The gelation of crude oil with high wax and asphaltene content at low temperatures often results in the block of transportation pipeline in Africa. In recent years, it was reported that surface hydrophobicmodified nan...The gelation of crude oil with high wax and asphaltene content at low temperatures often results in the block of transportation pipeline in Africa. In recent years, it was reported that surface hydrophobicmodified nanoparticles have important applications in crude oil flow modification. In this work, four kinds of core-shell hybride nanoparticles by grafting poly(octadecyl, docosyl acrylate) and poly(acrylate-α-olefin) onto the surface of nano-sized SiO_(2) were synthesized by grafting polymerization method.The chemical structure of nanoparticles was analyzed by Fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM) and thermogravimetric analysis(TGA). The rheological behaviors of crude oil and precipitation of asphaltenes in the presence of nanoparticles were studied by measuring the viscose-temperature relationship curve, the cumulative wax precipitation amount, and morphology of waxes and asphaltenes. The results indicate that the docosyl polyacrylate@SiO_(2) nanoparticle(PDA@SiO_(2)) can reduce the cumulative wax precipitation amount of crude oil by 72.8%, decline the viscosity of crude oil by 85.6% at 20℃, reduce the average size of wax crystals by 89.7%, and inhibit the agglomeration of asphaltene by 74.8%. Therefore, the nanoparticles not only adjust the crystalline behaviors of waxes, but also inhibit the agglomeration of asphaltenes. Apparently, core-shell hybride nanoparticles provides more heterogeneous nucleation sites for the crystallization of wax molecules,thus inhibiting the formation of three-dimensional network structure. The core-shell polymer@SiO_(2) hybride nanoparticles are one of promising additives for inhibiting crystallization of waxes and agglomeration of asphaltenes in crude oil.展开更多
BACKGROUND Wireless capsule endoscopy(WCE)has become an important noninvasive and portable tool for diagnosing digestive tract diseases and has been propelled by advancements in medical imaging technology.However,the ...BACKGROUND Wireless capsule endoscopy(WCE)has become an important noninvasive and portable tool for diagnosing digestive tract diseases and has been propelled by advancements in medical imaging technology.However,the complexity of the digestive tract structure,and the diversity of lesion types,results in different sites and types of lesions distinctly appearing in the images,posing a challenge for the accurate identification of digestive tract diseases.AIM To propose a deep learning-based lesion detection model to automatically identify and accurately label digestive tract lesions,thereby improving the diagnostic efficiency of doctors,and creating significant clinical application value.METHODS In this paper,we propose a neural network model,WCE_Detection,for the accurate detection and classification of 23 classes of digestive tract lesion images.First,since multicategory lesion images exhibit various shapes and scales,a multidetection head strategy is adopted in the object detection network to increase the model's robustness for multiscale lesion detection.Moreover,a bidirectional feature pyramid network(BiFPN)is introduced,which effectively fuses shallow semantic features by adding skip connections,significantly reducing the detection error rate.On the basis of the above,we utilize the Swin Transformer with its unique self-attention mechanism and hierarchical structure in conjunction with the BiFPN feature fusion technique to enhance the feature representation of multicategory lesion images.RESULTS The model constructed in this study achieved an mAP50 of 91.5%for detecting 23 lesions.More than eleven single-category lesions achieved an mAP50 of over 99.4%,and more than twenty lesions had an mAP50 value of over 80%.These results indicate that the model outperforms other state-of-the-art models in the end-to-end integrated detection of human digestive tract lesion images.CONCLUSION The deep learning-based object detection network detects multiple digestive tract lesions in WCE images with high accuracy,improving the diagnostic efficiency of doctors,and demonstrating significant clinical application value.展开更多
BACKGROUND The emergency department(ED)plays a critical role in establishing artificial airways and implementing mechanical ventilation.Managing airbags in the ED presents a prime opportunity to mitigate the risk of v...BACKGROUND The emergency department(ED)plays a critical role in establishing artificial airways and implementing mechanical ventilation.Managing airbags in the ED presents a prime opportunity to mitigate the risk of ventilator-associated pneumonia.Nonetheless,existing research has largely overlooked the understanding,beliefs,and practical dimensions of airway airbag management among ED nurses,with a predominant focus on intensive care unit nurses.AIM To investigate the current status of ED nurses'knowledge,beliefs,and practical behaviors in airway airbag management and their influencing factors.METHODS A survey was conducted from July 10th to August 10th,2023,using convenience sampling on 520 ED nurses from 15 tertiary hospitals and 5 sary hospitals in Shanghai.Pathway analysis was utilized to analyze the influencing factors.RESULTS The scores for ED nurses'airway airbag management knowledge were 60.26±23.00,belief was 88.65±13.36,and behavior was 75.10±19.84.The main influencing factors of airbag management knowledge included participation in specialized nurse or mechanical ventilation training,department,and work experience in the department.Influencing factors of airbag management belief comprised knowledge,department,and participation in specialized nurse or mechanical ventilation training.Primary influencing factors of airbag management behavior included knowledge,belief,department,participation in specialized nurse or mechanical ventilation training,and professional title.The belief in airbag management among ED nurses acted as a partial mediator between knowledge and behavior,with a total effect value of 0.513,and an indirect effect of 0.085,constituting 16.6%of the total effect.CONCLUSION ED nurses exhibit a positive attitude toward airbag management with relatively standardized practices,yet there remains room for improvement in their knowledge levels.Nursing managers should implement interventions tailored to the characteristics of ED nurses'airbag management knowledge,beliefs,and practices to enhance their airbag management proficiency.展开更多
The compression behavior of the lattice-walled tubes under variable strain rates are investigated by numerical simulation,and the stress-strain relationship of the structure under quasi-static loading is theoretically...The compression behavior of the lattice-walled tubes under variable strain rates are investigated by numerical simulation,and the stress-strain relationship of the structure under quasi-static loading is theoretically analyzed.The finite element software LS-DYNA is used to simulate the structure established by the beam element,and the critical impact velocity is obtained when the structure collapses layer by layer.According to the plastic hinge theory and considering the combined action of the beam's bending moment and axial force in the structure,the stress-strain relationship of the structure under quasi-static loading is derived and compared with the experimental results.The numerical simulation results reveal that the structure of the single-layer gradient tube(SGC)does not undergo shear deformation under quasi-static and low-speed impact.The critical speed of the gradient square tube(GS)is higher than that of a cylindrical tube.The theoretical model can correctly reflect the mechanical response of the structure under uniaxial compression.展开更多
The synthesis of colloidal telluride semiconductor nanocrystals(CT-SNCs)is more challenging than that of chalcogenides,due to the smaller electron affinity of tellurium than that of sulfur and selenium,which is attrib...The synthesis of colloidal telluride semiconductor nanocrystals(CT-SNCs)is more challenging than that of chalcogenides,due to the smaller electron affinity of tellurium than that of sulfur and selenium,which is attributed to its metalloid property.While some new potential strategies were developing with the increasing demand of CT-SNCs,the cation exchange reaction(CER)has particularly become a new strategy to synthesize highquality CT-SNCs and their corresponded hetero-nanostructures.This review summarizes the synthesis strategies of CT-SNCs,including traditional methods and new methods with emphasis on CERs,and their resulting CTSNCs with well-controlling size,shape,composition,crystallization and hetero-interfaces cooperatively.The progressive synthesis methods give rise to the excellent optical properties of CT-SNCs.This review also covers the recent progress of their applications in the field of photoelectric detection,catalysis,batteries and biology.The new hybrid CT-SNCs nanostructures are also emphasized and systematically discussed due to their enhanced properties.展开更多
A diquinoxalinopyrene （DQP） derivative and the corresponding oligomers （PDQPs） with Mn of ca. 3300, 4200, 5600, and 7300 have been synthesized. It is found that the band gaps and highest occupied molecular orbital...A diquinoxalinopyrene （DQP） derivative and the corresponding oligomers （PDQPs） with Mn of ca. 3300, 4200, 5600, and 7300 have been synthesized. It is found that the band gaps and highest occupied molecular orbital （HOMO）/lowest unoccupied molecular orbital （LUMO） levels between DQP and its homopolymers only have a slight difference, implying a limited conjugation extension achieved from unimer to heptamer. The DFT calculation is in accordance with the experimental results. It reveals that the nodal planes are across the 2,11-positions in the LUMO and/or HOMO of DQP, dimer and trimer, which can be used to explain this special phenomenon.展开更多
基金Financial support by project of China Petroleum Engineering Corp., Ltd (CPEC), Study on microstructural regulation of polyacrylate and applying as pour-point depressant for crude oil (2021ZYGC-01-01)。
文摘The gelation of crude oil with high wax and asphaltene content at low temperatures often results in the block of transportation pipeline in Africa. In recent years, it was reported that surface hydrophobicmodified nanoparticles have important applications in crude oil flow modification. In this work, four kinds of core-shell hybride nanoparticles by grafting poly(octadecyl, docosyl acrylate) and poly(acrylate-α-olefin) onto the surface of nano-sized SiO_(2) were synthesized by grafting polymerization method.The chemical structure of nanoparticles was analyzed by Fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM) and thermogravimetric analysis(TGA). The rheological behaviors of crude oil and precipitation of asphaltenes in the presence of nanoparticles were studied by measuring the viscose-temperature relationship curve, the cumulative wax precipitation amount, and morphology of waxes and asphaltenes. The results indicate that the docosyl polyacrylate@SiO_(2) nanoparticle(PDA@SiO_(2)) can reduce the cumulative wax precipitation amount of crude oil by 72.8%, decline the viscosity of crude oil by 85.6% at 20℃, reduce the average size of wax crystals by 89.7%, and inhibit the agglomeration of asphaltene by 74.8%. Therefore, the nanoparticles not only adjust the crystalline behaviors of waxes, but also inhibit the agglomeration of asphaltenes. Apparently, core-shell hybride nanoparticles provides more heterogeneous nucleation sites for the crystallization of wax molecules,thus inhibiting the formation of three-dimensional network structure. The core-shell polymer@SiO_(2) hybride nanoparticles are one of promising additives for inhibiting crystallization of waxes and agglomeration of asphaltenes in crude oil.
基金Supported by The Science and Technology Development Center of The Ministry of Education,No.2022BC004。
文摘BACKGROUND Wireless capsule endoscopy(WCE)has become an important noninvasive and portable tool for diagnosing digestive tract diseases and has been propelled by advancements in medical imaging technology.However,the complexity of the digestive tract structure,and the diversity of lesion types,results in different sites and types of lesions distinctly appearing in the images,posing a challenge for the accurate identification of digestive tract diseases.AIM To propose a deep learning-based lesion detection model to automatically identify and accurately label digestive tract lesions,thereby improving the diagnostic efficiency of doctors,and creating significant clinical application value.METHODS In this paper,we propose a neural network model,WCE_Detection,for the accurate detection and classification of 23 classes of digestive tract lesion images.First,since multicategory lesion images exhibit various shapes and scales,a multidetection head strategy is adopted in the object detection network to increase the model's robustness for multiscale lesion detection.Moreover,a bidirectional feature pyramid network(BiFPN)is introduced,which effectively fuses shallow semantic features by adding skip connections,significantly reducing the detection error rate.On the basis of the above,we utilize the Swin Transformer with its unique self-attention mechanism and hierarchical structure in conjunction with the BiFPN feature fusion technique to enhance the feature representation of multicategory lesion images.RESULTS The model constructed in this study achieved an mAP50 of 91.5%for detecting 23 lesions.More than eleven single-category lesions achieved an mAP50 of over 99.4%,and more than twenty lesions had an mAP50 value of over 80%.These results indicate that the model outperforms other state-of-the-art models in the end-to-end integrated detection of human digestive tract lesion images.CONCLUSION The deep learning-based object detection network detects multiple digestive tract lesions in WCE images with high accuracy,improving the diagnostic efficiency of doctors,and demonstrating significant clinical application value.
文摘BACKGROUND The emergency department(ED)plays a critical role in establishing artificial airways and implementing mechanical ventilation.Managing airbags in the ED presents a prime opportunity to mitigate the risk of ventilator-associated pneumonia.Nonetheless,existing research has largely overlooked the understanding,beliefs,and practical dimensions of airway airbag management among ED nurses,with a predominant focus on intensive care unit nurses.AIM To investigate the current status of ED nurses'knowledge,beliefs,and practical behaviors in airway airbag management and their influencing factors.METHODS A survey was conducted from July 10th to August 10th,2023,using convenience sampling on 520 ED nurses from 15 tertiary hospitals and 5 sary hospitals in Shanghai.Pathway analysis was utilized to analyze the influencing factors.RESULTS The scores for ED nurses'airway airbag management knowledge were 60.26±23.00,belief was 88.65±13.36,and behavior was 75.10±19.84.The main influencing factors of airbag management knowledge included participation in specialized nurse or mechanical ventilation training,department,and work experience in the department.Influencing factors of airbag management belief comprised knowledge,department,and participation in specialized nurse or mechanical ventilation training.Primary influencing factors of airbag management behavior included knowledge,belief,department,participation in specialized nurse or mechanical ventilation training,and professional title.The belief in airbag management among ED nurses acted as a partial mediator between knowledge and behavior,with a total effect value of 0.513,and an indirect effect of 0.085,constituting 16.6%of the total effect.CONCLUSION ED nurses exhibit a positive attitude toward airbag management with relatively standardized practices,yet there remains room for improvement in their knowledge levels.Nursing managers should implement interventions tailored to the characteristics of ED nurses'airbag management knowledge,beliefs,and practices to enhance their airbag management proficiency.
基金the financial support of the National Natural Science Foundation of China(11972092,12002049,11802028)the Project of State Key Laboratory of Explosion Science and Technology(YBKT18-07,KFJJ19-12M).
文摘The compression behavior of the lattice-walled tubes under variable strain rates are investigated by numerical simulation,and the stress-strain relationship of the structure under quasi-static loading is theoretically analyzed.The finite element software LS-DYNA is used to simulate the structure established by the beam element,and the critical impact velocity is obtained when the structure collapses layer by layer.According to the plastic hinge theory and considering the combined action of the beam's bending moment and axial force in the structure,the stress-strain relationship of the structure under quasi-static loading is derived and compared with the experimental results.The numerical simulation results reveal that the structure of the single-layer gradient tube(SGC)does not undergo shear deformation under quasi-static and low-speed impact.The critical speed of the gradient square tube(GS)is higher than that of a cylindrical tube.The theoretical model can correctly reflect the mechanical response of the structure under uniaxial compression.
基金financially supported by the National Natural Science Foundation of China (Nos.22105116, 51872030,51631001,51702016,51902023 and 21801015)the Joint R&D Plan of Hong Kong,Macao,Taiwan and Beijing (No. Z191100001619002)+1 种基金the Fundamental Research Funds for the Central Universities (No.2017CX01003)Beijing Institute of Technology Research Fund Program for Young Scholars
文摘The synthesis of colloidal telluride semiconductor nanocrystals(CT-SNCs)is more challenging than that of chalcogenides,due to the smaller electron affinity of tellurium than that of sulfur and selenium,which is attributed to its metalloid property.While some new potential strategies were developing with the increasing demand of CT-SNCs,the cation exchange reaction(CER)has particularly become a new strategy to synthesize highquality CT-SNCs and their corresponded hetero-nanostructures.This review summarizes the synthesis strategies of CT-SNCs,including traditional methods and new methods with emphasis on CERs,and their resulting CTSNCs with well-controlling size,shape,composition,crystallization and hetero-interfaces cooperatively.The progressive synthesis methods give rise to the excellent optical properties of CT-SNCs.This review also covers the recent progress of their applications in the field of photoelectric detection,catalysis,batteries and biology.The new hybrid CT-SNCs nanostructures are also emphasized and systematically discussed due to their enhanced properties.
基金the National Natural Science Foundation of China(No.21174042)Fund of Project on the Integration of Industry,Education and Research of Guangdong Province(No.2013B090500072)
文摘A diquinoxalinopyrene （DQP） derivative and the corresponding oligomers （PDQPs） with Mn of ca. 3300, 4200, 5600, and 7300 have been synthesized. It is found that the band gaps and highest occupied molecular orbital （HOMO）/lowest unoccupied molecular orbital （LUMO） levels between DQP and its homopolymers only have a slight difference, implying a limited conjugation extension achieved from unimer to heptamer. The DFT calculation is in accordance with the experimental results. It reveals that the nodal planes are across the 2,11-positions in the LUMO and/or HOMO of DQP, dimer and trimer, which can be used to explain this special phenomenon.
