As the channel for grain boundary diffusion(GBD)in Nd–Fe–B magnets,grain boundary(GB)phases have a very important effect on GBD.As doping elements that are commonly used to regulate the GB phases in Nd–Fe–B sinter...As the channel for grain boundary diffusion(GBD)in Nd–Fe–B magnets,grain boundary(GB)phases have a very important effect on GBD.As doping elements that are commonly used to regulate the GB phases in Nd–Fe–B sintered magnets,the influences of Ga and Zr on GBD were investigated in this work.The results show that the Zr-doped magnet has the highest coercivity increment(7.97 kOe)by GBD,which is almost twice that of the Ga-doped magnet(4.32 kOe)and the magnet without Ga and Zr(3.24 kOe).Microstructure analysis shows that ZrB_(2)formed in the Zr-doped magnet plays a key role in increasing the diffusion depth.A continuous diffusion channel in the magnet can form because of the presence of ZrB_(2).ZrB_(2)can also increase the defect concentration in GB phases,which can facilitate GBD.Although Ga can also improve the diffusion depth,its effect is not very obvious.The micromagnetic simulation based on the experimental results also proves that the distribution of Tb in the Zr-doped magnet after GBD is beneficial to coercivity.This study reveals that the doping elements Ga and Zr in Nd–Fe–B play an important role in GBD,and could provide a new perspective for researchers to improve the effects of GBD.展开更多
Diagnosis of fluids is extremely significant at high temperatures and high pressures.As an advanced imaging technique,high-energy proton radiography has great potential for application to the diagnosis of high-density...Diagnosis of fluids is extremely significant at high temperatures and high pressures.As an advanced imaging technique,high-energy proton radiography has great potential for application to the diagnosis of high-density fluids.In high-energy proton radiography,an angular collimator can control the proton flux and thus enable material diagnosis and reconstruction of density.In this paper,we propose a multimaterial diagnostic method using angular collimators.The method is verified by reconstructing the density distribution from the proton flux obtained via theoretical calculations and numerical simulations.We simulate a 20 GeV proton imaging system using the Geant4 software toolkit and obtain the characteristic parameters of single-material objects.We design several concentric spherical objects to verify the method.We discuss its application to detonation tests.The results show that this method can determine the material and boundary information about each component of a multi-material object.Thus,it can be used to diagnose a mixed material and reconstruct densities in a detonation.展开更多
Recent developments in brain magnetic resonance imaging using advanced Susceptibility Weighted Imaging (SWI) have significantly increased the detection and prevalence of Cerebral Microbleeds (CMBs). Here, we aimed to ...Recent developments in brain magnetic resonance imaging using advanced Susceptibility Weighted Imaging (SWI) have significantly increased the detection and prevalence of Cerebral Microbleeds (CMBs). Here, we aimed to explore the association between Pulse Pressure (PP) and CMBs. Having been implicated in various arteriopathies, we hypothesized that elevated PP could also be a risk for CMBs. A retrospective case-control study was conducted from August 2021 to September 2022 at Zhongnan Hospital of Wuhan University China. Extracted data were analyzed in SPSS. Chi-square test, binary logistic regression, and Spearman’s correlation analysis were conducted.104 patients were analyzed. Univariate analysis showed no significant association between PP and CMBs, OR 1.65 (95% CI: 0.737 - 3.694;p > 0.05), while DBP and alcohol consumption were significant, ORs 2.956 (95% CI: 1.249 - 6.997, p < 0.05) and 2.525 (95% CI: 1.062 - 6.002, p < 0.05) respectively. Multivariate analysis, showed that PP was significantly associated with CMBs, OR 3.194 (95% CI: 1.024 - 9.964, p < 0.05) in combination with SBP, DBP, gender, age, smoking and alcohol consumption. Taken together, the study showed that elevated PP is associated with CMB, but is not an independent risk factor for CMBs.展开更多
Purpose: We investigated the efficacy of potent or combined antibiotics in patients suffering bacterial infections secondary to H1N1 by retrospectively analyzing their bacterial pathogen spectrum and clinical characte...Purpose: We investigated the efficacy of potent or combined antibiotics in patients suffering bacterial infections secondary to H1N1 by retrospectively analyzing their bacterial pathogen spectrum and clinical characteristics. Methods: Multi-center retrospective analysis was performed using clinical data of H1N1 patients from 27 hospitals in Hebei Province, China, from November 1 to December 31, 2009. Results: Of 480 H1N1-infected patients enrolled from an inpatient clinic, 91 were positive for bacterial culture. Bacteria were detected in sputum culture at 7.00 ± 8.87 days post-admission. Compared with the negative group, the patients in the positive sputum culture group had a higher mean age and prevalence of basic diseases, higher APECHEII (Acute Physiology and Chronic Health Evaluation II) score within 24 hours of admission, longer hospital stays, and higher mortality. In total, 189 bacterial strains were isolated, with the majority of samples testing positive for Acinetobacter baumanii (47), Streptococcus viridians (26), or Pseudomonas aeruginosa (19). S. viridians was the major cause of infection within 3 days of admission, while A. baumanii infection was more prevalent from 4 days post-admission;there was a significant difference in the constituent ratio between the two pathogens (p 0.001). Compared with patients administered common antibiotics, the potent antibiotics group showed no significant difference in hospitalization time, time until bacterial detection, mortality, or detection ratio of resistant strains (p > 0.05). Conclusions: Complicated bacterial infection in H1N1 patients increases hospitalization time and mortality. Gram-negative bacilli and multi-resistant strains are the main sources of infection. Early administration of potent or combined antibiotics, even during the period of rapid onset, may not be suitable in H1N1-infected patients, particularly previously healthy young patients.展开更多
In this paper,we consider 3 D tomographic reconstruction for axially symmetric objects from a single radiograph formed by cone-beam X-rays.All contemporary density reconstruction methods in high-energy X-ray radiograp...In this paper,we consider 3 D tomographic reconstruction for axially symmetric objects from a single radiograph formed by cone-beam X-rays.All contemporary density reconstruction methods in high-energy X-ray radiography are based on the assumption that the cone beam can be treated as fan beams located at parallel planes perpendicular to the symmetric axis,so that the density of the whole object can be recovered layer by layer.Considering the relationship between different layers,we undertake the cone-beam global reconstruction to solve the ambiguity effect at the material interfaces of the reconstruction results.In view of the anisotropy of classical discrete total variations,a new discretization of total variation which yields sharp edges and has better isotropy is introduced in our reconstruction model.Furthermore,considering that the object density consists of continually changing parts and jumps,a high-order regularization term is introduced.The final hybrid regularization model is solved using the alternating proximal gradient method,which was recently applied in image processing.Density reconstruction results are presented for simulated radiographs,which shows that the proposed method has led to an improvement in terms of the preservation of edge location.展开更多
Being an exclusive construction material for lightweight rail vehicles,protection from pitting corrosion in harsh marine atmospheric environment in high humidity and Cl-ion concentration is critical for austenitic SUS...Being an exclusive construction material for lightweight rail vehicles,protection from pitting corrosion in harsh marine atmospheric environment in high humidity and Cl-ion concentration is critical for austenitic SUS 301L stainless steel(SS),especially when it inevitably suff ers from mechanical damages during post disposals.Herein,an innovative dry passivation method for austenitic SUS 301L SS was established in a closed air atmosphere at low temperature and constant pressure.The process parameters were optimized,and the passivation mechanism was explained using polarization curve,electrochemical impedance spectroscopy(EIS),X-ray photoelectron spectroscopy(XPS),and contact angle measurement.The pitting corrosion susceptibility of the passive fi lm prepared in a closed air chamber under 1.0×10^(5) Pa at 80℃ for 80 min was evaluated in 3.5%NaCl solution and exhibited higher pitting potential and corrosion resistance,lower passivity-maintaining current density,and wettability when compared with conventional nitric acid treatment.Besides,dry passivation facilitated the repairing of the surface structural defect itself and the post-processing damage,similar to the accelerated aging of fi lm.The decrease in oxygen concentration and convection-diff usion strengthened the preferential chromium oxidation to form a compact chromium-rich passive fi lm to resist the aggression of Cl-ion.展开更多
Objective:To determine the encephalic region correlated with epilepsy by manganese-enhanced MRI(MEMRI)and determine the correlation of epilepsy with calcium overloading.Methods:The cats were divided into two groups.Th...Objective:To determine the encephalic region correlated with epilepsy by manganese-enhanced MRI(MEMRI)and determine the correlation of epilepsy with calcium overloading.Methods:The cats were divided into two groups.The first group underwent EEG examination and ethological observation.The second group underwent MEMRI measurement.Signal enhanced encephalic regions were sectioned.Results:The achievement ratio of convulsive cats intramusclelarly injected with PTZ was 80%.MEMRI showed diffuse signal enhancement in the cerebral cortex of the cats with generalized tonic-clonic convulsive seizures compared with control animals.The enhancement rate of frontal-parietal-occipital lobe was 34.6% and 22.9% in temporal lobe compared with the control groups.Signal enhancement on frontal-parietal lobe persisted for 24 h after epileptic seizures were induced.The neurons of enhanced encephalic regions showed obvious degeneration and necrosis.Conclusion:Seizures can be induced in cats by intramuscular injection of PTZ(55 mg/kg).Frontal-parietal lobe is the correlated encephalic regions of epilepsy.MEMRI plays an important role in localizing and revealing pathogenesis of epileptic seizures.展开更多
In this work,the recycled Nd-Fe-B powders and regenerated Nd-Fe-B sintered magnets with low impurity content were successfully prepared from Nd-Fe-B magnet sludge via reduction diffusion(RD)method followed by a chemo-...In this work,the recycled Nd-Fe-B powders and regenerated Nd-Fe-B sintered magnets with low impurity content were successfully prepared from Nd-Fe-B magnet sludge via reduction diffusion(RD)method followed by a chemo-selective dissolution washing proc ess.The chemo-selective dissolution effect of various solution(deionized water,dilute acetic acid solution,NH_(4)Cl-methanol solution) was evaluated by impurity content and magnetic properties of the recycled Nd-Fe-B powder.The NH_(4)Cl-methanol solution can selectively remove impurities with minimal damage to the magnetic phase.Besides,the optimal NH_(4)Cl concentration and liquid-to-solid ratio were investigated.As a consequence,the contents of Ca,O,and H after optimal washing process are reduced to 0.07 wt%,0.31 wt% and 0.22 wt%,respectively.Hence,M_(3) Tis increased to 146.72 emu/g,which is 33% higher than that of the initial sludge.Then,the regenerated Nd-Fe-B sintered magnets with properties of B_(r)=11.66 kG,H_(cj)=16.49 kOe,and(BH)_(m)=31.78 MGOe were successfully prepared by mixing with 40 wt% Nd4Fe14B alloy powders.Compared with the corresponding regenerated magnets washed with deionized water,the remanence and coercivity are increased by 18% and 59%,respectively.展开更多
To examine the activation of organic acids on the leaching process of ion-adsorption type rare earth ore(IRE-ore), the leaching behavior of rare earth(RE) and zeta potential of IRE-ore were investigated in the absence...To examine the activation of organic acids on the leaching process of ion-adsorption type rare earth ore(IRE-ore), the leaching behavior of rare earth(RE) and zeta potential of IRE-ore were investigated in the absence and presence of carboxylic acids. The results show that all the tested organic acids(acetic acid,malonic acid, citric acid, tartaric acid, succinic acid, and malic acid) can promote RE extraction. At relatively high concentrations of organic acids, the activation efficiency of organic acids on RE extraction is generally consistent with their complexation ability; whereas at their low concentrations, the change of zeta potential on the IRE-ore surface with organic acid concentration and p H has a close association with RE extraction, which indicates that organic acids can impact the surface electrical property of IREore via their adsorption/desorption, and thereby increase/decrease the affinity of RE ions to IRE-ore.Therefore the influence of organic acids on the IRE-ore surface electrical property also plays an important role in RE extraction in addition to their complexation with RE ions.展开更多
The structural and magnetic properties were studied for recycling Nd-Fe-B powders from Nd-Fe-B sintered magnets sludge via reduction diffusion(RD)with calcium hydride(CaH_(2))particles.For comparison,traditional reduc...The structural and magnetic properties were studied for recycling Nd-Fe-B powders from Nd-Fe-B sintered magnets sludge via reduction diffusion(RD)with calcium hydride(CaH_(2))particles.For comparison,traditional reducing agent calcium granules were applied to prepare recycled Nd-Fe-B powders.Finer particle size and better size distribution as well as lower impurity content are achieved by using CaH_(2)instead of Ca.In detail,the average particle size of the recycled Nd-Fe-B powder is reduced from 4.66 to 3.43μm,and the bimodal distribution disappears.Moreover,the residual calcium content and oxygen content are reduced to about 0.080 wt%and 0.32 wt%.As a consequence,the roomtemperature magnetization of the CaH_(2)-recycled Nd-Fe-B powder is increased to 146.30 emu/g,6.8%and 33%,respectively,higher than that of Ca-reduced powder and the initial sludge.Further analysis indicates that CaH_(2)is able to reduce the sludge at lower tempe rature to fabricate well-dispersed,unifo rm recycled powder with high magnetization arising from a combination factors of its low melting point,low thermodynamic behavior,and the release of hydrogen during the reaction.展开更多
Main observation and conclusion A highly enantioselective 2,3-allenylation of acyclic and cyclicα-imino carboxylates via a synergistic bimetallic Pd/Cu catalysis with the same commercially available(R,Rp)-iPr-FOXAP(a...Main observation and conclusion A highly enantioselective 2,3-allenylation of acyclic and cyclicα-imino carboxylates via a synergistic bimetallic Pd/Cu catalysis with the same commercially available(R,Rp)-iPr-FOXAP(also as Phosferrox,(R,R)-[2-(4’-i-propyloxazolin-2’-yl)ferrocenyl]diphenyl phosphine)ligand for both metals affording optically active 2,3-butadienylα-amino acid derivatives in high to excellent yields with excellent enantioselectivities has been developed.展开更多
Background:The ongoing coronavirus disease 2019(COVID-19)pandemic has put radiologists at a higher risk of infection during the computer tomography(CT)examination for the patients.To help settling these problems,we ad...Background:The ongoing coronavirus disease 2019(COVID-19)pandemic has put radiologists at a higher risk of infection during the computer tomography(CT)examination for the patients.To help settling these problems,we adopted a remote-enabled and automated contactless imaging workflow for CT examination by the combination of intelligent guided robot and automatic positioning technology to reduce the potential exposure of radiologists to 2019 novel coronavirus(2019-nCoV)infection and to increase the examination efficiency,patient scanning accuracy and better image quality in chest CT imaging.Methods:From February 10 to April 12,2020,adult COVID-19 patients underwent chest CT examinations on a CT scanner using the same scan protocol except with the conventional imaging workflow(CW group)or an automatic contactless imaging workflow(AW group)in Wuhan Leishenshan Hospital(China)were retrospectively and prospectively enrolled in this study.The total examination time in two groups was recorded and compared.The patient compliance of breath holding,positioning accuracy,image noise and signal-to-noise ratio(SNR)were assessed by three experienced radiologists and compared between the two groups.Results:Compared with the CW group,the total positioning time of the AW group was reduced((118.0±20.0)s vs.(129.0±29.0)s,P=0.001),the proportion of scanning accuracy was higher(98%vs.93%),and the lung length had a significant difference((0.90±1.24)cm vs.(1.16±1.49)cm,P=0.009).For the lesions located in the pulmonary centrilobular and subpleural regions,the image noise in the AW group was significantly lower than that in the CW group(centrilobular region:(140.4±78.6)HU vs.(153.8±72.7)HU,P=0.028;subpleural region:(140.6±80.8)HU vs.(159.4±82.7)HU,P=0.010).For the lesions located in the peripheral,centrilobular and subpleural regions,SNR was significantly higher in the AW group than in the CW group(centrilobular region:6.6±4.3 vs.4.9±3.7,P=0.006;subpleural region:6.4±4.4 vs.4.8±4.0,P<0.001).Conclusions:The automatic contactless imaging workflow using intelligent guided robot and automatic posi-tioning technology allows for reducing the examination time and improving the patient’s compliance of breath holding,positioning accuracy and image quality in chest CT imaging.展开更多
Genomic imprinting is an epigenetic modification of DNA,whereby gene expression is restricted to either maternally or paternally inherited alleles.Imprinted genes(IGs)in the placenta and embryo are essential for growt...Genomic imprinting is an epigenetic modification of DNA,whereby gene expression is restricted to either maternally or paternally inherited alleles.Imprinted genes(IGs)in the placenta and embryo are essential for growth regulation and nutrient supply.However,despite being an important nutrition delivery organ,studies on mammary gland genomic imprinting remain limited.In this study,we found that both the number of IGs and their expression levels decreased during development of the mouse mammary gland.IG expression was lineage-specific and related to mammary gland development and lactation.Meta-analysis of single-cell RNA sequencing data revealed that mammary gland IGs were co-expressed in a network that regulated cell sternness and differentiation,which was confirmed by our functional studies.Accordingly,our data indicated that IGs were essential for the self-renewal of mammary gland stem cells and IG decline was correlated with mammary gland maturity.Taken together,our findings revealed the importance of IGs in a poorly studied nutrition-related organ,i.e.the mammary gland,thus providing a reference for further studies on genomic imprinting.展开更多
In recent years,with the development of artificial intelligence,especially deep learning technology,researches on automatic detection of cerebrovascular diseases on medical images have made tremendous progress and the...In recent years,with the development of artificial intelligence,especially deep learning technology,researches on automatic detection of cerebrovascular diseases on medical images have made tremendous progress and these models are gradually entering into clinical practice.However,because of the complexity and flexibility of the deep learning algorithms,these researches have great variability on model building,validation process,performance description and results interpretation.The lack of a reliable,consistent,standardized design protocol has,to a certain extent,affected the progress of clinical translation and technology development of computer aided detection systems.After reviewing a large number of literatures and extensive discussion with domestic experts,this position paper put forward recommendations of standardized design on the key steps of deep learning-based automatic image detection models for cerebrovascular diseases.With further research and application expansion,this position paper would continue to be updated and gradually extended to evaluate the generalizability and clinical application efficacy of such tools.展开更多
Out-of-step oscillation separation devices based on apparent impedance angle trajectory are widely used in the power grid in China,and their reliability is of great importance.In this paper,the influence mechanism of ...Out-of-step oscillation separation devices based on apparent impedance angle trajectory are widely used in the power grid in China,and their reliability is of great importance.In this paper,the influence mechanism of series compensation on apparent impedance angle trajectory is analyzed.It reveals that series compensation capacitors reduce the equivalent impedance angle and consequently the apparent impedance angle cannot pass through all four zones,resulting in the risk of failure for the separation devices.A revised method of apparent impedance angle based on compensation principle is discussed,and then an improved out-of-step oscillation detection criterion is proposed.In view of the fact that the apparent impedance angle at the moment of maximum current is equal to the equivalent impedance angle during an oscillation process,a practical algorithm based on the compensated apparent impedance angle is proposed.RTDS tests are conducted to verify the effectiveness of the new criterion,considering transmission lines with a high series compensation level.展开更多
During the highly infectious pandemic of coronavirus disease 2019(COVID-19),artificial intelligence(AI)has provided support in addressing challenges and accelerating achievements in controlling this public health cris...During the highly infectious pandemic of coronavirus disease 2019(COVID-19),artificial intelligence(AI)has provided support in addressing challenges and accelerating achievements in controlling this public health crisis.It has been applied in fields varying from outbreak forecasting to patient management and drug/vaccine development.In this paper,we specifically review the current status of AI-based approaches for patient management.Limitations and challenges still exist,and further needs are highlighted.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.52261037)self-deployed Projects of Ganjiang Innovation Academy,Chinese Academy of Sciences(Grant No.E055B002)+2 种基金the Project of Baotou City Science and Technology(Grant No.XM2022BT04)the Key Research Program of the Chinese Academy of Sciences(Grant No.ZDRW-CN-2021-3)the Key Research Project of Jiangxi Province(Grant No.20203ABC28W006)。
文摘As the channel for grain boundary diffusion(GBD)in Nd–Fe–B magnets,grain boundary(GB)phases have a very important effect on GBD.As doping elements that are commonly used to regulate the GB phases in Nd–Fe–B sintered magnets,the influences of Ga and Zr on GBD were investigated in this work.The results show that the Zr-doped magnet has the highest coercivity increment(7.97 kOe)by GBD,which is almost twice that of the Ga-doped magnet(4.32 kOe)and the magnet without Ga and Zr(3.24 kOe).Microstructure analysis shows that ZrB_(2)formed in the Zr-doped magnet plays a key role in increasing the diffusion depth.A continuous diffusion channel in the magnet can form because of the presence of ZrB_(2).ZrB_(2)can also increase the defect concentration in GB phases,which can facilitate GBD.Although Ga can also improve the diffusion depth,its effect is not very obvious.The micromagnetic simulation based on the experimental results also proves that the distribution of Tb in the Zr-doped magnet after GBD is beneficial to coercivity.This study reveals that the doping elements Ga and Zr in Nd–Fe–B play an important role in GBD,and could provide a new perspective for researchers to improve the effects of GBD.
基金supported by the National Natural Science Foundation of China(Grant No.11675021)the Youth Fund Project of Zhejiang Lab(Grant No.K2023MG0AA08).
文摘Diagnosis of fluids is extremely significant at high temperatures and high pressures.As an advanced imaging technique,high-energy proton radiography has great potential for application to the diagnosis of high-density fluids.In high-energy proton radiography,an angular collimator can control the proton flux and thus enable material diagnosis and reconstruction of density.In this paper,we propose a multimaterial diagnostic method using angular collimators.The method is verified by reconstructing the density distribution from the proton flux obtained via theoretical calculations and numerical simulations.We simulate a 20 GeV proton imaging system using the Geant4 software toolkit and obtain the characteristic parameters of single-material objects.We design several concentric spherical objects to verify the method.We discuss its application to detonation tests.The results show that this method can determine the material and boundary information about each component of a multi-material object.Thus,it can be used to diagnose a mixed material and reconstruct densities in a detonation.
文摘Recent developments in brain magnetic resonance imaging using advanced Susceptibility Weighted Imaging (SWI) have significantly increased the detection and prevalence of Cerebral Microbleeds (CMBs). Here, we aimed to explore the association between Pulse Pressure (PP) and CMBs. Having been implicated in various arteriopathies, we hypothesized that elevated PP could also be a risk for CMBs. A retrospective case-control study was conducted from August 2021 to September 2022 at Zhongnan Hospital of Wuhan University China. Extracted data were analyzed in SPSS. Chi-square test, binary logistic regression, and Spearman’s correlation analysis were conducted.104 patients were analyzed. Univariate analysis showed no significant association between PP and CMBs, OR 1.65 (95% CI: 0.737 - 3.694;p > 0.05), while DBP and alcohol consumption were significant, ORs 2.956 (95% CI: 1.249 - 6.997, p < 0.05) and 2.525 (95% CI: 1.062 - 6.002, p < 0.05) respectively. Multivariate analysis, showed that PP was significantly associated with CMBs, OR 3.194 (95% CI: 1.024 - 9.964, p < 0.05) in combination with SBP, DBP, gender, age, smoking and alcohol consumption. Taken together, the study showed that elevated PP is associated with CMB, but is not an independent risk factor for CMBs.
文摘Purpose: We investigated the efficacy of potent or combined antibiotics in patients suffering bacterial infections secondary to H1N1 by retrospectively analyzing their bacterial pathogen spectrum and clinical characteristics. Methods: Multi-center retrospective analysis was performed using clinical data of H1N1 patients from 27 hospitals in Hebei Province, China, from November 1 to December 31, 2009. Results: Of 480 H1N1-infected patients enrolled from an inpatient clinic, 91 were positive for bacterial culture. Bacteria were detected in sputum culture at 7.00 ± 8.87 days post-admission. Compared with the negative group, the patients in the positive sputum culture group had a higher mean age and prevalence of basic diseases, higher APECHEII (Acute Physiology and Chronic Health Evaluation II) score within 24 hours of admission, longer hospital stays, and higher mortality. In total, 189 bacterial strains were isolated, with the majority of samples testing positive for Acinetobacter baumanii (47), Streptococcus viridians (26), or Pseudomonas aeruginosa (19). S. viridians was the major cause of infection within 3 days of admission, while A. baumanii infection was more prevalent from 4 days post-admission;there was a significant difference in the constituent ratio between the two pathogens (p 0.001). Compared with patients administered common antibiotics, the potent antibiotics group showed no significant difference in hospitalization time, time until bacterial detection, mortality, or detection ratio of resistant strains (p > 0.05). Conclusions: Complicated bacterial infection in H1N1 patients increases hospitalization time and mortality. Gram-negative bacilli and multi-resistant strains are the main sources of infection. Early administration of potent or combined antibiotics, even during the period of rapid onset, may not be suitable in H1N1-infected patients, particularly previously healthy young patients.
基金supported by National Postdoctoral Program for Innovative Talents(BX201700038)supported by NSFC(11571003)+1 种基金supported by NSFC(11675021)supported by Beijing Natural Science Foundation(Z180002)。
文摘In this paper,we consider 3 D tomographic reconstruction for axially symmetric objects from a single radiograph formed by cone-beam X-rays.All contemporary density reconstruction methods in high-energy X-ray radiography are based on the assumption that the cone beam can be treated as fan beams located at parallel planes perpendicular to the symmetric axis,so that the density of the whole object can be recovered layer by layer.Considering the relationship between different layers,we undertake the cone-beam global reconstruction to solve the ambiguity effect at the material interfaces of the reconstruction results.In view of the anisotropy of classical discrete total variations,a new discretization of total variation which yields sharp edges and has better isotropy is introduced in our reconstruction model.Furthermore,considering that the object density consists of continually changing parts and jumps,a high-order regularization term is introduced.The final hybrid regularization model is solved using the alternating proximal gradient method,which was recently applied in image processing.Density reconstruction results are presented for simulated radiographs,which shows that the proposed method has led to an improvement in terms of the preservation of edge location.
基金Supported by the CRRC Changchun Railway Vehicles Co.,Ltd.(No.GYHB(12)-01-00-014(067))the Natural Science Foundation of Shandong Province,China(No.ZR2020MB080)。
文摘Being an exclusive construction material for lightweight rail vehicles,protection from pitting corrosion in harsh marine atmospheric environment in high humidity and Cl-ion concentration is critical for austenitic SUS 301L stainless steel(SS),especially when it inevitably suff ers from mechanical damages during post disposals.Herein,an innovative dry passivation method for austenitic SUS 301L SS was established in a closed air atmosphere at low temperature and constant pressure.The process parameters were optimized,and the passivation mechanism was explained using polarization curve,electrochemical impedance spectroscopy(EIS),X-ray photoelectron spectroscopy(XPS),and contact angle measurement.The pitting corrosion susceptibility of the passive fi lm prepared in a closed air chamber under 1.0×10^(5) Pa at 80℃ for 80 min was evaluated in 3.5%NaCl solution and exhibited higher pitting potential and corrosion resistance,lower passivity-maintaining current density,and wettability when compared with conventional nitric acid treatment.Besides,dry passivation facilitated the repairing of the surface structural defect itself and the post-processing damage,similar to the accelerated aging of fi lm.The decrease in oxygen concentration and convection-diff usion strengthened the preferential chromium oxidation to form a compact chromium-rich passive fi lm to resist the aggression of Cl-ion.
文摘Objective:To determine the encephalic region correlated with epilepsy by manganese-enhanced MRI(MEMRI)and determine the correlation of epilepsy with calcium overloading.Methods:The cats were divided into two groups.The first group underwent EEG examination and ethological observation.The second group underwent MEMRI measurement.Signal enhanced encephalic regions were sectioned.Results:The achievement ratio of convulsive cats intramusclelarly injected with PTZ was 80%.MEMRI showed diffuse signal enhancement in the cerebral cortex of the cats with generalized tonic-clonic convulsive seizures compared with control animals.The enhancement rate of frontal-parietal-occipital lobe was 34.6% and 22.9% in temporal lobe compared with the control groups.Signal enhancement on frontal-parietal lobe persisted for 24 h after epileptic seizures were induced.The neurons of enhanced encephalic regions showed obvious degeneration and necrosis.Conclusion:Seizures can be induced in cats by intramuscular injection of PTZ(55 mg/kg).Frontal-parietal lobe is the correlated encephalic regions of epilepsy.MEMRI plays an important role in localizing and revealing pathogenesis of epileptic seizures.
基金supported by the National Key R&D Program of China(2019YFA0906003)the National Natural Science Foundation of China(32000989)+5 种基金China Postdoctoral Science Foundation Grant(2020M682911 and 2020M670051ZX)Guangdong Special Support Program(2021JC06Y578)the Shenzhen Municipal Government of China(JCYJ20200109120016553,CJGJZD20200617102403009,and RCBS20210706092256081)the Sanming Project of Shenzhen Health and Family Planning Commission(SZSM202011017)Shenzhen Institute of Synthetic Biology Scientific Research Program(ZTXM20214005)the Shenzhen High-level Hospital Construction Fund。
基金Project supported by the National Key R&D Program of China (2021YFB3500801)the National Natural Science Foundation of China(52271161)+5 种基金the Science and Technology Program of Anhui Province(201903a07020002)General Program of Science and Technology Development Project of Beijing Municipal Education Commission (KM202010005009)"QiHang Programme"for Faculty of Materials and Manufacturing,BJUT (QH202211)Program of Top Disciplines Construction in Beijing (PXM2019_014204_500031)Key Laboratory of Ionic Rare Earth Resources and Environment,Ministry of Natural Resources of the People’s Republic of China (2022IRERE302)the State Key Laboratory of Rare Earth Permanent Magnetic Materials Opening Foundation(SKLREPM170F02)。
文摘In this work,the recycled Nd-Fe-B powders and regenerated Nd-Fe-B sintered magnets with low impurity content were successfully prepared from Nd-Fe-B magnet sludge via reduction diffusion(RD)method followed by a chemo-selective dissolution washing proc ess.The chemo-selective dissolution effect of various solution(deionized water,dilute acetic acid solution,NH_(4)Cl-methanol solution) was evaluated by impurity content and magnetic properties of the recycled Nd-Fe-B powder.The NH_(4)Cl-methanol solution can selectively remove impurities with minimal damage to the magnetic phase.Besides,the optimal NH_(4)Cl concentration and liquid-to-solid ratio were investigated.As a consequence,the contents of Ca,O,and H after optimal washing process are reduced to 0.07 wt%,0.31 wt% and 0.22 wt%,respectively.Hence,M_(3) Tis increased to 146.72 emu/g,which is 33% higher than that of the initial sludge.Then,the regenerated Nd-Fe-B sintered magnets with properties of B_(r)=11.66 kG,H_(cj)=16.49 kOe,and(BH)_(m)=31.78 MGOe were successfully prepared by mixing with 40 wt% Nd4Fe14B alloy powders.Compared with the corresponding regenerated magnets washed with deionized water,the remanence and coercivity are increased by 18% and 59%,respectively.
基金Project supported by National Natural Science Foundation of China(51604128)
文摘To examine the activation of organic acids on the leaching process of ion-adsorption type rare earth ore(IRE-ore), the leaching behavior of rare earth(RE) and zeta potential of IRE-ore were investigated in the absence and presence of carboxylic acids. The results show that all the tested organic acids(acetic acid,malonic acid, citric acid, tartaric acid, succinic acid, and malic acid) can promote RE extraction. At relatively high concentrations of organic acids, the activation efficiency of organic acids on RE extraction is generally consistent with their complexation ability; whereas at their low concentrations, the change of zeta potential on the IRE-ore surface with organic acid concentration and p H has a close association with RE extraction, which indicates that organic acids can impact the surface electrical property of IREore via their adsorption/desorption, and thereby increase/decrease the affinity of RE ions to IRE-ore.Therefore the influence of organic acids on the IRE-ore surface electrical property also plays an important role in RE extraction in addition to their complexation with RE ions.
基金Project supported by the National Key R&D Project(2020YFC1909004)Science and Technology Program of Anhui Province(201903a07020002)+1 种基金Program of Top Disciplines Construction in Beijing(PXM2019_014204_500031)State Key Laboratory of Rare Earth Permanent Magnetic Materials Opening Foundation(SKLREPM17OF02)。
文摘The structural and magnetic properties were studied for recycling Nd-Fe-B powders from Nd-Fe-B sintered magnets sludge via reduction diffusion(RD)with calcium hydride(CaH_(2))particles.For comparison,traditional reducing agent calcium granules were applied to prepare recycled Nd-Fe-B powders.Finer particle size and better size distribution as well as lower impurity content are achieved by using CaH_(2)instead of Ca.In detail,the average particle size of the recycled Nd-Fe-B powder is reduced from 4.66 to 3.43μm,and the bimodal distribution disappears.Moreover,the residual calcium content and oxygen content are reduced to about 0.080 wt%and 0.32 wt%.As a consequence,the roomtemperature magnetization of the CaH_(2)-recycled Nd-Fe-B powder is increased to 146.30 emu/g,6.8%and 33%,respectively,higher than that of Ca-reduced powder and the initial sludge.Further analysis indicates that CaH_(2)is able to reduce the sludge at lower tempe rature to fabricate well-dispersed,unifo rm recycled powder with high magnetization arising from a combination factors of its low melting point,low thermodynamic behavior,and the release of hydrogen during the reaction.
基金Financial support from the National Natural Science Foundation of China(Grant No.21690063 to S.M.,and Grant No.21901158 to X.H.)is greatly appreciated.We thank Mr.Huanan Wang in this group for reproducing the results of(R)-3'd,(Rm-3and(R)-17k,presented in Tables 2,3,and 4,respectively.
文摘Main observation and conclusion A highly enantioselective 2,3-allenylation of acyclic and cyclicα-imino carboxylates via a synergistic bimetallic Pd/Cu catalysis with the same commercially available(R,Rp)-iPr-FOXAP(also as Phosferrox,(R,R)-[2-(4’-i-propyloxazolin-2’-yl)ferrocenyl]diphenyl phosphine)ligand for both metals affording optically active 2,3-butadienylα-amino acid derivatives in high to excellent yields with excellent enantioselectivities has been developed.
基金This study was supported by the National Key Research and Development Plan of China(Grant No.2017YFC0108803)the National Natural Science Foundation of China(Grant Nos.81771819 and 81801667).
文摘Background:The ongoing coronavirus disease 2019(COVID-19)pandemic has put radiologists at a higher risk of infection during the computer tomography(CT)examination for the patients.To help settling these problems,we adopted a remote-enabled and automated contactless imaging workflow for CT examination by the combination of intelligent guided robot and automatic positioning technology to reduce the potential exposure of radiologists to 2019 novel coronavirus(2019-nCoV)infection and to increase the examination efficiency,patient scanning accuracy and better image quality in chest CT imaging.Methods:From February 10 to April 12,2020,adult COVID-19 patients underwent chest CT examinations on a CT scanner using the same scan protocol except with the conventional imaging workflow(CW group)or an automatic contactless imaging workflow(AW group)in Wuhan Leishenshan Hospital(China)were retrospectively and prospectively enrolled in this study.The total examination time in two groups was recorded and compared.The patient compliance of breath holding,positioning accuracy,image noise and signal-to-noise ratio(SNR)were assessed by three experienced radiologists and compared between the two groups.Results:Compared with the CW group,the total positioning time of the AW group was reduced((118.0±20.0)s vs.(129.0±29.0)s,P=0.001),the proportion of scanning accuracy was higher(98%vs.93%),and the lung length had a significant difference((0.90±1.24)cm vs.(1.16±1.49)cm,P=0.009).For the lesions located in the pulmonary centrilobular and subpleural regions,the image noise in the AW group was significantly lower than that in the CW group(centrilobular region:(140.4±78.6)HU vs.(153.8±72.7)HU,P=0.028;subpleural region:(140.6±80.8)HU vs.(159.4±82.7)HU,P=0.010).For the lesions located in the peripheral,centrilobular and subpleural regions,SNR was significantly higher in the AW group than in the CW group(centrilobular region:6.6±4.3 vs.4.9±3.7,P=0.006;subpleural region:6.4±4.4 vs.4.8±4.0,P<0.001).Conclusions:The automatic contactless imaging workflow using intelligent guided robot and automatic posi-tioning technology allows for reducing the examination time and improving the patient’s compliance of breath holding,positioning accuracy and image quality in chest CT imaging.
基金This work was supported by the National Key Research and Development Program of China(2016YFA0100900)the National Natural Science Foundation of China(U1802285,31970612,81871403,and 81571738)+3 种基金Yunnan Applied Basic Research Key Projects(2018FA002 and 2015HA026)Key Research and Development Program of Zhejiang Province(2019C03014)Open Project from the State Key Laboratory of Genetic Resources and Evolution(GREKF20-0A)Fundamental Research Funds for the Central Universities.
文摘Genomic imprinting is an epigenetic modification of DNA,whereby gene expression is restricted to either maternally or paternally inherited alleles.Imprinted genes(IGs)in the placenta and embryo are essential for growth regulation and nutrient supply.However,despite being an important nutrition delivery organ,studies on mammary gland genomic imprinting remain limited.In this study,we found that both the number of IGs and their expression levels decreased during development of the mouse mammary gland.IG expression was lineage-specific and related to mammary gland development and lactation.Meta-analysis of single-cell RNA sequencing data revealed that mammary gland IGs were co-expressed in a network that regulated cell sternness and differentiation,which was confirmed by our functional studies.Accordingly,our data indicated that IGs were essential for the self-renewal of mammary gland stem cells and IG decline was correlated with mammary gland maturity.Taken together,our findings revealed the importance of IGs in a poorly studied nutrition-related organ,i.e.the mammary gland,thus providing a reference for further studies on genomic imprinting.
基金Project supported by the Key Program of the National Natural Sci-ence Foundation of China(Grant Nos.81830057 and 82230068)the Young Scientists Fund of the National Natural Science Foundation of China(Grant No.82102155).
文摘In recent years,with the development of artificial intelligence,especially deep learning technology,researches on automatic detection of cerebrovascular diseases on medical images have made tremendous progress and these models are gradually entering into clinical practice.However,because of the complexity and flexibility of the deep learning algorithms,these researches have great variability on model building,validation process,performance description and results interpretation.The lack of a reliable,consistent,standardized design protocol has,to a certain extent,affected the progress of clinical translation and technology development of computer aided detection systems.After reviewing a large number of literatures and extensive discussion with domestic experts,this position paper put forward recommendations of standardized design on the key steps of deep learning-based automatic image detection models for cerebrovascular diseases.With further research and application expansion,this position paper would continue to be updated and gradually extended to evaluate the generalizability and clinical application efficacy of such tools.
基金supported by the science and technology project of State Grid Corporation of China (Security Protection Technology of Embedded Components and Control Units in Power System Terminal,No.5100-201941446A-0-0-00).
文摘Out-of-step oscillation separation devices based on apparent impedance angle trajectory are widely used in the power grid in China,and their reliability is of great importance.In this paper,the influence mechanism of series compensation on apparent impedance angle trajectory is analyzed.It reveals that series compensation capacitors reduce the equivalent impedance angle and consequently the apparent impedance angle cannot pass through all four zones,resulting in the risk of failure for the separation devices.A revised method of apparent impedance angle based on compensation principle is discussed,and then an improved out-of-step oscillation detection criterion is proposed.In view of the fact that the apparent impedance angle at the moment of maximum current is equal to the equivalent impedance angle during an oscillation process,a practical algorithm based on the compensated apparent impedance angle is proposed.RTDS tests are conducted to verify the effectiveness of the new criterion,considering transmission lines with a high series compensation level.
基金This research was funded by National Key Research and Development Program of China(Grant No.2020YFC0845500).
文摘During the highly infectious pandemic of coronavirus disease 2019(COVID-19),artificial intelligence(AI)has provided support in addressing challenges and accelerating achievements in controlling this public health crisis.It has been applied in fields varying from outbreak forecasting to patient management and drug/vaccine development.In this paper,we specifically review the current status of AI-based approaches for patient management.Limitations and challenges still exist,and further needs are highlighted.
