期刊文献+
共找到5,078篇文章
< 1 2 250 >
每页显示 20 50 100
European legal framework related to underground mining and tunnelling concerning commission directive (EU) 2017/164, 31 January establishing a fourth list of indicative occupational exposure limit values
1
作者 Miguel Tato Diogo 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2020年第4期541-545,共5页
Directive(EU)2017/164 establishes a fourth list of indicative occupational exposure limit values(IOELVs)to protect workers from risks of exposure to hazardous chemicals.It states that in underground mining and tunnell... Directive(EU)2017/164 establishes a fourth list of indicative occupational exposure limit values(IOELVs)to protect workers from risks of exposure to hazardous chemicals.It states that in underground mining and tunnelling,Member States may benefit from a transitional period regarding IOELVs for nitrogen monoxide,nitrogen dioxide,and carbon monoxide,during which the existing established IOELVs may be applied.The European Advisory Committee on Health and Safety at Work questions the technical feasibility of the proposed IOELVs in underground mining(CO,NO and NO2)and tunnelling(NO and NO2).Challenges arise concerning the availability of measurement methodologies for compliance with proposed IOELVs(NO2)in underground mining and tunnelling environments. 展开更多
关键词 Nitrogen monoxide Nitrogen dioxide Carbon monoxide IOELVs European directive 2017/164 Underground mining TUNNELLING
下载PDF
The Effect of Educational Intervention regarding Advance Care Planning for Advance Directives
2
作者 Yae Takeshita Mika Ikeda +1 位作者 Sayaka Sone Michiko Moriyama 《Health》 2015年第8期934-945,共12页
This study aimed to examine the effects of empowerment and education intervention to promote Advance Care Planning (ACP) for residents in a highly aged and depopulated region. The study utilized a single-group pre- an... This study aimed to examine the effects of empowerment and education intervention to promote Advance Care Planning (ACP) for residents in a highly aged and depopulated region. The study utilized a single-group pre- and post-test design and was conducted in Osakikamijima, Hiroshima, Japan. The researchers and town officials together formed an ACP committee and created an intervention framework. An ACP workshop was held for the participants and a self-administered questionnaire was carried out before, immediately after, and 3 months after the workshop. A total of 125 residents participated in the workshop and 87 of them completed more than 80% of the questionnaire items, whose responses were analyzed as valid responses. The number of participants who completed the AD increased significantly three months after the workshop (p = 0.008). There was a slight increase in the frequency of consultation with the family, but no change was observed in terms of consultation with healthcare providers. The educational intervention in-creased the respondents’ awareness and knowledge of ACP but did not affect the autonomous decision-making process regarding end-of-life care. This strategic process of ACP empowered the residents’ awareness and attitude towards end-of-life care with an increased completion rate of AD. On the other hand, cognitive barriers remained toward communication and decision-making shared with healthcare providers. Insufficient consultation with family members also became evident. Therefore, a new intervention strategy which helps increase communication with healthcare providers needs to be formulated and guidelines for consultation with the family and others need to be prepared. 展开更多
关键词 END-OF-LIFE ADVANCE CARE Planning ADVANCE directiveS COMMUNITY EMPOWERMENT
下载PDF
Advance Directives in the Context of Uncertain Prognosis for Residents of Nursing Homes
3
作者 Beryl E. Cable-Williams Donna M. Donna M. Wilson Norah Keating 《Open Journal of Nursing》 2014年第4期321-329,共9页
This report documents the findings of a mixed-methods study focused on the advanced directives of 182 residents of three LTC facilities in southern Ontario, Canada. Although almost all had a completed advance directiv... This report documents the findings of a mixed-methods study focused on the advanced directives of 182 residents of three LTC facilities in southern Ontario, Canada. Although almost all had a completed advance directive within 3 months of death, most did not have a palliative designation or directive until a few days before they died. Each facility’s written Progress Notes revealed staff members usually sought additional confirmation of care preferences from residents’ substitute decision-makers within a few days of the death. It was thus common for advance directives to change from a more interventionist approach to the least interventionist approach near death. This change indicates that the meaning and significance of advance care planning and resulting advance directives must be considered in light of the processes and temporal factors involved in their completion and use within this distinct population. The relational nature of advance care planning and concern about ageism as a factor for withholding or withdrawing life support for LTC residents are considered as possible explanatory factors. These findings and their implications are described in relation to end-of-life care policies and practices in LTC facilities. 展开更多
关键词 ADVANCE CARE Planning ADVANCE directiveS PALLIATIVE CARE Nursing HOMES
下载PDF
Renewable Diesel Fuel from Processing of Vegetable Oil in Hydrotreatment Units: Theoretical Compliance with European Directive 2009/28/EC and Ongoing Projects in Spain
4
作者 Daniel Garraín Israel Herrera +2 位作者 Carmen Lago Yolanda Lechón Rosa Sáez 《Smart Grid and Renewable Energy》 2010年第2期70-73,共4页
Oil hydrotreating units in refineries are aimed at reducing the sulfur content of fuels to accomplish standard par-ticular specifications. However, this process is currently one of the best available technologies to p... Oil hydrotreating units in refineries are aimed at reducing the sulfur content of fuels to accomplish standard par-ticular specifications. However, this process is currently one of the best available technologies to produce biofuels from vegetable oil in a refinery. Vegetable oils can be processed or co-processed in these units if several adaptations are performed, so some properties could be improved in comparison with conventional fuel such as density and cetane number. This study highlights the theoretical greenhouse gases (GHG) emissions (using a life cycle assessment–LCA-approach) of a hydrotreated vegetable oil (HVO) from bibliographical data. Results were compared with other biofuel production processes, such as those obtained by transesterification of vegetable oil (FAME, fatty acid methyl ester). It has also been included the comparison with conventional fossil diesel as a benchmark in order to assess the theoretical compliance with GHG savings proposed in European Directive 2009/28/EC. Finally, ongoing projects and future perspectives in Spain are mentioned. 展开更多
关键词 Hydrotreated Vegetable Oil FATTY Acid Methyl ESTER GHG Emissions SAVINGS directive 2009/28/EC RENEWABLE Diesel Fuel
下载PDF
Superdirective Circular Arrays of Electric and Huygens Dipole Elements
5
作者 Richard W Ziokowski 《Electromagnetic Science》 2024年第1期38-62,共25页
Uniform circular arrays(UCAs)provide both omnidirectional(360°)and directive(sector)coverage of the azimuthal plane.Superdirective versions with unidirectional,high front-to-back ratio(FTBR)properties could provi... Uniform circular arrays(UCAs)provide both omnidirectional(360°)and directive(sector)coverage of the azimuthal plane.Superdirective versions with unidirectional,high front-to-back ratio(FTBR)properties could provide the radiated field char-acteristics being pursued for NextG wireless networks and their perceived applications.Typical UCA configurations–full,semi-circular,and sector–that radiate vertically-polarized(VP)fields and are composed of either omnidirectional electric dipole ele-ments or unidirectional Huygens dipole elements are analyzed first with conventional methods as reference cases.These omni-and uni-directional element configurations are then treated with several optimization techniques:the classic Rayleigh-quotient(RQ)method and its unidirectional-constrained version;the eigenbeam decomposition and synthesis(EBDS)technique used to design su-perdirective acoustic receiving arrays;and the Bessel-azimuthal multipole(BEAM)approach developed herein.Several arrays are identified as being superdirective with extremely high FTBR values.The performance characteristics of the arrays of unidirectional elements are demonstrated to be superior in general.Moreover,it is shown that larger radius arrays with RQ-specified excitation amplitudes are robust to changes in them whereas the outcomes of the corresponding small radius versions are not.On the other hand,the BEAM-optimized densely-packed small-radius superdirective arrays are quite tolerant to those variations while generating unidirectional pseudo-needle beams. 展开更多
关键词 DIRECTIVITY Huygens dipole antennas MULTIPOLES Needle radiation Optimization Superdirective arrays Uniform circular arrays.
原文传递
ENTIRE SOLUTIONS OF HIGHER ORDER DIFFERENTIAL EQUATIONS WITH ENTIRE COEFFICIENTS HAVING THE SAME ORDER
6
作者 冯子恒 黄志波 李叶舟 《Acta Mathematica Scientia》 SCIE CSCD 2024年第1期355-368,共14页
In this paper,we consider entire solutions of higher order homogeneous differential equations with the entire coefficients having the same order,and prove that the entire solutions are of infinite lower order.The prop... In this paper,we consider entire solutions of higher order homogeneous differential equations with the entire coefficients having the same order,and prove that the entire solutions are of infinite lower order.The properties on the radial distribution,the limit direction of the Julia set and the existence of a Baker wandering domain of the entire solutions are also discussed. 展开更多
关键词 entire solutions radial order Julia limiting direction Baker wandering domain transcendental direction
下载PDF
临床药师参与1例心力衰竭、心肌梗死合并房颤患者的药物治疗
7
作者 受国徽 苏会源 李波霞 《海峡药学》 2024年第3期95-98,共4页
目的梳理复杂治疗方案后的抗栓方案,重整抗栓药物和疗程,纠正不合理用药,促进合理用药。方法临床药师介入1例心力衰竭、多次因心肌梗死植入多枚支架,合并房颤,行射频消融和左心耳封堵患者的药物治疗,重整抗栓药物方案,并全程监控治疗药... 目的梳理复杂治疗方案后的抗栓方案,重整抗栓药物和疗程,纠正不合理用药,促进合理用药。方法临床药师介入1例心力衰竭、多次因心肌梗死植入多枚支架,合并房颤,行射频消融和左心耳封堵患者的药物治疗,重整抗栓药物方案,并全程监控治疗药物,就不合理用药提出警示。结果患者明显好转,住院及出院随访期间未发生不良事件。结论临床药师的参与有助于精细化管理患者的药物治疗方案,并及时纠正不合理用药,更好的为患者服务。 展开更多
关键词 心力衰竭 心肌梗死 PCI支架植入术 直接口服抗凝药物(DOAC Direct oral anticoagulants) 利伐沙班 新活素(注射用重组人脑利钠肽) 沙库巴曲缬沙坦
下载PDF
Ascertaining the influences of auxiliary qubits on the Einstein–Podolsky–Rosen steering and its directions
8
作者 邢玲玲 杨欢 +1 位作者 张刚 孔敏 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第5期213-221,共9页
Einstein–Podolsky–Rosen(EPR) steering is an example of nontrivial quantum nonlocality and characteristic in the non-classical world.The directivity(or asymmetry) is a fascinating trait of EPR steering,and it is diff... Einstein–Podolsky–Rosen(EPR) steering is an example of nontrivial quantum nonlocality and characteristic in the non-classical world.The directivity(or asymmetry) is a fascinating trait of EPR steering,and it is different from other quantum nonlocalities.Here,we consider the strategy in which two atoms compose a two-qubit X state,and the two atoms are owned by Alice and Bob,respectively.The atom of Alice suffers from a reservoir,and the atom of Bob couples with a bit flip channel.The influences of auxiliary qubits on EPR steering and its directions are revealed by means of the entropy uncertainty relation.The results indicate that EPR steering declines with growing time t when adding fewer auxiliary qubits.The EPR steering behaves as damped oscillation when introducing more auxiliary qubits in the strong coupling regime.In the weak coupling regime,the EPR steering monotonously decreases as t increases when coupling auxiliary qubits.The increases in auxiliary qubits are responsible for the fact that the steerability from Alice to Bob(or from Bob to Alice) can be more effectively revealed.Notably,the introductions of more auxiliary qubits can change the situation that steerability from Alice to Bob is certain to a situation in which steerability from Bob to Alice is certain. 展开更多
关键词 auxiliary qubits EPR steering DIRECTIONS influence
下载PDF
Preventing brain aging by the artificial enforcement of the unfolded protein response:future directions
9
作者 Felipe Cabral-Miranda Claudio Hetz 《Neural Regeneration Research》 SCIE CAS CSCD 2024年第2期393-394,共2页
As the life expectancy of the world’s population increases,age-related diseases are emerging as one of the greatest problems facing modern society.The onset of dementia and neurodegenerative diseases is strictly depe... As the life expectancy of the world’s population increases,age-related diseases are emerging as one of the greatest problems facing modern society.The onset of dementia and neurodegenerative diseases is strictly dependent on aging as a major risk factor and has a profound impact on various aspects of the lives of individuals and their families. 展开更多
关键词 DISEASES AGING DIRECTIONS
下载PDF
Effect of titanium on the sticking of pellets based on hydrogen metallurgy shaft furnace:Behavior analysis and mechanism evolution
10
作者 Jinge Feng Jue Tang +4 位作者 Zichuan Zhao Mansheng Chu Aijun Zheng Xiaobing Li Xiao’ai Wang 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2024年第2期282-291,共10页
Direct reduction based on hydrogen metallurgical gas-based shaft furnace is a promising technology for the efficient and low-carbon smelting of vanadium-titanium magnetite.However,in this process,the sticking of pelle... Direct reduction based on hydrogen metallurgical gas-based shaft furnace is a promising technology for the efficient and low-carbon smelting of vanadium-titanium magnetite.However,in this process,the sticking of pellets occurs due to the aggregation of metal-lic iron between the contact surfaces of adjacent pellets and has a serious negative effect on the continuous operation.This paper presents a detailed experimental study of the effect of TiO2 on the sticking behavior of pellets during direct reduction under different conditions.Results showed that the sticking index(SI)decreased linearly with the increasing TiO2 addition.This phenomenon can be attributed to the increase in unreduced FeTiO3 during reduction,leading to a decrease in the number and strength of metallic iron interconnections at the sticking interface.When the TiO2 addition amount was raised from 0 to 15wt%at 1100°C,the SI also increased from 0.71%to 59.91%.The connection of the slag phase could be attributed to the sticking at a low reduction temperature,corresponding to the low sticking strength.Moreover,the interconnection of metallic iron became the dominant factor,and the SI increased sharply with the increase in re-duction temperature.TiO2 had a greater effect on SI at a high reduction temperature than at a low reduction temperature. 展开更多
关键词 TITANIUM sticking index hydrogen metallurgy direct reduction PELLETS
下载PDF
Profiling Electronic and Phononic Band Structures of Semiconductors at Finite Temperatures: Methods and Applications
11
作者 张燮 康俊 魏苏淮 《Chinese Physics Letters》 SCIE EI CAS CSCD 2024年第2期57-68,共12页
Semiconductor devices are often operated at elevated temperatures that are well above zero Kelvin,which is the temperature in most first-principles density functional calculations.Computational approaches to com-putin... Semiconductor devices are often operated at elevated temperatures that are well above zero Kelvin,which is the temperature in most first-principles density functional calculations.Computational approaches to com-puting and understanding the properties of semiconductors at finite temperatures are thus in critical demand.In this review,we discuss the recent progress in computationally assessing the electronic and phononic band structures of semiconductors at finite temperatures.As an emerging semiconductor with particularly strong temperature-induced renormalization of the electronic and phononic band structures,halide perovskites are used as a representative example to demonstrate how computational advances may help to understand the band struc-tures at elevated temperatures.Finally,we briefly illustrate the remaining computational challenges and outlook promising research directions that may help to guide future research in this field. 展开更多
关键词 FINITE struc DIRECTIONS
下载PDF
Anisotropic Band Evolution of Bulk Black Phosphorus Induced by Uniaxial Tensile Strain
12
作者 邓亚丰 张艺琳 +7 位作者 赵亚飞 徐永康 代兴泽 王双海 陆显扬 黎遥 徐永兵 何亮 《Chinese Physics Letters》 SCIE EI CAS CSCD 2024年第3期83-96,共14页
We investigate the anisotropic band structure and its evolution under tensile strains along different crystallographic directions in bulk black phosphorus(BP)using angle-resolved photoemission spectroscopy and density... We investigate the anisotropic band structure and its evolution under tensile strains along different crystallographic directions in bulk black phosphorus(BP)using angle-resolved photoemission spectroscopy and density functional theory.The results show that there are band crossings in the Z-L(armchair)direction. 展开更多
关键词 DIRECTIONS BULK PHOSPHORUS
下载PDF
Across two phylogeographic breaks: Quaternary evolutionary history of a mountain aspen (Populus rotundifolia) in the Hengduan Mountains
13
作者 Jieshi Tang Xiaoyan Fan +6 位作者 Richard I.Milne Heng Yang Wenjing Tao Xinran Zhang Mengyun Guo Jialiang Li Kangshan Mao 《Plant Diversity》 SCIE CAS CSCD 2024年第3期321-332,共12页
Biogeographical barriers to gene flow are central to plant phylogeography.In East Asia,plant distribution is greatly influenced by two phylogeographic breaks,the Mekong-Salween Divide and Tanaka-Kaiyong Line,however,f... Biogeographical barriers to gene flow are central to plant phylogeography.In East Asia,plant distribution is greatly influenced by two phylogeographic breaks,the Mekong-Salween Divide and Tanaka-Kaiyong Line,however,few studies have investigated how these barriers affect the genetic diversity of species that are distributed across both.Here we used 14 microsatellite loci and four chloroplast DNA fragments to examine genetic diversity and distribution patterns of 49 populations of Populus rotundifolia,a species that spans both the Mekong-Salween Divide and the Tanaka-Kaiyong Line in southwestern China.Demographic and migration hypotheses were tested using coalescent-based approaches.Limited historical gene flow was observed between the western and eastern groups of P.rotundifolia,but substantial flow occurred across both the Mekong-Salween Divide and Tanaka-Kaiyong Line,manifesting in clear admixture and high genetic diversity in the central group.Wind-borne pollen and seeds may have facilitated the dispersal of P.rotundifolia following prevalent northwest winds in the spring.We also found that the Hengduan Mountains,where multiple genetic barriers were detected,acted on the whole as a barrier between the western and eastern groups of P.rotundifolia.Ecological niche modeling suggested that P.rotundifolia has undergone range expansion since the last glacial maximum,and demographic reconstruction indicated an earlier population expansion around 600 Ka.The phylogeographic pattern of P.rotundifolia reflects the interplay of biological traits,wind patterns,barriers,niche differentiation,and Quaternary climate history.This study emphasizes the need for multiple lines of evidence in understanding the Quaternary evolution of plants in topographically complex areas. 展开更多
关键词 Chloroplast DNA MICROSATELLITE Phylogeographic break Populus rotundifolia Quaternary history Wind direction
下载PDF
Progress,challenges,and prospects of spent lithium-ion batteries recycling:A review
14
作者 Pengwei Li Shaohua Luo +7 位作者 Lin Zhang Qiuyue Liu Yikai Wang Yicheng Lin Can Xu Jia Guo Peam Cheali Xiaoning Xia 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第2期144-171,I0005,共29页
The recycling and reutilization of spent lithium-ion batteries(LIBs)have become an important measure to alleviate problems like resource scarcity and environmental pollution.Although some progress has been made,batter... The recycling and reutilization of spent lithium-ion batteries(LIBs)have become an important measure to alleviate problems like resource scarcity and environmental pollution.Although some progress has been made,battery recycling technology still faces challenges in terms of efficiency,effectiveness and environmental sustainability.This review aims to systematically review and analyze the current status of spent LIB recycling,and conduct a detailed comparison and evaluation of different recycling processes.In addition,this review introduces emerging recycling techniques,including deep eutectic solvents,molten salt roasting,and direct regeneration,with the intent of enhancing recycling efficiency and diminishing environmental repercussions.Furthermore,to increase the added value of recycled materials,this review proposes the concept of upgrading recycled materials into high value-added functional materials,such as catalysts,adsorbents,and graphene.Through life cycle assessment,the paper also explores the economic and environmental impacts of current battery recycling and highlights the importance that future recycling technologies should achieve a balance between recycling efficiency,economics and environmental benefits.Finally,this review outlines the opportunities and challenges of recycling key materials for next-generation batteries,and proposes relevant policy recommendations to promote the green and sustainable development of batteries,circular economy,and ecological civilization. 展开更多
关键词 Spent li-ion batteries RECYCLE Direct regeneration High-value conversion Functional materials
下载PDF
Stability assessment of tree ring growth of Pinus armandii Franch in response to climate change based on slope directions at the Lubanling in the Funiu Mountains,China
15
作者 Jinkuan Li Jianfeng Peng +4 位作者 Xiaoxu Wei Meng Peng Xuan Li Yameng Liu Jiaxin Li 《Journal of Forestry Research》 SCIE EI CAS CSCD 2024年第2期197-208,共12页
Global warming will affect growth strategies and how trees will adapt.To compare the response of tree radial growth to climate warming in different slope directions,samples of Pinus armandii Franch were collected and ... Global warming will affect growth strategies and how trees will adapt.To compare the response of tree radial growth to climate warming in different slope directions,samples of Pinus armandii Franch were collected and treering chronologies developed on northern and western slopes from the Lubanling in the Funiu Mountains.Correlation analyses showed that two chronologies were mainly limited by temperatures in the previous June–August and the combination of temperatures and moisture in the current May–July.The difference of the climate response to slopes was small but not negligible.Radial growth of the LBL01 site on the northern slope was affected by the combined maximum and minimum temperatures,while that of the LBL02 site was affected by maximum temperatures.With regards to moisture,radial growth of the trees on the north slope was influenced by the relative humidity in the current May–July,while on the western slope,it was affected by the relative humidity in the previous June–August,the current May–July and the precipitation in the current May–July.With the change in climate,the effects of the main limiting factors on growth on different slopes were visible to a certain extent,but the differences in response of trees on different slopes gradually decreased,which might be caused by factors such as different slope directions and the change in diurnal temperature range.These results may provide information for forest protection and ecological construction in this region,and a scientific reference for future climate reconstruction. 展开更多
关键词 Tree ring width Lubanling Pinus armandii Franch Slope direction Climate response
下载PDF
Efficient Direct Decomposition of NO over La_(0.8)A_(0.2)NiO_(3)(A=K, Ba, Y) Catalysts under Microwave Irradiation
16
作者 王浩 ZHAO Zijian +1 位作者 DUAN Xinghui ZHOU Shijia 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2024年第1期17-23,共7页
La_(0.8)A_(0.2)NiO_(3) (A=K,Ba,Y) catalysts supported on the microwave-absorbing ceramic heating carrier were prepared by the sol-gel method.The crystalline phase and the catalytic activity of the La_(0.8)A_(0.2)NiO_(... La_(0.8)A_(0.2)NiO_(3) (A=K,Ba,Y) catalysts supported on the microwave-absorbing ceramic heating carrier were prepared by the sol-gel method.The crystalline phase and the catalytic activity of the La_(0.8)A_(0.2)NiO_(3)catalysts were characterized by XRD and H_(2) temperature-programmed reduction (TPR).The effects of reaction temperature,oxygen concentration,and gas flow rate on the direct decomposition of nitric oxide over the synthesized catalysts were studied under microwave irradiation (2.45 GHz).The XRD results indicated that the La_(0.8)A_(0.2)NiO_(3) catalysts formed an ABO_(3) perovskite structure,and the H_(2)-TPR results revealed that the relative reducibility of the catalysts increased in the order of La_(0.8)K_(0.2)NiO_(3)>La_(0.8)Ba_(0.2)NiO_(3)>La_(0.8)Y_(0.2)Ni O_(3).Under microwave irradiation,the highest NO conversion amounted to 98.9%,which was obtained with the La_(0.8)K_(0.2)NiO_(3) catalyst at 400℃.The oxygen concentration did not inhibit the NO decomposition on the La_(0.8)A_(0.2)NiO_(3) catalysts,thus the N_(2) selectivity exceeded 99.8%under excess oxygen at 550℃.The NOconversion of the La_(0.8)A_(0.2)NiO_(3) catalysts decreased linearly with the increase in the gas flow rate. 展开更多
关键词 microwave catalysis direct decomposition of NO microwave-absorbing heating ceramics perovskite catalyst
下载PDF
Engineering Nano/Microscale Chiral Self‑Assembly in 3D Printed Constructs
17
作者 Mohsen Esmaeili Ehsan Akbari +3 位作者 Kyle George Gelareh Rezvan Nader Taheri‑Qazvini Monirosadat Sadati 《Nano-Micro Letters》 SCIE EI CSCD 2024年第3期313-332,共20页
Helical hierarchy found in biomolecules like cellulose,chitin,and collagen underpins the remarkable mechanical strength and vibrant colors observed in living organisms.This study advances the integration of helical/ch... Helical hierarchy found in biomolecules like cellulose,chitin,and collagen underpins the remarkable mechanical strength and vibrant colors observed in living organisms.This study advances the integration of helical/chiral assembly and 3D printing technology,providing precise spatial control over chiral nano/microstructures of rod-shaped colloidal nanoparticles in intricate geometries.We designed reactive chiral inks based on cellulose nanocrystal(CNC)suspensions and acrylamide monomers,enabling the chiral assembly at nano/microscale,beyond the resolution seen in printed materials.We employed a range of complementary techniques including Orthogonal Superposition rheometry and in situ rheo-optic measurements under steady shear rate conditions.These techniques help us to understand the nature of the nonlinear flow behavior of the chiral inks,and directly probe the flow-induced microstructural dynamics and phase transitions at constant shear rates,as well as their post-flow relaxation.Furthermore,we analyzed the photo-curing process to identify key parameters affecting gelation kinetics and structural integrity of the printed object within the supporting bath.These insights into the interplay between the chiral inks self-assembly dynamics,3D printing flow kinematics and photopolymerization kinetics provide a roadmap to direct the out-of-equilibrium arrangement of CNC particles in the 3D printed filaments,ranging from uniform nematic to 3D concentric chiral structures with controlled pitch length,as well as random orientation of chiral domains.Our biomimetic approach can pave the way for the creation of materials with superior mechanical properties or programable photonic responses that arise from 3D nano/microstructure and can be translated into larger scale 3D printed designs. 展开更多
关键词 Directed chiral self-assembly Cellulose nanocrystals Bioinspired nanocomposite 3D printing RHEOLOGY
下载PDF
Effect of hot isostatic pressure on the microstructure and tensile properties of γ'-strengthened superalloy fabricated through induction-assisted directed energy deposition
18
作者 Jianjun Xu Hanlin Ding +1 位作者 Xin Lin Feng Liu 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2024年第5期1089-1097,共9页
The microstructure characteristics and strengthening mechanism of Inconel738LC(IN-738LC) alloy prepared by using induction-assisted directed energy deposition(IDED) were elucidated through the investigation of samples... The microstructure characteristics and strengthening mechanism of Inconel738LC(IN-738LC) alloy prepared by using induction-assisted directed energy deposition(IDED) were elucidated through the investigation of samples subjected to IDED under 1050℃ preheating with and without hot isostatic pressing(HIP,1190℃,105 MPa,and 3 h).Results show that the as-deposited sample mainly consisted of epitaxial columnar crystals and inhomogeneously distributed γ’ phases in interdendritic and dendritic core regions.After HIP,grain morphology changed negligibly,whereas the size of the γ’ phase became increasingly even.After further heat treatment(HT,1070℃,2 h + 845℃,24 h),the γ’ phase in the as-deposited and HIPed samples presented a bimodal size distribution,whereas that in the as-deposited sample showed a size that remained uneven.The comparison of tensile properties revealed that the tensile strength and uniform elongation of the HIP + HTed sample increased by 5% and 46%,respectively,due to the synergistic deformation of bimodal γ’phases,especially large cubic γ’ phases.Finally,the relationship between phase transformations and plastic deformations in the IDEDed sample was discussed on the basis of generalized stability theory in terms of the trade-off between thermodynamics and kinetics. 展开更多
关键词 directed energy deposition Ni-based superalloys high-temperature preheating hot isostatic pressing MICROSTRUCTURE tensile properties
下载PDF
Estimation of the anisotropy of hydraulic conductivity through 3D fracture networks using the directional geological entropy
19
作者 Chuangbing Zhou Zuyang Ye +2 位作者 Chi Yao Xincheng Fan Feng Xiong 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2024年第2期137-148,共12页
With an extension of the geological entropy concept in porous media,the approach called directional entrogram is applied to link hydraulic behavior to the anisotropy of the 3D fracture networks.A metric called directi... With an extension of the geological entropy concept in porous media,the approach called directional entrogram is applied to link hydraulic behavior to the anisotropy of the 3D fracture networks.A metric called directional entropic scale is used to measure the anisotropy of spatial order in different directions.Compared with the traditional connectivity indexes based on the statistics of fracture geometry,the directional entropic scale is capable to quantify the anisotropy of connectivity and hydraulic conductivity in heterogeneous 3D fracture networks.According to the numerical analysis of directional entrogram and fluid flow in a number of the 3D fracture networks,the hydraulic conductivities and entropic scales in different directions both increase with spatial order(i.e.,trace length decreasing and spacing increasing)and are independent of the dip angle.As a result,the nonlinear correlation between the hydraulic conductivities and entropic scales from different directions can be unified as quadratic polynomial function,which can shed light on the anisotropic effect of spatial order and global entropy on the heterogeneous hydraulic behaviors. 展开更多
关键词 3D fracture network Geological entropy Directional entropic scale ANISOTROPY Hydraulic conductivity
下载PDF
Post-transcriptional mechanisms controlling neurogenesis and direct neuronal reprogramming
20
作者 Elsa Papadimitriou Dimitra Thomaidou 《Neural Regeneration Research》 SCIE CAS CSCD 2024年第9期1929-1939,共11页
Neurogenesis is a tightly regulated process in time and space both in the developing embryo and in adult neurogenic niches.A drastic change in the transcriptome and proteome of radial glial cells or neural stem cells ... Neurogenesis is a tightly regulated process in time and space both in the developing embryo and in adult neurogenic niches.A drastic change in the transcriptome and proteome of radial glial cells or neural stem cells towards the neuronal state is achieved due to sophisticated mechanisms of epigenetic,transcriptional,and post-transcriptional regulation.Understanding these neurogenic mechanisms is of major importance,not only for shedding light on very complex and crucial developmental processes,but also for the identification of putative reprogramming factors,that harbor hierarchically central regulatory roles in the course of neurogenesis and bare thus the capacity to drive direct reprogramming towards the neuronal fate.The major transcriptional programs that orchestrate the neurogenic process have been the focus of research for many years and key neurogenic transcription factors,as well as repressor complexes,have been identified and employed in direct reprogramming protocols to convert non-neuronal cells,into functional neurons.The post-transcriptional regulation of gene expression during nervous system development has emerged as another important and intricate regulatory layer,strongly contributing to the complexity of the mechanisms controlling neurogenesis and neuronal function.In particular,recent advances are highlighting the importance of specific RNA binding proteins that control major steps of mRNA life cycle during neurogenesis,such as alternative splicing,polyadenylation,stability,and translation.Apart from the RNA binding proteins,microRNAs,a class of small non-coding RNAs that block the translation of their target mRNAs,have also been shown to play crucial roles in all the stages of the neurogenic process,from neural stem/progenitor cell proliferation,neuronal differentiation and migration,to functional maturation.Here,we provide an overview of the most prominent post-transcriptional mechanisms mediated by RNA binding proteins and microRNAs during the neurogenic process,giving particular emphasis on the interplay of specific RNA binding proteins with neurogenic microRNAs.Taking under consideration that the molecular mechanisms of neurogenesis exert high similarity to the ones driving direct neuronal reprogramming,we also discuss the current advances in in vitro and in vivo direct neuronal reprogramming approaches that have employed microRNAs or RNA binding proteins as reprogramming factors,highlighting the so far known mechanisms of their reprogramming action. 展开更多
关键词 direct neuronal reprogramming in vivo glia-to-neuron conversion microRNAs NEUROGENESIS post-transcriptional regulation RNA binding proteins
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部