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2D/2D atomic double-layer WS_(2)/Nb_(2)O_(5)shell/core nanosheets with ultrafast interfacial charge transfer for boosting photocatalytic H_(2)evolution 被引量:2
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作者 Bo Lin Hao Chen +12 位作者 Yao Zhou Xiao Luo Dan Tian Xiaoqing Yan Ruihuan Duan Jun Di Lixing Kang Aimin Zhou Guidong Yang Yonghui Li Jiadong Zhou Zheng Liu Fucai Liu 《Chinese Chemical Letters》 SCIE CAS CSCD 2021年第10期3128-3132,共5页
Low-efficiency charge transfer is a critical factor to limit the photocatalytic H_(2)evolution activity of semiconductor photocatalysts.The interface design is a promising approach to achieve high chargetransfer effic... Low-efficiency charge transfer is a critical factor to limit the photocatalytic H_(2)evolution activity of semiconductor photocatalysts.The interface design is a promising approach to achieve high chargetransfer efficiency for photocatalysts.Herein,a new 2 D/2 D atomic double-layer WS_(2)/Nb_(2)O_(5)shell/core photocatalyst(DLWS/Nb_(2)O_(5))is designed.The atom-resolved HAADF-STEM results unravel the presence of an unusual 2 D/2 D shell/core interface in DLWS/Nb_(2)O_(5).Taking advantage of the advanced femtosecond-resolved ultrafast TAS spectra,the average lifetime of charge carriers for DLWS/Nb_(2)O_(5)(180.97 ps)is considerably shortened as compared to that of Nb_(2)O_(5)(230.50 ps),strongly indicating that the 2 D/2 D shell/core interface enables DLWS/Nb_(2)O_(5)to achieve ultrafast charge transfer from Nb_(2)O_(5)to atomic double-layer WS_(2),thus yielding a high photocatalytic H_(2)evolution rate of 237.6 mmol/h,up to10.8 times higher than that of pure Nb_(2)O_(5)nanosheet.This study will open a new window for the development of high-efficient photocatalytic systems through the interface design. 展开更多
关键词 2D/2D shell/core interface atomic double-layer WS_(2) Nb_(2)O_(5)nanosheet Charge transfer Photocatalytic H_(2)evolution
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Cobalt and nitrogen atoms co-doped porous carbon for advanced electrical double-layer capacitors 被引量:2
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作者 Aiqin Xiang Shuai Xie +5 位作者 Fei Pan Hongchang Jin Yiheng Zhai Yanwu Zhu Xianghua Kong Hengxing Ji 《Chinese Chemical Letters》 SCIE CAS CSCD 2021年第2期830-833,共4页
Electrical double-layer capacitors are widely concerned for their high power density,long cycling life and high cycling efficiency.However,their wide application is limited by their low energy density.In this study,we... Electrical double-layer capacitors are widely concerned for their high power density,long cycling life and high cycling efficiency.However,their wide application is limited by their low energy density.In this study,we propose a simple yet environmental friendly method to synthesize cobalt and nitrogen atoms co-doped porous carbon(CoAT-NC) material.Cobalt atoms connected with primarily pyridinic nitrogen atoms can be uniformly dispersed in the amorphous carbon matrix,which is benefit for improving electrical conductivity and density of states of the carbon material.Therefore,an enhanced perfo rmance is expected when CoAT-NC is served as electrode in a supercapacitor device.CoAT-NC displays a good gravimetric capacitance of 160 F/g at 0.5 A/g combing with outstanding capacitance retention of 90% at an extremely high current density of 100 A/g in acid electrolyte.Furthermore,a good energy density of 30 Wh/kg can be obtained in the organic electrolyte. 展开更多
关键词 Electrical double-layer capacitors Cobalt atoms Pyridinic nitrogen CO-DOPED Density of states
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Superconductivity and band topology of double-layer honeycomb structure M_(2)N_(2)(M=Nb,Ta)
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作者 Jin-Han Tan Na Jiao +2 位作者 Meng-Meng Zheng Ping Zhang Hong-Yan Lu 《Chinese Physics B》 2025年第9期581-587,共7页
Two-dimensional double-layer honeycomb(DLHC)materials are known for their diverse physical properties,but superconductivity has been a notably absent characteristic in this structure.We address this gap by investigati... Two-dimensional double-layer honeycomb(DLHC)materials are known for their diverse physical properties,but superconductivity has been a notably absent characteristic in this structure.We address this gap by investigating M_(2)N_(2)(M=Nb,Ta)with DLHC structure using first-principles calculations.Our results show that M_(2)N_(2)are stable and metallic,exhibiting superconducting behavior.Specifically,Nb_(2)N_(2)and Ta_(2)N_(2)display superconducting transition temperatures of 6.8 K and 8.8 K,respectively.Their electron-phonon coupling is predominantly driven by the coupling between metal d-orbitals and low-frequency metal-dominated vibration modes.Interestingly,two compounds also exhibit non-trivial band topology.Thus,M_(2)N_(2)are promising platforms for studying the interplay between topology and superconductivity and fill the gap in superconductivity research for DLHC materials. 展开更多
关键词 first-principles calculations phonon-mediated superconductivity double-layer honeycomb structure band topology
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Atomic density disturbance rejection in atomic gyroscopes via faraday polarimetric decoupling
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作者 Zehua Liu Yifan Yan +5 位作者 Haoying Pang Xinhui Liu Jixi Lu Xusheng Lei Zhuo Wang Wei Quan 《Defence Technology(防务技术)》 2026年第1期1-10,共10页
Atomic spin gyroscopes are promising candidates for next-generation inertial navigation due to extremely high theoretical precision,relatively small size among atomic gyroscopes,and promising potential for miniaturiza... Atomic spin gyroscopes are promising candidates for next-generation inertial navigation due to extremely high theoretical precision,relatively small size among atomic gyroscopes,and promising potential for miniaturization.In particular,the spin-exchange relaxation-free(SERF)atomic gyroscope relies on optical pumping to polarize atoms,enabling rotation sensing through the Faraday optical rotation angle(FORA).However,fluctuations in atomic density introduce systematic errors in FORA measurements,limiting long-term stability.We present a data-driven decoupling method that isolates atomic density fluctuations from the FORA signal by modeling spatially resolved light absorption in the vapor cell.The model accounts for the spatial distribution of spin polarization in the pump-light interaction volume,density-dependent relaxation rates,wall-induced relaxation,and polarization diffusion,and is implemented within a finite-element framework.Compared to the conventional Lambert-Beer law,which assumes one-dimensional homogeneity,our approach captures the full threedimensional density and polarization distribution,significantly improving the accuracy of light absorption modeling.The resulting absorption-density maps are used to train a feedforward neural network,yielding a high-precision estimator for atomic density fluctuations.This estimator enables the construction of a decoupling equation that separates the density contribution from the FORA signal.Experimental validation shows that this method improves the bias instability atσ(100 s)of the gyroscope was improved by 73.1%compared to traditional platinum-resistance-based stabilization.The proposed framework is general and can be extended to other optical pumping-based sensors,such as optically pumped magnetometers. 展开更多
关键词 atomic gyroscope SERF gyroscope atomic density Optically pumped sensors
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Atomically Dispersed Pt-Ru Dual-Atom Catalysts for Efficient Low-Temperature CO Oxidation Reaction
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作者 Yanan Qi Hongqiu Chen +12 位作者 Feng Hong Xiangbin Cai Zhehan Ying Jiangyong Diao Zhimin Jia Jiawei Chen Ning Wang Shengling Xiang Xiaowen Chen Guodong Wen Bo Sun Geng Sun Hongyang Liu 《Nano-Micro Letters》 2026年第5期816-830,共15页
Single-atom catalysts(SACs)have demonstrated excellent performance in heterogeneous catalytic reactions owing to their maximized atomic efficiency,distinctive geometric,and electronic configurations.However,the effica... Single-atom catalysts(SACs)have demonstrated excellent performance in heterogeneous catalytic reactions owing to their maximized atomic efficiency,distinctive geometric,and electronic configurations.However,the efficacy of SACs remains limited for certain reactions requiring simultaneous activation of multiple reactants over metallic active sites.Herein,we report an atomically dispersed Pt1Ru1 dual-atom pair site anchored on nanodiamond@graphene(ND@G)for CO oxidation.The Pt1Ru1 dual-atom catalyst shows an exceptional turnover frequency(TOF)of 17.6.10^(-2)s^(-1)at significantly lower temperature(30℃),achieving a tenfold increase in TOF compared to singleatom Pt1/ND@G catalyst(1.5.10^(-2)s^(-1))and surpassing to previously reported Pt-based catalysts under similar conditions.Moreover,the catalyst demonstrates excellent stability,maintaining its activity for 40 h at 80℃without significant deactivation.The superior catalytic performance of Pt-Ru dual-atom catalysts is attributed to the synergistic effect between Pt and Ru atoms with enhanced metallicity for improving simultaneous adsorption and activation of CO and O_(2),and the tuning of conventional competitive reactant adsorption into a non-competitive pathway over dual-atom pair sites.The present work manifests the advantages of dual-atom pair sites in heterogeneous catalysis and paves the way for precise design of catalysts at the atomic scale. 展开更多
关键词 CO oxidation atomically dispersed Dual-atom catalysts Pt-Ru Synergistic effect
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Photocatalytic carboxylation of alkenes via synergistic hydrogen-atom transfer and proton transfer
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作者 Senmao Zhai Hao Hou +2 位作者 Liwei Wang Xiaotian Qi Meifang Zheng 《Science China Chemistry》 2026年第2期807-812,共6页
A visible-light-induced synergistic hydrogen atom transfer(HAT)and proton transfer(PT)catalysis was developed for the defluorinative carboxylation of α-CF_(2)R-substituted alkenes.This system affords a variety of γ,... A visible-light-induced synergistic hydrogen atom transfer(HAT)and proton transfer(PT)catalysis was developed for the defluorinative carboxylation of α-CF_(2)R-substituted alkenes.This system affords a variety of γ,γ-difluoro-and γ-monofluoro-vinylacetic acids without stepwise acidification,exhibiting good functional group tolerance,broad scope,and facile scalability.Mechanism studies support that thiol plays the role of the hydrogen relay,which s a hydrogen atom through HAT and then outputs a proton via PT.This strategy also takes full advantage of formate for photocatalytic carboxylation reaction in a step-and atomeconomical way. 展开更多
关键词 photoredox catalysis CARBOXYLATION hydrogen atom transfer proton transfer
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Rational design of atomic skin layers with low Ir-Ir atomic distance for highly efficient OER catalysts
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作者 Zhen Zeng Yuling Hu +6 位作者 Yun Liu Hao Zhang Wenjuan Shi Zhenye Kang Yuliang Yuan Wei Sun Xinlong Tian 《Science China Materials》 2026年第3期1448-1455,共8页
The development of catalysts with highly efficient oxygen evolution performance and low-Ir loading is key to scaling up the application of proton exchange membrane(PEM)water electrolysis technology.Here,an Ir-skin cat... The development of catalysts with highly efficient oxygen evolution performance and low-Ir loading is key to scaling up the application of proton exchange membrane(PEM)water electrolysis technology.Here,an Ir-skin catalyst(Ir@KM)is realized on a potassium-manganese oxide(K_(0.25)MnO_(x)(KM))using an ion-exchange method.The Ir-skin over the prepared Ir@KM has a low Ir-Ir atomic distance,endowing an energetically favorable oxide path mechanism to allow a low theoretical overpotential of 0.13 V.Ir@KM offers a low overpotential of~280 mV at a current density of 10 mA cm^(-2)and provides a high mass activity of up to 18,500 A at a cell voltage of 1.8 V in PEM,which is 17.6 times higher than that of IrO_(2),demonstrating a significant advantage in reducing the cost of the membrane electrode.The presented Ir-skin concept represents a promising strategy to fabricate low-Ir catalyst with high activity and durability for practical applications of PEM. 展开更多
关键词 OER Ir-based oxides skin catalyst low atomic distance PEM
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W/V Dual-Atom Doping MoS_(2)-Mediated Phase Transition for Efficient Polysulfide Adsorption/Conversion Kinetics in Lithium-Sulfur Battery
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作者 Zhe Cui Ping Feng +2 位作者 Gang Zhong Qingdong Ou Mingkai Liu 《Nano-Micro Letters》 2026年第4期700-717,共18页
The dissolvable polysulfides and sluggish Li_2S conversion kinetics are acknowledged as two significant challenges in the application lithium-sulfur(Li-S)batteries.Herein,we introduce a dual-doping strategy to modulat... The dissolvable polysulfides and sluggish Li_2S conversion kinetics are acknowledged as two significant challenges in the application lithium-sulfur(Li-S)batteries.Herein,we introduce a dual-doping strategy to modulate the electronic structure of MoS_(2),thereby obtaining a multifunctional catalyst that serves as an efficient sulfur host.The W/V dual single-atomdoped MoS_(2)grown on carbon nanofibers(CMWVS)demonstrates a strong adsorption ability for lithium polysulfides,suppressing the shuttle effects.Additionally,the doping process also results in the phase transition from 2H-MoS_(2)to 1T-MoS_(2)and generates sufficient edge sulfur atoms,promoting the charge/electron transfer and enriching the reaction sites.All these merits contribute to the superior conversion reaction kinetics,leading to the outstanding Li-S battery performance.When fabricated as cathodes by compositing with sulfur,the CMWVS/S cathode delivers a high capacity of 1481.7 mAh g^(-1)at 0.1 C(1 C=1672 mAh g^(-1))and maintains 816.3 m Ah g^(-1)after 1000 cycles at 1.0 C,indicating outstanding cycling stability.Even under a high sulfur loading of 7.9 mg cm^(-2)and lean electrolyte conditions(E/S ratio of 9.0μL mg^(-1)),the cathode achieves a high areal capacity of 8.2 m Ah cm^(-2),showing great promise for practical Li-S battery applications.This work broadens the scope of doping strategies in transition-metal dichalcogenides by tailoring their electronic structures,providing insightful direction for the rational development of high-efficiency electrocatalysts for advanced Li-S battery applications. 展开更多
关键词 lithium-sulfur batteries ELECTROCATALYST Phase transition Dual single atoms Molybdenum disulfide
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Chlorinated antibiotics electrocatalytic dechlorination by construction of Co_(3)O_(4)/g-C_(3)N_(4) heterojunctions for stable atomic hydrogen production
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作者 Ge Song Huizhong Wu +5 位作者 Chaohui Zhang Xuechun Wang Shuaishuai Li Jiangli Sun Xiuwu Zhang Minghua Zhou 《Chinese Chemical Letters》 2026年第2期713-720,共8页
Chlorinated antibiotics pose great challenges in efficient removal,while for the first time,this work greatly enhanced their electrocatalytic dechlorination performance by construction of non-noble metal Co_(3)O_(4)/g... Chlorinated antibiotics pose great challenges in efficient removal,while for the first time,this work greatly enhanced their electrocatalytic dechlorination performance by construction of non-noble metal Co_(3)O_(4)/g-C_(3)N_(4) heterojunctions to improve process cost-effectiveness.The Co_(3)O_(4)/g-C_(3)N_(4) heterojunction demonstrated an effective removal of 93.6%thiamphenicol(TAP)within 45 min,with the rate constant(0.0584 min^(-1))that was 2.4 and 2.8 times that of Co_(3)O_(4) and g-C_(3)N_(4) alone,respectively.The formation of heterojunctions facilitated electron transfer,enriched the electron density on Co_(3)O_(4),and enhanced the adsorption of pollutants as well as the desorption of degradation intermediates.The enhanced production of atomic hydrogen(H*)of Co_(3)O_(4)/g-C_(3)N_(4),which increased by 13.6-28.2 times,contributed more to pollutant removal(64.0%),much higher than that of Co_(3)O_(4)(37.3%)and g-C_(3)N_(4)(6.1%).The energy barrier for H_(2) formation on Co_(3)O_(4)/g-C_(3)N_(4)(0.75 eV)was higher than that on Co_(3)O_(4)(-1.84 eV),supporting that it could stabilize H*and inhibit the formation of H_(2).The Co_(3)O_(4)/g-C_(3)N_(4) heterojunction exhibited stable performance with less impact by pH and co-existing ions,and posed effectiveness for the dechlorination of typical chlorinated antibiotics.This study offers an efficient and sustainable strategy for constructing heterojunctions to enhance the performance of non-noble metal catalysts in electrocatalytic dechlorination. 展开更多
关键词 Electrocatalytic dechlorination CO_(3)O_(4)/g-C_(3)N_(4) HETEROJUNCTIONS atomic hydrogen Chlorinated antibiotics
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Double-layer model updating for steel-concrete composite beam cable-stayed bridge based on GPS 被引量:1
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作者 刘云 钱振东 《Journal of Southeast University(English Edition)》 EI CAS 2008年第1期80-84,共5页
In order to establish the relationship between the measured dynamic response and the health status of long-span bridges, a double-layer model updating method for steel-concrete composite beam cable-stayed bridges is p... In order to establish the relationship between the measured dynamic response and the health status of long-span bridges, a double-layer model updating method for steel-concrete composite beam cable-stayed bridges is proposed. Measured frequencies are selected as the first-layer reference data, and the mass of the bridge deck, the grid density, the modulus of concrete and the ballast on the side span are modified by using a manual tuning technique. Measured global positioning system (GPS) data is selected as the second-layer reference data, and the degradation of the integral structure stiffness EI of the whole bridge is taken into account for the second-layer model updating by using the finite element iteration algorithm. The Nanpu Bridge in Shanghai is taken as a case to verify the applicability of the proposed model updating method. After the first-layer model updating, the standard deviation of modal frequencies is smaller than 7%. After the second-layer model updating, the error of the deflection of the mid-span is smaller than 10%. The integral structure stiffness of the whole bridge decreases about 20%. The research results show a good agreement between the calculated response and the measured response. 展开更多
关键词 steel-concrete composite beam GPS dynamic respond double-layer model updating
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Computation of the Fatigue Life of Road Wheel with Double-Layer Rubber Flange
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作者 郑慕侨 孙逢春 +1 位作者 蒋轩 张军 《Journal of Beijing Institute of Technology》 EI CAS 2001年第2期169-174,共6页
In order to increase the fatigue life (FL) of road wheels (RW), a kind of double layer rubber flange (DLRF) is put forward. It consists of two layers of rubber, where metal wires are laid in the inner layer and the ou... In order to increase the fatigue life (FL) of road wheels (RW), a kind of double layer rubber flange (DLRF) is put forward. It consists of two layers of rubber, where metal wires are laid in the inner layer and the outer layer has no inlaid metal wires. Stress, strain and temperature field of DLRF were calculated with ANSYS finite element analysis (FEA) software, FL of DLRF RW was also computed with fracture mechanics fatigue theory. The results of computation indicate that the heat generated in RW's rubber flange (RF) can be reduced by the use of DLRF, and the FL of RW can be increased without affecting the mechanical intensity of RW. 展开更多
关键词 double-layer rubber flange road wheel finite element analysis fatigue life
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Design and evaluation of a Laval-type supersonic atomizer for low-pressure gas atomization of molten metals 被引量:7
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作者 Chao-run Si Xian-jie Zhang +1 位作者 Jun-biao Wang Yu-jun Li 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2014年第6期627-635,共9页
A Laval-type supersonic gas atomizer was designed for low-pressure gas atomization of molten metals. The principal design ob-jectives were to produce small-particle uniform powders at lower operating pressures by impr... A Laval-type supersonic gas atomizer was designed for low-pressure gas atomization of molten metals. The principal design ob-jectives were to produce small-particle uniform powders at lower operating pressures by improving the gas inlet and outlet structures and op-timizing structural parameters. A computational fluid flow model was developed to study the flow field characteristics of the designed atom-izer. Simulation results show that the maximum gas velocity in the atomization zone can reach 440 m&#183;s-1;this value is independent of the atomization gas pressure P0 when P0〉0.7 MPa. When P0=1.1 MPa, the aspiration pressure at the tip of the delivery tube reaches a mini-mum, indicating that the atomizer can attain the best atomization efficiency at a relatively low atomization pressure. In addition, atomization experiments with pure tin at P0=1.0 MPa and with 7055Al alloy at P0=0.8 and 0.4 MPa were conducted to evaluate the atomization capa-bility of the designed atomizer. Nearly spherical powders were obtained with the mass median diameters of 28.6, 43.4, and 63.5μm, respec-tively. Compared with commonly used atomizers, the designed Laval-type atomizer has a better low-pressure gas atomization capability. 展开更多
关键词 atomizers gas atomization supersonic flow simulation metal powders
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Microscopic and macroscopic atomization characteristics of a pressure-swirl atomizer, injecting a viscous fuel oil 被引量:6
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作者 Seyed Mohammad Ali Najafi Pouria Mikaniki Hojat Ghassemi 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2020年第1期9-22,共14页
Combustion of heavy fuels is one of the main sources of greenhouse gases, particulate emissions, ashes, NOxand SOx. Gasification is an advanced and environmentally friendly process that generates combustible and clean... Combustion of heavy fuels is one of the main sources of greenhouse gases, particulate emissions, ashes, NOxand SOx. Gasification is an advanced and environmentally friendly process that generates combustible and clean gas products such as hydrogen. Some entrained flow gasifiers operate with Heavy Fuel Oil(HFO) feedstock. In this application, HFO atomization is very important in determining the performance and efficiency of the gasifiers.The atomization characteristics of HFO(Mazut) discharging from a pressure-swirl atomizer(PSA) are studied for different pressures difference(Δp) and temperatures in the atmospheric ambient. The investigated parameters include atomizer mass flow rate( _m), discharge coefficient(CD), spray cone angle(θ), breakup length(Lb), the unstable wavelength of undulations on the liquid sheet(λs), global and local SMD(sauter mean diameter) and size distribution of droplets. The characteristics of Mazut sheet breakup are deduced from the shadowgraph technique. The experiments on Mazut film breakup were compared with the predictions obtained from the liquid film breakup model. Validity of the theory for predicting maximum unstable wavelength was investigated for HFO(as a highly viscous liquid). A modification on the formulation of maximum unstable wavelength was presented for HFO. SMD decreases by getting far from the atomizer. The measurement for SMD and θ were compared with the available correlations. The comparisons of the available correlations with the measurements of SMD andθ show a good agreement for Ballester and Varde correlations, respectively. The results show that the experimental sizing data could be presented by Rosin-Rammler distributions very well at different pressure difference and temperatures. 展开更多
关键词 GASIFIER Heavy fuel oil atomIZATION Pressure-swirl atomizer Mazut Size distribution Wavelength Viscosity
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Double-layered osmotic pump controlled release tablets of actarit: In vitro and in vivo evaluation 被引量:9
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作者 Yuenan Li Hao Pan +6 位作者 Hongliang Duan Jianting Chen Zhihong Zhu Jingxin Fan Pingfei Li Xinggang Yang Weisan Pan 《Asian Journal of Pharmaceutical Sciences》 SCIE CAS 2019年第3期340-348,共9页
The aim of the study was to develop actarit double-layered osmotic pump tablets to overcome the weak points of actarit common tablets, such as short half-life and large plasma concentration fluctuations. Single factor... The aim of the study was to develop actarit double-layered osmotic pump tablets to overcome the weak points of actarit common tablets, such as short half-life and large plasma concentration fluctuations. Single factor experiment and orthogonal test were applied to optimize the formulation;the pharmacokinetic study was performed in beagle dogs adopting actarit common tablets as reference tablets. The optimal formulation was as follows: drug layer: 150 mg actarit, 240 mg PEO-N80, 50 mg NaCl;push layer: 140 mg PEO-WSR303, 20 mg NaCl;coating solution: 30 g cellulose acetate and 6 g PEG 4000 in 1000 ml 94% acetone solution, 60 mg coating weight gain. The pharmacokinetic study showed that T max was prolonged by the contrast of commercial common tablets with constant drug release rate, but the bioavailability was equivalent. And a good in vivo –in vitro correlation of the actarit osmotic pump tablets was also established. The designed actarit osmotic pump tablets can be applied for rheumatoid arthritis, proposing a promising replacement for the marked common products. 展开更多
关键词 Actarit double-layered OSMOTIC pump TABLET PHARMACOKINETICS In vivo –in VITRO correlation
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Double-layered covered stent for the treatment of malignant oesophageal obstructions: Systematic review and meta-analysis 被引量:2
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作者 Zeiad Hussain Athanasios Diamantopoulos +1 位作者 Miltiadis Krokidis Konstantinos Katsanos 《World Journal of Gastroenterology》 SCIE CAS 2016年第34期7841-7850,共10页
AIM To investigate the efficacy of double-layered covered stent in the treatment of malignant oesophageal obstructions.METHODS A systematic review and meta-analysis was performed following the PRISMA process. Pub Med(... AIM To investigate the efficacy of double-layered covered stent in the treatment of malignant oesophageal obstructions.METHODS A systematic review and meta-analysis was performed following the PRISMA process. Pub Med(Medline),EMBASE(Excerpta Medical Database),AMED(Allied and Complementary medicine Database),Scopus and online content,were searched for studies reporting on the Ni Ti-S polyurethane-covered double oesophageal stent for the treatment of malignant dysphagia. Weighted pooled outcomes were synthesized with a random effects model to account for clinical heterogeneity. All studies reporting the outcome of palliative management of dysphagia due to histologically confirmed malignant oesophageal obstruction using double-layered covered nitinol stent were included. The level of statistical significance was set at α = 0.05.RESULTS Six clinical studies comprising 250 patients in total were identified. Pooled technical success of stent insertion was 97.2%(95%CI: 94.8%-98.9%; I2 = 5.8%). Pooled complication rate was 27.6%(95%CI: 20.7%-35.2%; I2 = 41.9%). Weighted improvement of dysphagia on a scale of 0-5 scoring system was-2.00 [95%CI:-2.29%-(-1.72%); I2 = 87%]. Distal stent migration was documented in 10 out of the 250 cases examined.Pooled stent migration rate was 4.7%(95%CI: 2.5%-7.7%; I2 = 0%). Finally,tumour overgrowth was reported in 34 out of the 250 cases with pooled rate of tumour overgrowth of 11.2%(95%CI: 3.7%-22.1%; I2 = 82.2%). No funnel plot asymmetry to suggest publication bias(bias = 0.39,P = 0.78). In the sensitivity analysis all results were largely similar between the fixed and random effects models.CONCLUSION The double-layered nitinol stent provides immediate relief of malignant dysphagia with low rates of stent migration and tumour 展开更多
关键词 double-layered covered STENT MALIGNANT OESOPHAGEAL OBSTRUCTIONS Dysphagia double-layered nitinol STENT
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One-dimensional consolidation of double-layered soil with non-Darcian flow described by exponent and threshold gradient 被引量:10
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作者 李传勋 谢康和 +1 位作者 胡安峰 胡白香 《Journal of Central South University》 SCIE EI CAS 2012年第2期562-571,共10页
Based on non-Darcian flow law described by exponent and threshold gradient within a double-layered soil, the classic theory of one-dimensional consolidation of double-layered soil was modified to consider the change o... Based on non-Darcian flow law described by exponent and threshold gradient within a double-layered soil, the classic theory of one-dimensional consolidation of double-layered soil was modified to consider the change of vertical total stress with depth and time together. Because of the complexity of governing equations, the numerical solutions were obtained in detail by finite difference method. Then, the numerical solutions were compared with the analytical solutions in condition that non-Darcian flow law was degenerated to Dary's law, and the comparison results show that numerical solutions are reliable. Finally, consolidation behavior of double-layered soil with different parameters was analyzed, and the results show that the consolidation rate of double-layered soil decreases with increasing the value of exponent and threshold of non-Darcian flow, and the exponent and threshold gradient of the first soil layer greatly influence the consolidation rate of double-layered soil. The larger the ratio of the equivalent water head of external load to the total thickness of double-layered soil, the larger the rate of the consolidation, and the similitude relationship in classical consolidation theory of double-layered soil is not satisfied. The other consolidation behavior of double-layered soil with non-Darcian flow is the same as that with Darcy's law. 展开更多
关键词 one-dimensional consolidation double-layered soil non-Darcian flow depth dependent vertical total stress timedependent loading
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Numerical investigation of velocity distribution of turbulent flow through vertically double-layered vegetation 被引量:5
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作者 Naveed Anjum Norio Tanaka 《Water Science and Engineering》 EI CAS CSCD 2019年第4期319-329,共11页
The velocity structures of flow through vertically double-layered vegetation(VDLV)as well as single-layered rigid vegetation(SLV)were investigated computationally with a three-dimensional(3D)Reynolds stress turbulence... The velocity structures of flow through vertically double-layered vegetation(VDLV)as well as single-layered rigid vegetation(SLV)were investigated computationally with a three-dimensional(3D)Reynolds stress turbulence model,using the computational fluid dynamics(CFD)code FLUENT.The detailed velocity distribution was explored with a varying initial Froude number(Fr),with consideration of the steady subcritical flow conditions of an inland tsunami.In VDLV flows,the numerical model successfully captured the inflection point in the profiles of mean streamwise velocities in the mixing-layer region around the top of short submerged vegetation.An upward and downward movement of flow occurred at the positions located just behind the tall and short vegetation,respectively.Overall,higher streamwise velocities were observed in the upper vegetation layer due to high porosity,with Pr=98%(sparse vegetation,where Pr is the porosity),as compared to those in the lower vegetation layer,which had comparatively low porosity,with Pr=91%(dense vegetation).A rising trend of velocities was found as the flow passed through the vegetation region,followed by a clear sawtooth distribution,as compared to the regions just upstream and downstream of vegetation where the flow was almost uniform.In VDLV flows,a rising trend in the flow resistance was observed with the increase in the initial Froude number,i.e.,Fr?0.67,0.70,and 0.73.However,the flow resistance in the case of SLV was relatively very low.The numerical results also show the flow structures within the vicinity of short and tall vegetation,which are difficult to attain through experimental measurements. 展开更多
关键词 Vertically double-layered vegetation Single-layered rigid vegetation Numerical modeling FLUENT Velocity distribution Turbulent flow
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Analysis of one-dimensional rheological consolidation of double-layered soil with fractional derivative Merchant model and non-Darcian flow described by non-Newtonian index 被引量:5
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作者 CUI Peng-lu LIU Zhong-yu +1 位作者 ZHANG Jia-chao FAN Zhi-cheng 《Journal of Central South University》 SCIE EI CAS CSCD 2021年第1期284-296,共13页
To further investigate the one-dimensional(1D)rheological consolidation mechanism of double-layered soil,the fractional derivative Merchant model(FDMM)and the non-Darcian flow model with the non-Newtonian index are re... To further investigate the one-dimensional(1D)rheological consolidation mechanism of double-layered soil,the fractional derivative Merchant model(FDMM)and the non-Darcian flow model with the non-Newtonian index are respectively introduced to describe the deformation of viscoelastic soil and the flow of pore water in the process of consolidation.Accordingly,an 1D rheological consolidation equation of double-layered soil is obtained,and its numerical analysis is performed by the implicit finite difference method.In order to verify its validity,the numerical solutions by the present method for some simplified cases are compared with the results in the related literature.Then,the influence of the revelent parameters on the rheological consolidation of double-layered soil are investigated.Numerical results indicate that the parameters of non-Darcian flow and FDMM of the first soil layer greatly influence the consolidation rate of double-layered soil.As the decrease of relative compressibility or the increase of relative permeability between the lower soil and the upper soil,the dissipation rate of excess pore water pressure and the settlement rate of the ground will be accelerated.Increasing the relative thickness of soil layer with high permeability or low compressibility will also accelerate the consolidation rate of double-layered soil. 展开更多
关键词 double-layered soil rheological consolidation fractional derivative non-Darcian flow non-Newtonian index finite difference method viscoelasticity
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Analysis on Connectivity of Inter-Orbit-Links in a MEO/LEO Double-Layer Satellite Network 被引量:3
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作者 王振永 李集林 +1 位作者 郭庆 顾学迈 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2006年第4期340-345,共6页
As an important scheme of future global mobile satellite communication systems to provide multimedia service, a Double-Layer Satellite Network (DLSN) with MEO satellites and LEO satellites is proposed. The Inter-Orb... As an important scheme of future global mobile satellite communication systems to provide multimedia service, a Double-Layer Satellite Network (DLSN) with MEO satellites and LEO satellites is proposed. The Inter-Orbit-Links (IOLs) between layers is an essential factor, which affects the performances of the DLSN systems. Considering certain constellation parameters, the geometric characteristics of IOLs are described and the connectivity of MEO satellites and LEO satellites in the DLSN is analyzed. By computer simulation, the results show that IOLs should be selectively established according to certain parameters rather than the simple in-sight principle. 展开更多
关键词 double-layer satellite network MEO/LEO inter-orbit-links CONNECTIVITY
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Numerical and experimental study of twin-fluid two-phase internal-mixing atomizer to develop maximum entropy method 被引量:4
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作者 Alireza MOHAMMADI Fathollah OMMI 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2020年第9期2281-2294,共14页
This paper presents an analytical, numerical, and experimental study on atomization characteristics and droplet distribution of a twin-fluid two-phase internal mixing atomizer to develop a Maximum Entropy Method(MEM).... This paper presents an analytical, numerical, and experimental study on atomization characteristics and droplet distribution of a twin-fluid two-phase internal mixing atomizer to develop a Maximum Entropy Method(MEM). A two-phase Eulerian-Lagrangian method is utilized for atomization modeling of the inside and outside atomizer. In order to modify energy and momentum sources in the MEM, parametric studies are performed, and experimental tests are carried out to verify the results by applying the shadowgraph method. An advanced test stand is developed to prepare a wide range of changes in atomization characteristics and mixing ratios. A high degree of consistency is found between numerical results from the developed MEM and experimental tests with different gas-phase pressures and liquid flow rates. The droplet diameter and velocity distribution are reviewed based on various Weber numbers, sources of energy, and momentum. Turbulence modeling assists to estimate the breakup length and time scale precisely in the developed MEM, and distribution ranges with mean values are achieved. With reference to a strong correlation between upstream turbulence flow and the developed MEM verified by experimental tests, an ideal droplet size and velocity distribution prediction is observed. 展开更多
关键词 atomIZATION Droplet distribution Internal-mixing atomizer Maximum entropy method Shadowgraph technique Test stand
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