A novel extraction method of baicalin from radix scutellariae was explored in this study. Liquid-liquid continuous biphasic extraction was a new method, and showed the advantage of high extracting contents of total fl...A novel extraction method of baicalin from radix scutellariae was explored in this study. Liquid-liquid continuous biphasic extraction was a new method, and showed the advantage of high extracting contents of total flavone compared with one of the traditional methods. The novel extraction method which is easy to operate and has good reproducibility was much more effective than the traditional one.展开更多
A rapid and heterogeneous Pd/C-catalyzed atom-efficient phenylation of aryl bromides by sodium tetraphenylborate takes place under focused microwave irradiation in water. The palladium catalyst can be easily recovered...A rapid and heterogeneous Pd/C-catalyzed atom-efficient phenylation of aryl bromides by sodium tetraphenylborate takes place under focused microwave irradiation in water. The palladium catalyst can be easily recovered and reused.展开更多
The tremendous development of Synthetic Aperture Radar(SAR)missions in recent years facilitates the study of smaller amplitude ground deformation over greater spatial scales using longer time series.However,this poses...The tremendous development of Synthetic Aperture Radar(SAR)missions in recent years facilitates the study of smaller amplitude ground deformation over greater spatial scales using longer time series.However,this poses greater challenges for correcting atmospheric effects due to the wider coverage of SAR imagery than ever.Previous attempts have used observations from Global Positioning System(GPS)and Numerical Weather Models(NWMs)to separate atmospheric delays,but they are limited by(1)The availability(and distribution)of GPS stations;(2)The low spatial resolution of NWM;And(3)The difficulties in quantifying their performance.To overcome these limitations,we have developed the Generic Atmospheric Correction Online Service for InSAR(GACOS)which utilizes the high-resolution European Centre for Medium-Range Weather Forecasts(ECMWF)products using an Iterative Tropospheric Decomposition(ITD)model.This enables the reduction of the coupling effects of the troposphere turbulence and stratification and hence achieves equivalent performances over flat and mountainous terrains.GACOS comprises a range of notable features:(1)Global coverage;(2)All-weather,all-time usability;(3)Available with a maximum of two-day latency;And(4)Indicators available to assess the model’s performance and feasibility.In this paper,we demonstrate some successful applications of the GACOS online service to a variety of geophysical studies.展开更多
We synthesized NaY(MoO4)2:Eu3+phosphors of different doping concentrations by a molten salt method.This facile way possesses advantages such as simple process,lower calcination temperature(350℃)and small particle siz...We synthesized NaY(MoO4)2:Eu3+phosphors of different doping concentrations by a molten salt method.This facile way possesses advantages such as simple process,lower calcination temperature(350℃)and small particle size(70 nm).The crystal system is tetragonal phase and crystal lattice is body centered.The photo luminescence measurements including emission spectra,excitation spectra and fluorescence decay curves were carried out,elucidating that NaY(MoO4)2:Eu3+can be effectively excited by near UV and blue light.Moreover,it can be concluded that Eu3+energy transfer type is exchange interaction.Huang-Rhys factor and the critical energy transfer distance(Rc)were calculated to be 0.043 and 0.995 nm,respectively.Auzel’s model was used to obtain the intrinsic radiative transition lifetime of5 D0 level(τ0=0.923 ms).Furthermore,a calculation method was used to calculate refractive index n of nontransparent NaY(MoO4)2:1 mol%Eu3+phosphor,and n was obtained to be 1.86.展开更多
Our previous study used regional homogeneity analysis and found that activity in some brain areas of patients with ischemic stroke changed significantly. In the current study, we examined structural changes in these b...Our previous study used regional homogeneity analysis and found that activity in some brain areas of patients with ischemic stroke changed significantly. In the current study, we examined structural changes in these brain regions by taking structural magnetic resonance imaging scans of 11 ischemic stroke patients and 15 healthy participants, and analyzing the data using voxel-based morphometry. Compared with healthy participants, patients exhibited higher gray matter density in the left inferior occipital gyrus and right anterior white matter tract. In contrast, gray matter density in the right cerebellum, left precentral gyrus, right middle frontal gyrus, and left middle temporal gyrus was less in ischemic stroke patients. The changes of gray matter density in the middle frontal gyrus were negatively associated with the clin- ical rating scales of the Fugl-Meyer Motor Assessment （r = -0.609, P = 0.047） and the left middle temporal gyrus was negatively correlated with the clinical rating scales of the nervous functional deficiency scale （r = -0.737, P = 0.010）. Our findings call objectively identify the functional abnormality in some brain regions of ischemic stroke patients.展开更多
Long noncoding RNAs(lnc RNAs) are RNA molecules comprising more than 200 nucleotides, which are not translated into proteins. Many studies have shown that lnc RNAs are involved in regulating a variety of biological pr...Long noncoding RNAs(lnc RNAs) are RNA molecules comprising more than 200 nucleotides, which are not translated into proteins. Many studies have shown that lnc RNAs are involved in regulating a variety of biological processes, including immune, cancer, stress, development and differentiation at the transcriptional, epigenetic or post-transcriptional levels. Here, we review the role of lnc RNAs in the process of neurodevelopment, neural differentiation, synaptic function, and pathogenesis of Parkinson’s disease(PD). These pathomechanisms include protein misfolding and aggregation, disordered protein degradation, mitochondrial dysfunction, oxidative stress, autophagy, apoptosis, and neuroinflammation. This information will provide the basis of lnc RNA-based disease diagnosis and drug treatment for PD.展开更多
Objective To compare the similarities and differences of early CT manifestations of three types of viral pneumonia induced by SARS-CoV-2(COVID-19),SARS-CoV(SARS)and MERS-CoV(MERS)using a systemic review.Methods Electr...Objective To compare the similarities and differences of early CT manifestations of three types of viral pneumonia induced by SARS-CoV-2(COVID-19),SARS-CoV(SARS)and MERS-CoV(MERS)using a systemic review.Methods Electronic database were searched to identify all original articles and case reports presenting chest CT features for adult patients with COVID-19,SARS and MERS pneumonia respectively.Quality of literature and completeness of presented data were evaluated by consensus reached by three radiologists.Vote-counting method was employed to include cases of each group.Data of patients’manifestations in early chest CT including lesion patterns,distribution of lesions and specific imaging signs for the three groups were extracted and recorded.Data were compared and analyzed using SPSS 22.0.Results A total of 24 studies were included,composing of 10 studies of COVID-19,5 studies of MERS and 9 studies of SARS.The included CT exams were 147,40,and 122 respectively.For the early CT features of the 3 pneumonias,the basic lesion pattern with respect to"mixed ground glass opacity(GGO)and consolidation,GGO mainly,or consolidation mainly"was similar among the 3 groups(χ^2=7.966,P>0.05).There were no significant differences on the lesion distribution(χ^2=13.053,P>0.05)and predominate involvement of the subpleural area of bilateral lower lobes(χ^2=4.809,P>0.05)among the 3 groups.The lesions appeared more focal in COVID-19 pneumonia at early phase(χ^2=23.509,P<0.05).The proportions of crazy-paving pattern(χ^2=23.037,P<0.001),organizing pneumonia pattern(P<0.05)and pleural effusions(P<0.001)in COVID-19 pneumonia were significantly lower than the other two.Although rarely shown in the early CT findings of all three viral pneumonias,the fibrotic changes were more frequent in SARS than COVID-19 and MERS(χ^2=6.275,P<0.05).For other imaging signs,only the MERS pneumonia demonstrated tree-in-buds,cavitation,and its incidence rate of interlobular or intralobular septal thickening presented significantly increased as compared to the other two pneumonia(χ^2=22.412,P<0.05).No pneumothorax,pneumomediastinum and lymphadenopathy was present for each group.Conclusions Imaging findings on early stage of these three coronavirus pneumonias showed similar basic lesion patterns,including GGO and consolidation,bilateral distribution,and predominant involvement of the subpleural area and the lower lobes.Early signs of COVID-19 pneumonia showed less severity of inflammation.Early fibrotic changes appeared in SARS only.MERS had more severe inflammatory changes including cavitation and pleural effusion.The differences may indicate the specific pathophysiological processes for each coronavirus pneumonia.展开更多
Alzheimer's disease(AD)is a neurodegenerative disorder.The pathology of AD is characterized by extracellular amyloid beta(Aβ)plaques,neurofibrillary tangles com-posed of hyperphosphorylated tau,neuronal death,syn...Alzheimer's disease(AD)is a neurodegenerative disorder.The pathology of AD is characterized by extracellular amyloid beta(Aβ)plaques,neurofibrillary tangles com-posed of hyperphosphorylated tau,neuronal death,synapse loss,and brain atrophy.Many therapies have been tested to improve or at least effectively modify the course of AD.Meaningful data indicate that the transplantation of stem cells can alleviate neuropathology and significantly ameliorate cognitive deficits in animal models with Alzheimer's disease.Transplanted stem cells have shown their inherent advantages in improving cognitive impairment and memory dysfunction,although certain weak-nesses or limitations need to be overcome.This review recapitulates rodent models for AD,the therapeutic efficacy of stem cells,influencing factors,and the underlying mechanisms behind these changes.Stem cell therapy provides perspective and chal-lenges for its clinical application in the future.展开更多
DNA double-strand break(DSB) is the most severe form of DNA damage,which is repaired mainly through high-fidelity homologous recombination(HR) or error-prone non-homologous end joining(NHEJ).Defects in the DNA damage ...DNA double-strand break(DSB) is the most severe form of DNA damage,which is repaired mainly through high-fidelity homologous recombination(HR) or error-prone non-homologous end joining(NHEJ).Defects in the DNA damage response lead to genomic instability and ultimately predispose organs to cancer.Nicotinamide phosphoribosyltransferase(Nampt),which is involved in nicotinamide adenine dinucleotide metabolism,is overexpressed in a variety of tumors.In this report,we found that Nampt physically associated with CtIP and DNA-PKcs/Ku80,which are key factors in HR and NHEJ,respectively.Depletion of Nampt by small interfering RNA(siRNA) led to defective NHEJ-mediated DSB repair and enhanced HR-mediated repair.Furthermore,the inhibition of Nampt expression promoted proliferation of cancer cells and normal human fibroblasts and decreased β-galactosidase staining,indicating a delay in the onset of cellular senescence in normal human fibroblasts.Taken together,our results suggest that Nampt is a suppressor of HR-mediated DSB repair and an enhancer of NHEJ-mediated DSB repair,contributing to the acceleration of cellular senescence.展开更多
The rapid development of additive manufacturing technology has offered a new avenue for designing and fabricating high wave-absorbing meta structures.In this study,the mechanical properties and broadband absorption pe...The rapid development of additive manufacturing technology has offered a new avenue for designing and fabricating high wave-absorbing meta structures.In this study,the mechanical properties and broadband absorption performance of Poly-Ether-Ether-Ketone(PEEK)–based electromagnetic wave–absorbing composite materials was investigated.The high-performance polymer PEEK was used as the matrix,and the materials with electromagnetic wave loss,such as reduced graphene oxide,Carbonyl Iron(CI),and Flake CI(FCI),were used as absorbers.Based on the theory of impedance matching,a wave-absorbing structure with a gradual impedance gradient was designed and printed.The test results showed that at the 2.0–18.0 GHz frequency band,the coverage rate of the effective absorption bandwidth was up to 72.0%,the average optimal reflectivity was–18.09 dB,and the wide-angle absorption range was 0°–30°.The advantages of additive manufacturing technology in designing and fabricating wave-absorbing structures are presented,demonstrating that the technology is an effective method for creating broadband absorbing structures.展开更多
Unmanned aerial vehicles(UAVs)have attracted growing research interests in recent years,which can be used as cost-effective aerial platforms to transmit collected data packets to ground access points(APs).Thus,it is c...Unmanned aerial vehicles(UAVs)have attracted growing research interests in recent years,which can be used as cost-effective aerial platforms to transmit collected data packets to ground access points(APs).Thus,it is crucial to investigate robust airto-ground(A2G)wireless links for high-speed UAVs.However,the A2G wireless link is unstable as it suffers from large path-loss and severe Doppler effect due to the high mobility of UAVs.In order to meet these challenges,we propose an orthogonal time frequency space(OTFS)-based UAV communication system to relief the Doppler effect.Besides,considering that the energy of UAV is limited,we optimize the trajectory planning of UAV to minimize the energy consumption under the constraints of bit error rate(BER)and transmission rate,where the Doppler compensation is taken into account.Simulation results show that the performance of OTFS-based UAV system is superior to orthogonal frequency division multiplexing(OFDM)-based UAV systems,which can accomplish transmission tasks over shorter distances with lower energy consumption.展开更多
文摘A novel extraction method of baicalin from radix scutellariae was explored in this study. Liquid-liquid continuous biphasic extraction was a new method, and showed the advantage of high extracting contents of total flavone compared with one of the traditional methods. The novel extraction method which is easy to operate and has good reproducibility was much more effective than the traditional one.
基金supported by the National Natural Science Foundation of China(No.20572086)the Gansu Natural Science Foundation of China(No.3ZS061-A25-059)the Education Department Foundation of Gansu Province (No.0511-01).
文摘A rapid and heterogeneous Pd/C-catalyzed atom-efficient phenylation of aryl bromides by sodium tetraphenylborate takes place under focused microwave irradiation in water. The palladium catalyst can be easily recovered and reused.
基金National Natural Science Foundation of China(No.41941019)Fundamental Research Funds for the Central Universities(Nos.300102260301/087,300102260404/087)。
文摘The tremendous development of Synthetic Aperture Radar(SAR)missions in recent years facilitates the study of smaller amplitude ground deformation over greater spatial scales using longer time series.However,this poses greater challenges for correcting atmospheric effects due to the wider coverage of SAR imagery than ever.Previous attempts have used observations from Global Positioning System(GPS)and Numerical Weather Models(NWMs)to separate atmospheric delays,but they are limited by(1)The availability(and distribution)of GPS stations;(2)The low spatial resolution of NWM;And(3)The difficulties in quantifying their performance.To overcome these limitations,we have developed the Generic Atmospheric Correction Online Service for InSAR(GACOS)which utilizes the high-resolution European Centre for Medium-Range Weather Forecasts(ECMWF)products using an Iterative Tropospheric Decomposition(ITD)model.This enables the reduction of the coupling effects of the troposphere turbulence and stratification and hence achieves equivalent performances over flat and mountainous terrains.GACOS comprises a range of notable features:(1)Global coverage;(2)All-weather,all-time usability;(3)Available with a maximum of two-day latency;And(4)Indicators available to assess the model’s performance and feasibility.In this paper,we demonstrate some successful applications of the GACOS online service to a variety of geophysical studies.
基金Project supported by the National Natural Science Foundation of China(51002041)
文摘We synthesized NaY(MoO4)2:Eu3+phosphors of different doping concentrations by a molten salt method.This facile way possesses advantages such as simple process,lower calcination temperature(350℃)and small particle size(70 nm).The crystal system is tetragonal phase and crystal lattice is body centered.The photo luminescence measurements including emission spectra,excitation spectra and fluorescence decay curves were carried out,elucidating that NaY(MoO4)2:Eu3+can be effectively excited by near UV and blue light.Moreover,it can be concluded that Eu3+energy transfer type is exchange interaction.Huang-Rhys factor and the critical energy transfer distance(Rc)were calculated to be 0.043 and 0.995 nm,respectively.Auzel’s model was used to obtain the intrinsic radiative transition lifetime of5 D0 level(τ0=0.923 ms).Furthermore,a calculation method was used to calculate refractive index n of nontransparent NaY(MoO4)2:1 mol%Eu3+phosphor,and n was obtained to be 1.86.
基金financially supported by the National Program on Key Basic Research Project of China(973 Program)No.2012CB518501the National Natural Science Foundation of China,No.81072864
文摘Our previous study used regional homogeneity analysis and found that activity in some brain areas of patients with ischemic stroke changed significantly. In the current study, we examined structural changes in these brain regions by taking structural magnetic resonance imaging scans of 11 ischemic stroke patients and 15 healthy participants, and analyzing the data using voxel-based morphometry. Compared with healthy participants, patients exhibited higher gray matter density in the left inferior occipital gyrus and right anterior white matter tract. In contrast, gray matter density in the right cerebellum, left precentral gyrus, right middle frontal gyrus, and left middle temporal gyrus was less in ischemic stroke patients. The changes of gray matter density in the middle frontal gyrus were negatively associated with the clin- ical rating scales of the Fugl-Meyer Motor Assessment （r = -0.609, P = 0.047） and the left middle temporal gyrus was negatively correlated with the clinical rating scales of the nervous functional deficiency scale （r = -0.737, P = 0.010）. Our findings call objectively identify the functional abnormality in some brain regions of ischemic stroke patients.
基金CAMS Innovation Fund for Medical Sciences,Grant/Award Number:2017-I2M-2-005 and 2016-I2M-2-006Beijing Natural Science Foundation,Grant/Award Number:5171001
文摘Long noncoding RNAs(lnc RNAs) are RNA molecules comprising more than 200 nucleotides, which are not translated into proteins. Many studies have shown that lnc RNAs are involved in regulating a variety of biological processes, including immune, cancer, stress, development and differentiation at the transcriptional, epigenetic or post-transcriptional levels. Here, we review the role of lnc RNAs in the process of neurodevelopment, neural differentiation, synaptic function, and pathogenesis of Parkinson’s disease(PD). These pathomechanisms include protein misfolding and aggregation, disordered protein degradation, mitochondrial dysfunction, oxidative stress, autophagy, apoptosis, and neuroinflammation. This information will provide the basis of lnc RNA-based disease diagnosis and drug treatment for PD.
文摘Objective To compare the similarities and differences of early CT manifestations of three types of viral pneumonia induced by SARS-CoV-2(COVID-19),SARS-CoV(SARS)and MERS-CoV(MERS)using a systemic review.Methods Electronic database were searched to identify all original articles and case reports presenting chest CT features for adult patients with COVID-19,SARS and MERS pneumonia respectively.Quality of literature and completeness of presented data were evaluated by consensus reached by three radiologists.Vote-counting method was employed to include cases of each group.Data of patients’manifestations in early chest CT including lesion patterns,distribution of lesions and specific imaging signs for the three groups were extracted and recorded.Data were compared and analyzed using SPSS 22.0.Results A total of 24 studies were included,composing of 10 studies of COVID-19,5 studies of MERS and 9 studies of SARS.The included CT exams were 147,40,and 122 respectively.For the early CT features of the 3 pneumonias,the basic lesion pattern with respect to"mixed ground glass opacity(GGO)and consolidation,GGO mainly,or consolidation mainly"was similar among the 3 groups(χ^2=7.966,P>0.05).There were no significant differences on the lesion distribution(χ^2=13.053,P>0.05)and predominate involvement of the subpleural area of bilateral lower lobes(χ^2=4.809,P>0.05)among the 3 groups.The lesions appeared more focal in COVID-19 pneumonia at early phase(χ^2=23.509,P<0.05).The proportions of crazy-paving pattern(χ^2=23.037,P<0.001),organizing pneumonia pattern(P<0.05)and pleural effusions(P<0.001)in COVID-19 pneumonia were significantly lower than the other two.Although rarely shown in the early CT findings of all three viral pneumonias,the fibrotic changes were more frequent in SARS than COVID-19 and MERS(χ^2=6.275,P<0.05).For other imaging signs,only the MERS pneumonia demonstrated tree-in-buds,cavitation,and its incidence rate of interlobular or intralobular septal thickening presented significantly increased as compared to the other two pneumonia(χ^2=22.412,P<0.05).No pneumothorax,pneumomediastinum and lymphadenopathy was present for each group.Conclusions Imaging findings on early stage of these three coronavirus pneumonias showed similar basic lesion patterns,including GGO and consolidation,bilateral distribution,and predominant involvement of the subpleural area and the lower lobes.Early signs of COVID-19 pneumonia showed less severity of inflammation.Early fibrotic changes appeared in SARS only.MERS had more severe inflammatory changes including cavitation and pleural effusion.The differences may indicate the specific pathophysiological processes for each coronavirus pneumonia.
基金National Natural Science Foundation of China Grant(81941012)CAMS initiative for Innovative Medicine of China(2021-I2 M-1-034)National Key Research and Development Project(2017YFA0105200).
文摘Alzheimer's disease(AD)is a neurodegenerative disorder.The pathology of AD is characterized by extracellular amyloid beta(Aβ)plaques,neurofibrillary tangles com-posed of hyperphosphorylated tau,neuronal death,synapse loss,and brain atrophy.Many therapies have been tested to improve or at least effectively modify the course of AD.Meaningful data indicate that the transplantation of stem cells can alleviate neuropathology and significantly ameliorate cognitive deficits in animal models with Alzheimer's disease.Transplanted stem cells have shown their inherent advantages in improving cognitive impairment and memory dysfunction,although certain weak-nesses or limitations need to be overcome.This review recapitulates rodent models for AD,the therapeutic efficacy of stem cells,influencing factors,and the underlying mechanisms behind these changes.Stem cell therapy provides perspective and chal-lenges for its clinical application in the future.
基金was supported by the National Natural Science Foundation of China (No.31130017, 31071190, and 30711120570)the 973 project 2010CB911904+1 种基金Funding Project for Academic Human Resources Development in Institutions of Higher Learning Under the Jurisdiction of Beijing Municipality (No. PHR20110508) to XXthe 973 project 2012CB911203 to YSC
文摘DNA double-strand break(DSB) is the most severe form of DNA damage,which is repaired mainly through high-fidelity homologous recombination(HR) or error-prone non-homologous end joining(NHEJ).Defects in the DNA damage response lead to genomic instability and ultimately predispose organs to cancer.Nicotinamide phosphoribosyltransferase(Nampt),which is involved in nicotinamide adenine dinucleotide metabolism,is overexpressed in a variety of tumors.In this report,we found that Nampt physically associated with CtIP and DNA-PKcs/Ku80,which are key factors in HR and NHEJ,respectively.Depletion of Nampt by small interfering RNA(siRNA) led to defective NHEJ-mediated DSB repair and enhanced HR-mediated repair.Furthermore,the inhibition of Nampt expression promoted proliferation of cancer cells and normal human fibroblasts and decreased β-galactosidase staining,indicating a delay in the onset of cellular senescence in normal human fibroblasts.Taken together,our results suggest that Nampt is a suppressor of HR-mediated DSB repair and an enhancer of NHEJ-mediated DSB repair,contributing to the acceleration of cellular senescence.
基金the National Natural Science Foundation of China(No.12272298).
文摘The rapid development of additive manufacturing technology has offered a new avenue for designing and fabricating high wave-absorbing meta structures.In this study,the mechanical properties and broadband absorption performance of Poly-Ether-Ether-Ketone(PEEK)–based electromagnetic wave–absorbing composite materials was investigated.The high-performance polymer PEEK was used as the matrix,and the materials with electromagnetic wave loss,such as reduced graphene oxide,Carbonyl Iron(CI),and Flake CI(FCI),were used as absorbers.Based on the theory of impedance matching,a wave-absorbing structure with a gradual impedance gradient was designed and printed.The test results showed that at the 2.0–18.0 GHz frequency band,the coverage rate of the effective absorption bandwidth was up to 72.0%,the average optimal reflectivity was–18.09 dB,and the wide-angle absorption range was 0°–30°.The advantages of additive manufacturing technology in designing and fabricating wave-absorbing structures are presented,demonstrating that the technology is an effective method for creating broadband absorbing structures.
基金supported by the National Key Research and Development Program of China(Grant 2020YFB1804800)the National Natural Science Foundation of China(Grant U22B2008 and Grant 61922010)the Beijing Natural Science Foundation(Grant JQ20019)。
文摘Unmanned aerial vehicles(UAVs)have attracted growing research interests in recent years,which can be used as cost-effective aerial platforms to transmit collected data packets to ground access points(APs).Thus,it is crucial to investigate robust airto-ground(A2G)wireless links for high-speed UAVs.However,the A2G wireless link is unstable as it suffers from large path-loss and severe Doppler effect due to the high mobility of UAVs.In order to meet these challenges,we propose an orthogonal time frequency space(OTFS)-based UAV communication system to relief the Doppler effect.Besides,considering that the energy of UAV is limited,we optimize the trajectory planning of UAV to minimize the energy consumption under the constraints of bit error rate(BER)and transmission rate,where the Doppler compensation is taken into account.Simulation results show that the performance of OTFS-based UAV system is superior to orthogonal frequency division multiplexing(OFDM)-based UAV systems,which can accomplish transmission tasks over shorter distances with lower energy consumption.
