filling time hours to days after occlusion and increased hyperreflectivity of the inner retina.展开更多
Oxygen-rich porous carbons are promising candidates for the carbon-based cathodes of zinc ion hybrid capacitors(ZIHCs).Potassium activation is a traditional and effective way to prepare oxygen-rich porous carbons.Effi...Oxygen-rich porous carbons are promising candidates for the carbon-based cathodes of zinc ion hybrid capacitors(ZIHCs).Potassium activation is a traditional and effective way to prepare oxygen-rich porous carbons.Efficient potassium activation is the key to develop high-performance oxygen-rich porous carbon cathodes.Herein,the alkali lignin,extracted from eucalyptus wood by geopolymer-assisted low-alkali pretreatment,is used to prepare oxygen-rich lignin-derived porous carbons(OLPCs)through KOH activation and K_(2)CO_(3)activation at 700-900℃.KOH activation constructs a hierarchical micro-mesoporous structure,while K_(2)CO_(3)activation constructs a microporous structure.Furthermore,K_(2)CO_(3)activation could more efficiently construct active oxygen(C=O)species than KOH activation.The OLPCs prepared by KOH/K_(2)CO_(3)activations at 800℃show the highest microporosity(78.4/87.7%)and C=O content(5.3/8.0 at.%).Due to that C=O and micropore adsorb zinc ions,the OLPCs prepared by K_(2)CO_(3)activation at 800℃with higher C=O content and microporosity deliver superior capacitive performance(256 F g^(-1)at 0.1 A g^(-1))than that by KOH activation at 800℃(224 F g^(-1)at 0.1 A g^(-1)),and excellent cycling stability.This work provides a new insight into the sustainable preparation of oxygenrich porous carbon cathodes through efficient potassium activation for ZIHCs.展开更多
Mesenchymal stromal cell transplantation is an effective and promising approach for treating various systemic and diffuse diseases.However,the biological characteristics of transplanted mesenchymal stromal cells in hu...Mesenchymal stromal cell transplantation is an effective and promising approach for treating various systemic and diffuse diseases.However,the biological characteristics of transplanted mesenchymal stromal cells in humans remain unclear,including cell viability,distribution,migration,and fate.Conventional cell tracing methods cannot be used in the clinic.The use of superparamagnetic iron oxide nanoparticles as contrast agents allows for the observation of transplanted cells using magnetic resonance imaging.In 2016,the National Medical Products Administration of China approved a new superparamagnetic iron oxide nanoparticle,Ruicun,for use as a contrast agent in clinical trials.In the present study,an acute hemi-transection spinal cord injury model was established in beagle dogs.The injury was then treated by transplantation of Ruicun-labeled mesenchymal stromal cells.The results indicated that Ruicunlabeled mesenchymal stromal cells repaired damaged spinal cord fibers and partially restored neurological function in animals with acute spinal cord injury.T2*-weighted imaging revealed low signal areas on both sides of the injured spinal cord.The results of quantitative susceptibility mapping with ultrashort echo time sequences indicated that Ruicun-labeled mesenchymal stromal cells persisted stably within the injured spinal cord for over 4 weeks.These findings suggest that magnetic resonance imaging has the potential to effectively track the migration of Ruicun-labeled mesenchymal stromal cells and assess their ability to repair spinal cord injury.展开更多
The healing of critical-sized bone defects(CSD)remains a challenge in orthopedic medicine.In recent years,scaffolds with sophisticated microstructures fabricated by the emerging three-dimensional(3D)printing technolog...The healing of critical-sized bone defects(CSD)remains a challenge in orthopedic medicine.In recent years,scaffolds with sophisticated microstructures fabricated by the emerging three-dimensional(3D)printing technology have lighted up the treatment of the CSD due to the elaborate microenvironments and support they may build.Here,we established a magnesium oxide-reinforced 3D-printed biocompos-ite scaffold to investigate the effect of magnesium-enriched 3D microenvironment on CSD repairing.The composite was prepared using a biodegradable polymer matrix,polycaprolactone(PCL),and the disper-sion phase,magnesium oxide(MgO).With the appropriate surface treatment by saline coupling agent,the MgO dispersed homogeneously in the polymer matrix,leading to enhanced mechanical performance and steady release of magnesium ion(Mg^(2+))for superior cytocompatibility,higher cell viability,advanced osteogenic differentiation,and cell mineralization capabilities in comparison with the pure PCL.The in-vivo femoral implantation and critical-sized cranial bone defect studies demonstrated the importance of the 3D magnesium microenvironment,as a scaffold that released appropriate Mg^(2+) exhibited remarkably increased bone volume,enhanced angiogenesis,and almost recovered CSD after 8-week implantation.Overall,this study suggests that the magnesium-enriched 3D scaffold is a potential candidate for the treatment of CSD in a cell-free therapeutic approach.展开更多
Diffusion bonding of refractory Nb–Si-based alloy was performed with Ni/Al and Ti/Al nanolayers under the condition of 1473 K/30 MPa/60 min.The NbSS/Nb5Si3 in situ composite with the nominal composition of Nb–22 Ti...Diffusion bonding of refractory Nb–Si-based alloy was performed with Ni/Al and Ti/Al nanolayers under the condition of 1473 K/30 MPa/60 min.The NbSS/Nb5Si3 in situ composite with the nominal composition of Nb–22 Ti–16 Si–3 Cr–3 Al–2 Hf was used as the parent material.The joint microstructures were examined by using a scanning electron microscope equipped with an X-ray energy dispersive spectrometer.Shear test was conducted for the bonded joints at room temperature.Within the joint bonded with Ni/Al multilayer,element diffusion occurred between the base metal and the nanolayer,with the reaction products of AlNb2+Ni3 Al,NiAl and AlNi2 Ti phases.The average shear strength was 182 MPa.While using Ti/Al multilayer,the interface mainly consisted of TiAl,(Ti,Nb)Al and(Ti,Nb)2 Al phases,and the corresponding joints exhibited an increased strength of 228 MPa.In this case,the fracture mainly took place in the TiAl phase and presented a typical brittle characteristic.展开更多
The Advanced Space-based Solar Observatory(ASO-S) mission aims to explore the two most spectacular eruptions on the Sun: solar flares and coronal mass ejections(CMEs), and their magnetism.For the study of CMEs, the pa...The Advanced Space-based Solar Observatory(ASO-S) mission aims to explore the two most spectacular eruptions on the Sun: solar flares and coronal mass ejections(CMEs), and their magnetism.For the study of CMEs, the payload Lyman-alpha Solar Telescope(LST) has been proposed. It includes a traditional white-light coronagraph and a Lyman-alpha coronagraph which opens a new window to CME observations. Polarization measurements taken by white-light coronagraphs are crucial for deriving fundamental physical parameters of CMEs. To make such measurements, there are two options for a Stokes polarimeter which have been applied by existing white-light coronagraphs for space missions. One uses a single or triple linear polarizer, the other involves both a half-wave plate and a linear polarizer. We find that the former option is subject to less uncertainty in the derived Stokes vector propagating from detector noise.The latter option involves two plates which are prone to internal reflections and may have a reduced transmission factor. Therefore, the former option is adopted as our Stokes polarimeter scheme for LST. Based on the parameters of the intended linear polarizer(s) colorPol provided by CODIXX and the half-wave plate 2-APW-L2-012 C by Altechna, it is further shown that the imperfect maximum transmittance of the polarizer significantly increases the variance amplification of Stokes vector by at least about 50% when compared with the ideal case. The relative errors of Stokes vector caused by the imperfection of colorPol polarizer and the uncertainty due to the polarizer assembly in the telescope are estimated to be about 5%. Among the considered parameters, we find that the dominant error comes from the uncertainty in the maximum transmittance of the polarizer.展开更多
Atmospheric pressure plasma jet(APPJ)was used to clean nitrogen-containing carbon films(C–N)fabricated by plasma-assisted chemical vapor deposition method employing the plasma surface interaction linear device at Sic...Atmospheric pressure plasma jet(APPJ)was used to clean nitrogen-containing carbon films(C–N)fabricated by plasma-assisted chemical vapor deposition method employing the plasma surface interaction linear device at Sichuan University(SCU-PSI).The properties of the contaminated films on the surface of pristine and He-plasma pre-irradiated tungsten matrix,such as morphology,crystalline structure,element composition and chemical structure were characterized by scanning electron microscopy,grazing incidence x-ray diffraction and x-ray photoelectron spectroscopy.The experimental results revealed that the removal of C–N film with a thickness of tens of microns can be realized through APPJ cleaning regardless of the morphology of the substrates.Similar removal rates of 16.82 and 13.78μm min^(-1)were obtained for C–N films deposited on a smooth pristine W surface and rough fuzz-covered W surface,respectively.This is a remarkable improvement in comparison to the traditional cleaning method.However,slight surface oxidation was found after APPJ cleaning,but the degree of oxidation was acceptable with an oxidation depth increase of only 3.15 nm.Optical emission spectroscopy analysis and mass spectrometry analysis showed that C–N contamination was mainly removed through chemical reaction with reactive oxygen species during APPJ treatment using air as the working gas.These results make APPJ cleaning a potentially effective method for the rapid removal of C–N films from the wall surfaces of fusion devices.展开更多
Traditional microtubule inhibitors fail to significantly enhance+e effect of colorectal cancer;hence,new and efficient strategies are necessary.In+is study,a supramolecular nanoreactor(DOC@TA-Fe^(3+))based on tannic a...Traditional microtubule inhibitors fail to significantly enhance+e effect of colorectal cancer;hence,new and efficient strategies are necessary.In+is study,a supramolecular nanoreactor(DOC@TA-Fe^(3+))based on tannic acid(TA),iron ion(Fe^(3+)),and docetaxel(DOC)wi+microtubule inhibition,reactive oxygen species(ROS)generation,and gluta+ione peroxidase 4(GPX4)inhibition,is prepared for ferroptosis/apoptosis treatment.After internalization by CT26 cells,+e DOC@TA-Fe^(3+)nanoreactor escapes from+e lysosomes to release payloads.+e subsequent Fe^(3+)/Fe^(2+)conversion mediated by TA reducibility can trigger+e Fenton reaction to enhance+e ROS concentration.Additionally,Fe^(3+)can consume gluta+ione to repress+e activity of GPX4 to induce ferroptosis.Meanwhile,+e released DOC controls microtubule dynamics to activate+e apoptosis pa+way.+e superior in vivo antitumor efficacy of DOC@TA-Fe^(3+)nanoreactor in terms of tumor grow+inhibition and improved survival is verified in CT26 tumor-bearing mouse model.+erefore,+e nanoreactor can act as an effective apoptosis and ferroptosis inducer for application in colorectal cancer+erapy.展开更多
Based on ab initio density functional theory calculations,we demonstrate that two carbon-doped boron nitride analog ofα-graphyne structures,B_(3) C_(2) N_(3)) and BC_(6) N monolayers,are two-dimensional direct wide b...Based on ab initio density functional theory calculations,we demonstrate that two carbon-doped boron nitride analog ofα-graphyne structures,B_(3) C_(2) N_(3)) and BC_(6) N monolayers,are two-dimensional direct wide band gap semiconductors,and there are two inequivalent valleys in the vicinities of the vertices of their hexagonal Brillouin zones.Besides,B_(3)C_(2)N_(3) and BC_(6)N monolayers exhibit relatively high carrier mobilities,and their direct band gap feature is robust against the biaxial strain.More importantly,the energetically most favorable B_(3)C_(2)N_(3) and BC_(6)N bilayers also have direct wide band gaps,and valley polarization could be achieved by optical helicity.Finally,we show that BC_(6) N monolayer might have high efficiency in photo-splitting reactions of water,and a vertical van der Waals heterostructure with a type-Ⅱenergy band alignment could be designed using B_(3)C_(2)N_(3)and BC_(6)N monolayers.All the above-mentioned characteristics make B_(3)C_(2)N_(3) and BC_(6)N monolayers,bilayers,and their heterostructures recommendable candidates for applications in valleytronic devices,metal-free photocatalysts,and photovoltaic cells.展开更多
The formation process of aromatic hydrocarbon tar during the pyrolysis process of biomass components of cel-lulose and lignin was carried out by quantum chemical calculation based on density functional theory method B...The formation process of aromatic hydrocarbon tar during the pyrolysis process of biomass components of cel-lulose and lignin was carried out by quantum chemical calculation based on density functional theory method B3LYP/6-31G++(d,p).5 Hydroxymethylfurfural was chosen as the model compound of cellulose and hemicel-lulose,and syringa ldehyde was chosen as the model compound of lignin.The calculation results show that the formation process of cellulose monocyclic aromatic hydrocarbon tar is the conversion process of benzene ring from furan ring,and the highest reaction energy barrier appears in the process of decarbonylation,which is 370.8 kJ/mol.The formation of lignin monocyclic aromatic hydrocarbon tar is mainly the process of side chains removal and the formation of phenol,The highest reaction energy barrier appears in the process of decarbonyla-tion,which is 374.9 kJ/mol.The reaction mechanism of phenanthrene formation from naphthalene was selected as the formation of cellulose and lignin polycydic aromatic hydrocarbon tar.The calculation results show that he total barrier of the pathway that naphthalene dehydrogenates to form naphthalene free radicals and then reacts with ethylene twice by addition action,finally occurs cydization reactions and isomerizes to produce phenan-threne is lowest,that is 38.6 kJ/mol.So it is proved that the evolution of tar is the process of deoxygenation and cyclization with the increase of the temperature from a theoretical point of view.展开更多
Oral iron supplements such as ferrous iron salts are major treatment agents for iron deficiency anemia(IDA)due to the convenience of large dose administration and good patient compliance.However,the gastrointestinal a...Oral iron supplements such as ferrous iron salts are major treatment agents for iron deficiency anemia(IDA)due to the convenience of large dose administration and good patient compliance.However,the gastrointestinal adverse impact caused by Fe2+stimulus and low bioavailability severely impedes its therapeutic effects.In recent years,it has been found that nano iron⁃based nanoparticles with high surface⁃to⁃volume ratio and low iron ion leakage can alleviate the toxic effect and improve the gastrointestinal absorbance.For further clinical development,nano materials need to meet the pharmaceutical quality demand.Carboxymethyl cellulose(CMC)is a significant pharmaceutical ingredient applied in approved drug formulations,and polyglucosorbitol carboxymethylether(PSC)has been utilized in iron⁃based nanomedicine ferumoxytol synthesis,both of which can be firmly anchored on iron oxide by carboxyl chelation.In this work,iron oxide nanoparticles(NPs)modified with CMC were designed and synthesized,and the structure composition and physicochemical properties were distinctly characterized.Oral supplement effects on rat IDA were investigated and compared with other recently reported iron supplements including NPs modified with PSC.Results show that the oral nano iron supplement achieved the recovery of hemoglobin and serum iron level in only two weeks with high safety.The nano iron oxide modified with pharmaceutical excipients provides new potential approach for oral iron supplement available in clinics.展开更多
New observations of auroras based on the wide-field aurora imager(WAI)onboard Fengyun-3D(FY-3D)satellite are exhibited in this paper.Validity of the WAI data is analyzed by comparing auroral boundaries derived from WA...New observations of auroras based on the wide-field aurora imager(WAI)onboard Fengyun-3D(FY-3D)satellite are exhibited in this paper.Validity of the WAI data is analyzed by comparing auroral boundaries derived from WAI observations with results obtained from data collected by the Special Sensor Ultraviolet Spectrographic Imager(SSUSI)aboard the Defense Meteorological Satellite Program(DMSP F18).Dynamic variations of the aurora with the solar wind,interplanetary magnetic field(IMF)parameters,and the SYM-H index are also investigated.The comparison of auroral boundaries indicates that the WAI data are morphologically valid and suitable to the study of auroral dynamics.Effective responses to solar wind parameters indicate that the WAI data can be useful to monitor and predict the Earth’s space weather.Since the configuration of aurora is a good indicator of the solar wind–magnetosphere–ionosphere(SW-M-I)coupling system,and can reflect the disturbance of the space environment,the WAI will provide important data to help us to study the physical processes in space.展开更多
In China, although improvements to the pesticide registration process have been made in la thirty years, no occupational exposure data are required to obtain a commercial license for pesticide product. Consequently, n...In China, although improvements to the pesticide registration process have been made in la thirty years, no occupational exposure data are required to obtain a commercial license for pesticide product. Consequently, notably little research has been conducted to establish a exposure assessment procedure in China. The present study monitored the potential derm operator exposure from knapsack electric sprayer wheat field application of imidacloprid Liaocheng City, Shandong Province and in Xinxiang City, Henan Province, China, usin whole-body dosimetry. The potential inhalation exposure was determined using a person air pump and XAD-2 sample tubes. The analytical method was developed and validate including such performance parameters as limits of detection and quantification, linear rang recovery and precision. The total potential dermal and inhalation exposures were 14.20, 16.815.39 and 20.78 mL/hr, respectively, for the four operators in Liaocheng and Xinxian corresponding to 0.02% to 0.03% of the applied volume of spray solution. In all trials, the low part（thigh, lower leg） of the body was the most contaminated, accounting for approximate76% to 88% of the total exposure. The inhalation exposure was less than 1% of the tot exposure. Such factors as the application pattern, crop type, spray equipment, operat experience and climatic conditions have been used to explain the exposure distribution ov the different parts of the body. As indicated by the calculated Margin of Exposure, the typic wheat treatment scenarios when a backpack sprayer was used are considered to be safe terms of imidacloprid exposure.展开更多
Objective： To evaluate the effect of transplanting bone marrow-derived mesenchymal stem cells （BM-MSCs） or adenovirus5- hepatocyte growth factor（Ad5-HGF） via non-infarct-related artery injection in swine myocardi...Objective： To evaluate the effect of transplanting bone marrow-derived mesenchymal stem cells （BM-MSCs） or adenovirus5- hepatocyte growth factor（Ad5-HGF） via non-infarct-related artery injection in swine myocardial infarction models. Methods：BMMSCs were obtained from swine bone marrow and expanded in vitro to a purity of 〉50%. A myocardial infarction（MI） was created by ligating the distal left anterior descending artery in swine. Either BM-MSCs （5 × 10^6/ml） or Ad5-HGF （4 × 10^9 pfu） were transfused via the right coronary artery （non-infarcted artery） four weeks after MI. Gate-controled cardiac perfusion imaging was performed at the end of four and seven weeks after LAD ligation, to evaluate heart function and cardiac perfusion. Morphologic and histologic characteristics of the hearts were also studied. Results： （1）The gate-controlled cardiac perfusion imaging showed that the improvement in LVEF was greater in both treatment groups than in control group at the 4^th weeks. （2）In both treatment groups, capillary density was significantly higher than that of control group（P 〈 0.05）. Conclusion ：BM-MSCs or Ad5-HGF transplantation via non-infarcted artery administration can stimulate angiogenesis and improve heart function, but there was no difference in therapeutic efficacy between BM-MSCs and Ad5-HGF.展开更多
In the present paper, we consider the problem {-△u=u^(β_(1))|■u|^(β_(2)),in Ω,u=0,on ■Ω,u>0,in Ω,(0.1) where β_(1), β_(2) > 0 and β_(1) + β_(2) < 1, and Ω is a convex domain in R~n. The existence...In the present paper, we consider the problem {-△u=u^(β_(1))|■u|^(β_(2)),in Ω,u=0,on ■Ω,u>0,in Ω,(0.1) where β_(1), β_(2) > 0 and β_(1) + β_(2) < 1, and Ω is a convex domain in R~n. The existence, uniqueness,regularity and (2-β_(2))/(1-β_(1)-β_(2))-concavity of the positive solutions of the problem(0.1) are proven.展开更多
Extreme ultraviolet(EUV)observations are widely used in solar activity research and space weather forecasting since they can observe both the solar eruptions and the source regions of the solar wind.Flat field process...Extreme ultraviolet(EUV)observations are widely used in solar activity research and space weather forecasting since they can observe both the solar eruptions and the source regions of the solar wind.Flat field processing is indispensable to remove the instrumental non-uniformity of a solar EUV imager in producing high-quality scientific data from original observed data.FengYun-3E(FY-3E)is a meteorological satellite operated in a Sunsynchronous orbit,and the routine EUV imaging data from the Solar X-ray and Extreme Ultraviolet Imager(X-EUVI)onboard FY-3E has the characteristic of concentric rotation.Taking advantage of the concentric rotation,we propose a post-hoc flat field measurement method for its EUV 195A channel in this paper.This method removes the small-scale and time-varying component of coronal activities by taking the median value for each pixel along the time axis of a concentric rotation data cube,and then derives the large-scale and invariable component of the quiet coronal radiation,and finally generates a flat field image.The flat field can be generated with cadences from hundreds of minutes(one orbit)to several days.Higher flat field accuracy can be achieved by employing more data.Further analysis shows that our method is able to measure the instrumental spot-like nonuniformity possibly caused by contamination on the detector,which mostly disappears after the in-orbit selfcleaning process.It can also measure the quasi-periodic grid-like non-uniformity,possibly from the obscuration of the support mesh on the rear filter.After flat field correction,these instrumental non-uniformities from the original data are effectively removed.Moreover,the X-EUVI 195A data after dark and flat field corrections are consistent with the 193A imaging data from the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory,verifying the suitability of the method.The post-hoc method does not occupy observation time,which is advantageous for space weather operations.Our method is not only suitable for FY-3E/X-EUVI but also a candidate method for the flat field measurement of future solar EUV telescopes.展开更多
This paper interrogates the impact of policy events on the efficiency of carbon market in China.The analysis covers five piloting emission trading schemes(Beijing, Shanghai, Guangdong,Shenzhen and Hubei), particularly...This paper interrogates the impact of policy events on the efficiency of carbon market in China.The analysis covers five piloting emission trading schemes(Beijing, Shanghai, Guangdong,Shenzhen and Hubei), particularly focusing on Guangdong pilot for its weak form efficiency and the richness of policy events. Twenty-five policy events between 2014 and 2016 are categorized into seven groups. The efficiency test indicates that only Guangdong ETS has reached weak form efficiency. After exploring the policy events occurred in Guangdong ETS, it finds that although a clear long-term climate policy has been set up over the country, China's carbon market still has a conservative risk appetite and its governing institutions still needs further development. The policy makers need to be aware of and avoid the negative impacts of policy events to the market evolvement, by introducing effective consultancy process with the stakeholders and nurturing market expectations in the long run. We also find that events like allowance auctions have considerably less impacts than previously expected and argue that auction approach should be considered a preferable option over a free allocation system in the future policy design.展开更多
Carbonate electrolytes are one of the most desirable electrolytes for high-energy lithium-sulfur batteries(LSBs)because of their successful implementation in commercial Li-ion batteries.The low-polysulfide-solubility ...Carbonate electrolytes are one of the most desirable electrolytes for high-energy lithium-sulfur batteries(LSBs)because of their successful implementation in commercial Li-ion batteries.The low-polysulfide-solubility feature of some carbonate solvents also makes them very promising for overcoming the shuttle effects of LSBs.However,regular sulfur electrodes experience undesired electrochemical mechanisms in carbonate electrolytes due to side reactions.In this study,we report a catalytic redox mechanism of sulfur in propylene carbonate(PC)electrolyte based on a compari-son study.The catalytic mechanism is characterized by the interactions between polysulfides and dual N/O functional groups on the host carbon,which largely prevents side reactions between polysulfides and the carbonate electrolyte.Such a mechanism coupled with the low-polysulfide-solubility feature leads to stable cycling of LSBs in PC electrolyte.Favorable dual N/O functional groups are identified via a density functional theory study.This work provides an alternative route for enabling LSBs in carbonate electrolytes.展开更多
The net erosion yield of CX-2002U carbon fiber composites under high-flux low-temperature hydrogen plasma is investigated using a linear plasma device.It is found that the net erosion yield decreases rapidly first,and...The net erosion yield of CX-2002U carbon fiber composites under high-flux low-temperature hydrogen plasma is investigated using a linear plasma device.It is found that the net erosion yield decreases rapidly first,and then tends to saturate with the increase of hydrogen–plasma flux.When the temperature of the sample eroded by hydrogen plasma is above 300°C,the hybridization of electrons outside the carbon atom would change.Then the carbon atoms combine with hydrogen atoms to form massive spherical nanoparticles of hydrocarbon compounds and deposit on the surface at the flux condition of 1.77×10^(22) m^(−2)·s^(−1).Under the irradiation of hydrogen plasma loaded with negative bias,the surface morphology of the matrix carbon is changed dramatically.Moreover,the energy dependence of mass loss does not increase in proportion to the increase of hydrogen–plasma energy,but reaches a peak around 20 V negative bias voltage.Based on the analysis of different samples,it can be concluded that the enhancement of energy could make a contribution to chemical erosion and enlarge the size of pores existing on the surface.展开更多
Steady high-flux helium(He)plasma with energy ranging from 50 eV to 90 eV is used to fabricate a fiber-form nanostructure called fuzz on a polycrystalline molybdenum(Mo)surface.Enhanced hydrogen(H)pulsed plasma in a w...Steady high-flux helium(He)plasma with energy ranging from 50 eV to 90 eV is used to fabricate a fiber-form nanostructure called fuzz on a polycrystalline molybdenum(Mo)surface.Enhanced hydrogen(H)pulsed plasma in a wide power density range of 12 MW/m^(2)-35 MW/m^(2)is subsequently used to bombard the fuzzy Mo,thereby simulating the damage of edge localized mode(ELM)to fuzz.The comparisons of surface morphologies,crystalline structures,and optical reflectivity between the original Mo and the Mo treated with various He^(+)energy and transient power densities are performed.With the increase of He ion energy,the Mo nano-fuzz evolved density is enlarged due to the decrease of filament diameter and optical reflectivity.The fuzz-enhanced He release should be the consequence of crystalline growth and the lattice shrinkage inside the Mo-irradiated layers(^(2)00 nm).The fuzz induced by lower energy experiences more severe melting damage and dust release under the condition of the identical transient H plasma-bombardment.The H and He are less likely to be trapped due to aggravated melting evidenced by the enhanced crystalline size and distinct lattice shrinkage.As the transient power density rises,the thermal effect is enhanced,thereby causing the fuzz melting loss to aggravate and finally to completely disappear when the power density exceeds 21 MW/m^(2).Irreversible grain expansion results in huge tensile stress,leading to the observable brittle cracking.The effects of transient thermal load and He ion energy play a crucial role in etching Mo fuzz during ELM transient events.展开更多
基金Supported by National Natural Science Foundation of China(No.82070991).
文摘Central retinal artery occlusion(CRAO)is an acute ophthalmic emergency,characterized by sudden vision loss due to retinal ischemia in areas corresponding to arterial occlusion sites.Diagnosis primarily relies on fundus fluorescein angiography(FFA)and optical coherence tomography(OCT),which show delayed retinal artery filling time hours to days after occlusion and increased hyperreflectivity of the inner retina.
基金supported by the National Natural Science Foundation of China(22408061 and 22468005)Program for Introducing High-Level Talents from Guangxi University,and Guangxi Key Laboratory of Petrochemical Resource Processing and Process Intensification Technology(2023Z014).
文摘Oxygen-rich porous carbons are promising candidates for the carbon-based cathodes of zinc ion hybrid capacitors(ZIHCs).Potassium activation is a traditional and effective way to prepare oxygen-rich porous carbons.Efficient potassium activation is the key to develop high-performance oxygen-rich porous carbon cathodes.Herein,the alkali lignin,extracted from eucalyptus wood by geopolymer-assisted low-alkali pretreatment,is used to prepare oxygen-rich lignin-derived porous carbons(OLPCs)through KOH activation and K_(2)CO_(3)activation at 700-900℃.KOH activation constructs a hierarchical micro-mesoporous structure,while K_(2)CO_(3)activation constructs a microporous structure.Furthermore,K_(2)CO_(3)activation could more efficiently construct active oxygen(C=O)species than KOH activation.The OLPCs prepared by KOH/K_(2)CO_(3)activations at 800℃show the highest microporosity(78.4/87.7%)and C=O content(5.3/8.0 at.%).Due to that C=O and micropore adsorb zinc ions,the OLPCs prepared by K_(2)CO_(3)activation at 800℃with higher C=O content and microporosity deliver superior capacitive performance(256 F g^(-1)at 0.1 A g^(-1))than that by KOH activation at 800℃(224 F g^(-1)at 0.1 A g^(-1)),and excellent cycling stability.This work provides a new insight into the sustainable preparation of oxygenrich porous carbon cathodes through efficient potassium activation for ZIHCs.
基金supported by the National Key R&D Program of China,Nos.2017YFA0104302(to NG and XM)and 2017YFA0104304(to BW and ZZ)
文摘Mesenchymal stromal cell transplantation is an effective and promising approach for treating various systemic and diffuse diseases.However,the biological characteristics of transplanted mesenchymal stromal cells in humans remain unclear,including cell viability,distribution,migration,and fate.Conventional cell tracing methods cannot be used in the clinic.The use of superparamagnetic iron oxide nanoparticles as contrast agents allows for the observation of transplanted cells using magnetic resonance imaging.In 2016,the National Medical Products Administration of China approved a new superparamagnetic iron oxide nanoparticle,Ruicun,for use as a contrast agent in clinical trials.In the present study,an acute hemi-transection spinal cord injury model was established in beagle dogs.The injury was then treated by transplantation of Ruicun-labeled mesenchymal stromal cells.The results indicated that Ruicunlabeled mesenchymal stromal cells repaired damaged spinal cord fibers and partially restored neurological function in animals with acute spinal cord injury.T2*-weighted imaging revealed low signal areas on both sides of the injured spinal cord.The results of quantitative susceptibility mapping with ultrashort echo time sequences indicated that Ruicun-labeled mesenchymal stromal cells persisted stably within the injured spinal cord for over 4 weeks.These findings suggest that magnetic resonance imaging has the potential to effectively track the migration of Ruicun-labeled mesenchymal stromal cells and assess their ability to repair spinal cord injury.
基金The authors would like to thank Li LI and H.Z.Xie for the technical support.This work was financially supported by the National Natural Science Foundation of China(Nos.82002303 and 81702171)the Guangdong Basic and Applied Basic Research Foundation(Nos.2022A1515011536,2021A1515220093,2021A1515220086,2019A1515111156,and 2022A1515011815)+7 种基金the Scientific Research Foundation of Peking University Shenzhen hospital(No.KYQD2021064)the Health and Medical Research Fund(No.19180712)the Shenzhen Double Chain Project for Innovation and Development Industry supported by the Bureau of Industry and Information Technology of Shenzhen(No.201806081018272960)the Shenzhen Science and Technology Innovation Committee Projects(Nos.JCYJ20190809182213535 and JSGG20180507183242702)the program from Shanghai Municipal Health Commission(No.201740165)the National Key R&D Program of China(No.2018YFC1105100)the Hong Kong Innovation Technology Fund(Nos.ITS/287/17 and ITS/405/18)the Hong Kong Research Grant Council General Research Fund(No.17214516).
文摘The healing of critical-sized bone defects(CSD)remains a challenge in orthopedic medicine.In recent years,scaffolds with sophisticated microstructures fabricated by the emerging three-dimensional(3D)printing technology have lighted up the treatment of the CSD due to the elaborate microenvironments and support they may build.Here,we established a magnesium oxide-reinforced 3D-printed biocompos-ite scaffold to investigate the effect of magnesium-enriched 3D microenvironment on CSD repairing.The composite was prepared using a biodegradable polymer matrix,polycaprolactone(PCL),and the disper-sion phase,magnesium oxide(MgO).With the appropriate surface treatment by saline coupling agent,the MgO dispersed homogeneously in the polymer matrix,leading to enhanced mechanical performance and steady release of magnesium ion(Mg^(2+))for superior cytocompatibility,higher cell viability,advanced osteogenic differentiation,and cell mineralization capabilities in comparison with the pure PCL.The in-vivo femoral implantation and critical-sized cranial bone defect studies demonstrated the importance of the 3D magnesium microenvironment,as a scaffold that released appropriate Mg^(2+) exhibited remarkably increased bone volume,enhanced angiogenesis,and almost recovered CSD after 8-week implantation.Overall,this study suggests that the magnesium-enriched 3D scaffold is a potential candidate for the treatment of CSD in a cell-free therapeutic approach.
基金financially supported by the Beijing Municipal Science & Technology Commission (No. Z171100002217048)the National Natural Science Foundation of China (No. 51705489)
文摘Diffusion bonding of refractory Nb–Si-based alloy was performed with Ni/Al and Ti/Al nanolayers under the condition of 1473 K/30 MPa/60 min.The NbSS/Nb5Si3 in situ composite with the nominal composition of Nb–22 Ti–16 Si–3 Cr–3 Al–2 Hf was used as the parent material.The joint microstructures were examined by using a scanning electron microscope equipped with an X-ray energy dispersive spectrometer.Shear test was conducted for the bonded joints at room temperature.Within the joint bonded with Ni/Al multilayer,element diffusion occurred between the base metal and the nanolayer,with the reaction products of AlNb2+Ni3 Al,NiAl and AlNi2 Ti phases.The average shear strength was 182 MPa.While using Ti/Al multilayer,the interface mainly consisted of TiAl,(Ti,Nb)Al and(Ti,Nb)2 Al phases,and the corresponding joints exhibited an increased strength of 228 MPa.In this case,the fracture mainly took place in the TiAl phase and presented a typical brittle characteristic.
基金supported by NSFC (Grant Nos. 11522328, 11473070, 11427803 and U1731241)CAS Strategic Pioneer Program on Space Science (Grant Nos. XDA15010600, XDA15052200, XDA15320103 and XDA15320301)the National Key Research and Development Program of China (2018YFA0404202)
文摘The Advanced Space-based Solar Observatory(ASO-S) mission aims to explore the two most spectacular eruptions on the Sun: solar flares and coronal mass ejections(CMEs), and their magnetism.For the study of CMEs, the payload Lyman-alpha Solar Telescope(LST) has been proposed. It includes a traditional white-light coronagraph and a Lyman-alpha coronagraph which opens a new window to CME observations. Polarization measurements taken by white-light coronagraphs are crucial for deriving fundamental physical parameters of CMEs. To make such measurements, there are two options for a Stokes polarimeter which have been applied by existing white-light coronagraphs for space missions. One uses a single or triple linear polarizer, the other involves both a half-wave plate and a linear polarizer. We find that the former option is subject to less uncertainty in the derived Stokes vector propagating from detector noise.The latter option involves two plates which are prone to internal reflections and may have a reduced transmission factor. Therefore, the former option is adopted as our Stokes polarimeter scheme for LST. Based on the parameters of the intended linear polarizer(s) colorPol provided by CODIXX and the half-wave plate 2-APW-L2-012 C by Altechna, it is further shown that the imperfect maximum transmittance of the polarizer significantly increases the variance amplification of Stokes vector by at least about 50% when compared with the ideal case. The relative errors of Stokes vector caused by the imperfection of colorPol polarizer and the uncertainty due to the polarizer assembly in the telescope are estimated to be about 5%. Among the considered parameters, we find that the dominant error comes from the uncertainty in the maximum transmittance of the polarizer.
基金funded by National Key Research, Development Program of China (No. 2017YFE0301305KYWX-002)Sichuan Science and Technology Program (No. 2021YFSY0015)
文摘Atmospheric pressure plasma jet(APPJ)was used to clean nitrogen-containing carbon films(C–N)fabricated by plasma-assisted chemical vapor deposition method employing the plasma surface interaction linear device at Sichuan University(SCU-PSI).The properties of the contaminated films on the surface of pristine and He-plasma pre-irradiated tungsten matrix,such as morphology,crystalline structure,element composition and chemical structure were characterized by scanning electron microscopy,grazing incidence x-ray diffraction and x-ray photoelectron spectroscopy.The experimental results revealed that the removal of C–N film with a thickness of tens of microns can be realized through APPJ cleaning regardless of the morphology of the substrates.Similar removal rates of 16.82 and 13.78μm min^(-1)were obtained for C–N films deposited on a smooth pristine W surface and rough fuzz-covered W surface,respectively.This is a remarkable improvement in comparison to the traditional cleaning method.However,slight surface oxidation was found after APPJ cleaning,but the degree of oxidation was acceptable with an oxidation depth increase of only 3.15 nm.Optical emission spectroscopy analysis and mass spectrometry analysis showed that C–N contamination was mainly removed through chemical reaction with reactive oxygen species during APPJ treatment using air as the working gas.These results make APPJ cleaning a potentially effective method for the rapid removal of C–N films from the wall surfaces of fusion devices.
基金supported by the National Natural Science Foundation of China(Grant Nos.:31971308,81960769,and U1903211)National S&T Major Project(Grant No.:2019ZX09301-147),Luzhou Science and Technology Plan(Grant No.:2018CDLZ10)Sichuan Science and Technology Program(Grant No.:2021YFS0081).
文摘Traditional microtubule inhibitors fail to significantly enhance+e effect of colorectal cancer;hence,new and efficient strategies are necessary.In+is study,a supramolecular nanoreactor(DOC@TA-Fe^(3+))based on tannic acid(TA),iron ion(Fe^(3+)),and docetaxel(DOC)wi+microtubule inhibition,reactive oxygen species(ROS)generation,and gluta+ione peroxidase 4(GPX4)inhibition,is prepared for ferroptosis/apoptosis treatment.After internalization by CT26 cells,+e DOC@TA-Fe^(3+)nanoreactor escapes from+e lysosomes to release payloads.+e subsequent Fe^(3+)/Fe^(2+)conversion mediated by TA reducibility can trigger+e Fenton reaction to enhance+e ROS concentration.Additionally,Fe^(3+)can consume gluta+ione to repress+e activity of GPX4 to induce ferroptosis.Meanwhile,+e released DOC controls microtubule dynamics to activate+e apoptosis pa+way.+e superior in vivo antitumor efficacy of DOC@TA-Fe^(3+)nanoreactor in terms of tumor grow+inhibition and improved survival is verified in CT26 tumor-bearing mouse model.+erefore,+e nanoreactor can act as an effective apoptosis and ferroptosis inducer for application in colorectal cancer+erapy.
基金the Special Foundation for Theoretical Physics Research Program of China(Grant No.11847065)the Natural Science Foundation of Shanxi Province,China(Grant No.201901D211115).
文摘Based on ab initio density functional theory calculations,we demonstrate that two carbon-doped boron nitride analog ofα-graphyne structures,B_(3) C_(2) N_(3)) and BC_(6) N monolayers,are two-dimensional direct wide band gap semiconductors,and there are two inequivalent valleys in the vicinities of the vertices of their hexagonal Brillouin zones.Besides,B_(3)C_(2)N_(3) and BC_(6)N monolayers exhibit relatively high carrier mobilities,and their direct band gap feature is robust against the biaxial strain.More importantly,the energetically most favorable B_(3)C_(2)N_(3) and BC_(6)N bilayers also have direct wide band gaps,and valley polarization could be achieved by optical helicity.Finally,we show that BC_(6) N monolayer might have high efficiency in photo-splitting reactions of water,and a vertical van der Waals heterostructure with a type-Ⅱenergy band alignment could be designed using B_(3)C_(2)N_(3)and BC_(6)N monolayers.All the above-mentioned characteristics make B_(3)C_(2)N_(3) and BC_(6)N monolayers,bilayers,and their heterostructures recommendable candidates for applications in valleytronic devices,metal-free photocatalysts,and photovoltaic cells.
基金supported by 2021–2022 Hunan Province Enterprise Science and Technology Commissioner Program Project under the Contract No.2021GK5046the project supported by Scientific Research Fund of Hunan Provincial Education Department under the Contract No.19C0476the project supported by Scientific Research Fund of Hunan Institute of Engineering under the Contract No.XJ1902.
文摘The formation process of aromatic hydrocarbon tar during the pyrolysis process of biomass components of cel-lulose and lignin was carried out by quantum chemical calculation based on density functional theory method B3LYP/6-31G++(d,p).5 Hydroxymethylfurfural was chosen as the model compound of cellulose and hemicel-lulose,and syringa ldehyde was chosen as the model compound of lignin.The calculation results show that the formation process of cellulose monocyclic aromatic hydrocarbon tar is the conversion process of benzene ring from furan ring,and the highest reaction energy barrier appears in the process of decarbonylation,which is 370.8 kJ/mol.The formation of lignin monocyclic aromatic hydrocarbon tar is mainly the process of side chains removal and the formation of phenol,The highest reaction energy barrier appears in the process of decarbonyla-tion,which is 374.9 kJ/mol.The reaction mechanism of phenanthrene formation from naphthalene was selected as the formation of cellulose and lignin polycydic aromatic hydrocarbon tar.The calculation results show that he total barrier of the pathway that naphthalene dehydrogenates to form naphthalene free radicals and then reacts with ethylene twice by addition action,finally occurs cydization reactions and isomerizes to produce phenan-threne is lowest,that is 38.6 kJ/mol.So it is proved that the evolution of tar is the process of deoxygenation and cyclization with the increase of the temperature from a theoretical point of view.
基金National Key Research and Development Program of China(Grant No.2017YFA0104302)the National Natural Science Innovative Research Group Project(Grant No.61821002)+1 种基金the Natural Science Foundation of Jiangsu Province(Grant No.BK20190938)the Key Projects of the National Natural Science Foundation of China(Grant No.51832001).
文摘Oral iron supplements such as ferrous iron salts are major treatment agents for iron deficiency anemia(IDA)due to the convenience of large dose administration and good patient compliance.However,the gastrointestinal adverse impact caused by Fe2+stimulus and low bioavailability severely impedes its therapeutic effects.In recent years,it has been found that nano iron⁃based nanoparticles with high surface⁃to⁃volume ratio and low iron ion leakage can alleviate the toxic effect and improve the gastrointestinal absorbance.For further clinical development,nano materials need to meet the pharmaceutical quality demand.Carboxymethyl cellulose(CMC)is a significant pharmaceutical ingredient applied in approved drug formulations,and polyglucosorbitol carboxymethylether(PSC)has been utilized in iron⁃based nanomedicine ferumoxytol synthesis,both of which can be firmly anchored on iron oxide by carboxyl chelation.In this work,iron oxide nanoparticles(NPs)modified with CMC were designed and synthesized,and the structure composition and physicochemical properties were distinctly characterized.Oral supplement effects on rat IDA were investigated and compared with other recently reported iron supplements including NPs modified with PSC.Results show that the oral nano iron supplement achieved the recovery of hemoglobin and serum iron level in only two weeks with high safety.The nano iron oxide modified with pharmaceutical excipients provides new potential approach for oral iron supplement available in clinics.
基金the National Science Foundation of China(41327802,41774152 and 41674155)in part by Youth Innovation Promotion Association of the Chinese Academy of Sciences(2017258)the Strategic Priority Program on Space Science,Chinese Academy of Sciences,Grant No.XDA15350203。
文摘New observations of auroras based on the wide-field aurora imager(WAI)onboard Fengyun-3D(FY-3D)satellite are exhibited in this paper.Validity of the WAI data is analyzed by comparing auroral boundaries derived from WAI observations with results obtained from data collected by the Special Sensor Ultraviolet Spectrographic Imager(SSUSI)aboard the Defense Meteorological Satellite Program(DMSP F18).Dynamic variations of the aurora with the solar wind,interplanetary magnetic field(IMF)parameters,and the SYM-H index are also investigated.The comparison of auroral boundaries indicates that the WAI data are morphologically valid and suitable to the study of auroral dynamics.Effective responses to solar wind parameters indicate that the WAI data can be useful to monitor and predict the Earth’s space weather.Since the configuration of aurora is a good indicator of the solar wind–magnetosphere–ionosphere(SW-M-I)coupling system,and can reflect the disturbance of the space environment,the WAI will provide important data to help us to study the physical processes in space.
基金supported by the State Key Development Program for Basic Research of China (No. 2014CB932204)the Special Fund for Agro-Scientific Research in the Public Interest of China (No. 200903054)
文摘In China, although improvements to the pesticide registration process have been made in la thirty years, no occupational exposure data are required to obtain a commercial license for pesticide product. Consequently, notably little research has been conducted to establish a exposure assessment procedure in China. The present study monitored the potential derm operator exposure from knapsack electric sprayer wheat field application of imidacloprid Liaocheng City, Shandong Province and in Xinxiang City, Henan Province, China, usin whole-body dosimetry. The potential inhalation exposure was determined using a person air pump and XAD-2 sample tubes. The analytical method was developed and validate including such performance parameters as limits of detection and quantification, linear rang recovery and precision. The total potential dermal and inhalation exposures were 14.20, 16.815.39 and 20.78 mL/hr, respectively, for the four operators in Liaocheng and Xinxian corresponding to 0.02% to 0.03% of the applied volume of spray solution. In all trials, the low part（thigh, lower leg） of the body was the most contaminated, accounting for approximate76% to 88% of the total exposure. The inhalation exposure was less than 1% of the tot exposure. Such factors as the application pattern, crop type, spray equipment, operat experience and climatic conditions have been used to explain the exposure distribution ov the different parts of the body. As indicated by the calculated Margin of Exposure, the typic wheat treatment scenarios when a backpack sprayer was used are considered to be safe terms of imidacloprid exposure.
文摘Objective： To evaluate the effect of transplanting bone marrow-derived mesenchymal stem cells （BM-MSCs） or adenovirus5- hepatocyte growth factor（Ad5-HGF） via non-infarct-related artery injection in swine myocardial infarction models. Methods：BMMSCs were obtained from swine bone marrow and expanded in vitro to a purity of 〉50%. A myocardial infarction（MI） was created by ligating the distal left anterior descending artery in swine. Either BM-MSCs （5 × 10^6/ml） or Ad5-HGF （4 × 10^9 pfu） were transfused via the right coronary artery （non-infarcted artery） four weeks after MI. Gate-controled cardiac perfusion imaging was performed at the end of four and seven weeks after LAD ligation, to evaluate heart function and cardiac perfusion. Morphologic and histologic characteristics of the hearts were also studied. Results： （1）The gate-controlled cardiac perfusion imaging showed that the improvement in LVEF was greater in both treatment groups than in control group at the 4^th weeks. （2）In both treatment groups, capillary density was significantly higher than that of control group（P 〈 0.05）. Conclusion ：BM-MSCs or Ad5-HGF transplantation via non-infarcted artery administration can stimulate angiogenesis and improve heart function, but there was no difference in therapeutic efficacy between BM-MSCs and Ad5-HGF.
基金The first author and the third author were supported by the National Natural Science Foundation of China (11761030)the Cultivation Project for High-Level Scientific Research Achievements of Hubei Minzu University (PY20002)The second author was supported by the China Postdoctoral Science Foundation (2021M690773)。
文摘In the present paper, we consider the problem {-△u=u^(β_(1))|■u|^(β_(2)),in Ω,u=0,on ■Ω,u>0,in Ω,(0.1) where β_(1), β_(2) > 0 and β_(1) + β_(2) < 1, and Ω is a convex domain in R~n. The existence, uniqueness,regularity and (2-β_(2))/(1-β_(1)-β_(2))-concavity of the positive solutions of the problem(0.1) are proven.
基金supported by the National Key R&D Program of China(2021YFA0718600)the National Natural Science Foundations of China(NSFC,Grant Nos.41931073,41774195)+2 种基金Ten-thousand Talents Program of JingSong Wang,and the Specialized Research Fund for State Key Laboratoriessupported by the Strategic Priority Research Program of the Chinese Academy of Sciences,Grant No.XDA 15018400supported by the China Postdoctoral Science Foundation(2021M700246)。
文摘Extreme ultraviolet(EUV)observations are widely used in solar activity research and space weather forecasting since they can observe both the solar eruptions and the source regions of the solar wind.Flat field processing is indispensable to remove the instrumental non-uniformity of a solar EUV imager in producing high-quality scientific data from original observed data.FengYun-3E(FY-3E)is a meteorological satellite operated in a Sunsynchronous orbit,and the routine EUV imaging data from the Solar X-ray and Extreme Ultraviolet Imager(X-EUVI)onboard FY-3E has the characteristic of concentric rotation.Taking advantage of the concentric rotation,we propose a post-hoc flat field measurement method for its EUV 195A channel in this paper.This method removes the small-scale and time-varying component of coronal activities by taking the median value for each pixel along the time axis of a concentric rotation data cube,and then derives the large-scale and invariable component of the quiet coronal radiation,and finally generates a flat field image.The flat field can be generated with cadences from hundreds of minutes(one orbit)to several days.Higher flat field accuracy can be achieved by employing more data.Further analysis shows that our method is able to measure the instrumental spot-like nonuniformity possibly caused by contamination on the detector,which mostly disappears after the in-orbit selfcleaning process.It can also measure the quasi-periodic grid-like non-uniformity,possibly from the obscuration of the support mesh on the rear filter.After flat field correction,these instrumental non-uniformities from the original data are effectively removed.Moreover,the X-EUVI 195A data after dark and flat field corrections are consistent with the 193A imaging data from the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory,verifying the suitability of the method.The post-hoc method does not occupy observation time,which is advantageous for space weather operations.Our method is not only suitable for FY-3E/X-EUVI but also a candidate method for the flat field measurement of future solar EUV telescopes.
文摘This paper interrogates the impact of policy events on the efficiency of carbon market in China.The analysis covers five piloting emission trading schemes(Beijing, Shanghai, Guangdong,Shenzhen and Hubei), particularly focusing on Guangdong pilot for its weak form efficiency and the richness of policy events. Twenty-five policy events between 2014 and 2016 are categorized into seven groups. The efficiency test indicates that only Guangdong ETS has reached weak form efficiency. After exploring the policy events occurred in Guangdong ETS, it finds that although a clear long-term climate policy has been set up over the country, China's carbon market still has a conservative risk appetite and its governing institutions still needs further development. The policy makers need to be aware of and avoid the negative impacts of policy events to the market evolvement, by introducing effective consultancy process with the stakeholders and nurturing market expectations in the long run. We also find that events like allowance auctions have considerably less impacts than previously expected and argue that auction approach should be considered a preferable option over a free allocation system in the future policy design.
文摘Carbonate electrolytes are one of the most desirable electrolytes for high-energy lithium-sulfur batteries(LSBs)because of their successful implementation in commercial Li-ion batteries.The low-polysulfide-solubility feature of some carbonate solvents also makes them very promising for overcoming the shuttle effects of LSBs.However,regular sulfur electrodes experience undesired electrochemical mechanisms in carbonate electrolytes due to side reactions.In this study,we report a catalytic redox mechanism of sulfur in propylene carbonate(PC)electrolyte based on a compari-son study.The catalytic mechanism is characterized by the interactions between polysulfides and dual N/O functional groups on the host carbon,which largely prevents side reactions between polysulfides and the carbonate electrolyte.Such a mechanism coupled with the low-polysulfide-solubility feature leads to stable cycling of LSBs in PC electrolyte.Favorable dual N/O functional groups are identified via a density functional theory study.This work provides an alternative route for enabling LSBs in carbonate electrolytes.
基金by National Natural Science Foundation of China(No.11875198)Young Scientists Fund of National Natural Science Foundation of China(No.11905151)+1 种基金Fundamental Research Funds for the Central Universities of China(No.2019SCU12072)the China Postdoctoral Science Foundation(No.2019M663487).
文摘The net erosion yield of CX-2002U carbon fiber composites under high-flux low-temperature hydrogen plasma is investigated using a linear plasma device.It is found that the net erosion yield decreases rapidly first,and then tends to saturate with the increase of hydrogen–plasma flux.When the temperature of the sample eroded by hydrogen plasma is above 300°C,the hybridization of electrons outside the carbon atom would change.Then the carbon atoms combine with hydrogen atoms to form massive spherical nanoparticles of hydrocarbon compounds and deposit on the surface at the flux condition of 1.77×10^(22) m^(−2)·s^(−1).Under the irradiation of hydrogen plasma loaded with negative bias,the surface morphology of the matrix carbon is changed dramatically.Moreover,the energy dependence of mass loss does not increase in proportion to the increase of hydrogen–plasma energy,but reaches a peak around 20 V negative bias voltage.Based on the analysis of different samples,it can be concluded that the enhancement of energy could make a contribution to chemical erosion and enlarge the size of pores existing on the surface.
基金Project supported by the Sichuan Provincial Science and Technology Program,China(Grant Nos.2021YFSY0015and 2021YJ0510)the China Postdoctoral Science Foundation(Grant No.2019M663487)the National Natural Science Foundation of China(Grant No.11905151)。
文摘Steady high-flux helium(He)plasma with energy ranging from 50 eV to 90 eV is used to fabricate a fiber-form nanostructure called fuzz on a polycrystalline molybdenum(Mo)surface.Enhanced hydrogen(H)pulsed plasma in a wide power density range of 12 MW/m^(2)-35 MW/m^(2)is subsequently used to bombard the fuzzy Mo,thereby simulating the damage of edge localized mode(ELM)to fuzz.The comparisons of surface morphologies,crystalline structures,and optical reflectivity between the original Mo and the Mo treated with various He^(+)energy and transient power densities are performed.With the increase of He ion energy,the Mo nano-fuzz evolved density is enlarged due to the decrease of filament diameter and optical reflectivity.The fuzz-enhanced He release should be the consequence of crystalline growth and the lattice shrinkage inside the Mo-irradiated layers(^(2)00 nm).The fuzz induced by lower energy experiences more severe melting damage and dust release under the condition of the identical transient H plasma-bombardment.The H and He are less likely to be trapped due to aggravated melting evidenced by the enhanced crystalline size and distinct lattice shrinkage.As the transient power density rises,the thermal effect is enhanced,thereby causing the fuzz melting loss to aggravate and finally to completely disappear when the power density exceeds 21 MW/m^(2).Irreversible grain expansion results in huge tensile stress,leading to the observable brittle cracking.The effects of transient thermal load and He ion energy play a crucial role in etching Mo fuzz during ELM transient events.
