检索结果-南通市图书馆

Cellulose Acetate Thermoplastics with High Modulus, Dimensional Stability and Anti-migration Properties by Using CA-g-PLA as Macromolecular Plasticizer

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2020年第10期38卷 1141-1148页

作者： ru-meng xu Tian-Tian Yang Elvira Vidovi? ruo-Nan Jia Jin-Ming Zhang Qin-Yong Mi Jun Zhang CAS Key Laboratory of Engineering Plastics CAS Research/Education Center for Excellence in Molecular Sciences Institute of Chemistry Chinese Academy of Sciences (CAS) University of Chinese Academy of Sciences Faculty of Chemical Engineering and Technology University of Zagreb

Cellulose diacetate(CDA) can be melt-processed to produce numerous and widely-used plastic ***,due to the high glass transition temperature(Tg) of CDA,the addition of up to 30 wt% of micromolecular plasticizers is indispensable,which significantly reduces the dimensional stability and raises safety concerns from the migration of *** this work,a series of CDA-graft-poly(lactic acid)(CDA-gPLA) copolymers were synthesized by ring-opening polymerization of lactide onto the hydroxyl groups of *** resultant CDA-g-PLA copolymers possess adjustable degrees of substitution(DSPLA) and side chain length(DPPLA) by controlling the reaction time and feed *** Tgs and thermal flow temperatures(Tfs) of CDA-g-PLA strongly depend on DPPLA,such as the Tgs decrease linearly with the increase of *** CDA-g-PLA copolymers with the DPPLAof 3-9 can be directly processed to transparent plastics by melt processing without any external plasticizers,because of their low Tfs of 170-215 ℃.More impressively,the CDA-g-PLA can act as the macromolecular *** obtained CDA/CDA-g-PLA has higher storage modulus,flexural modulus and Young’s modulus than the commercial CDA plasticized with triethyl *** addition,the CDA/CDA-g-PLA exhibits high dimensional stability and anti-migration *** a long-term treatment at 80℃ and 60% humidity,the CDA/CDA-g-PLA can retain the initial ***,this work not only proposes a facile method for achieving a direct thermoplastic processing of CDA,but also provides a macromolecular plasticizer for CDA to make lightweight,stable and safer biobased thermoplastics.

关键词： Cellulose diacetate Thermoplastic processing Macromolecular plasticizer Poly(lactic acid)

Influence of tectonic preservation conditions on the nanopore structure of shale reservoir: A case study of Wufeng-Longmaxi Formation shale in western Hubei area, south China

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Petroleum Science 2024年第4期21卷 2203-2217页

作者： meng Xiang Shang xu Ya-ru Wen Qi-Yang Gou Bing-Chang Liu National Key Laboratory of Deep Oil and Gas China University of Petroleum (East China) Hubei Key Laboratory of Resources and Eco-environment Geology Hubei Geological Survey Key Laboratory of Tectonics and Petroleum Resources Ministry of Education China University of Geosciences

Tectonism is one of the dominant factors affecting the shale pore structure. However, the control of shale pore structure by tectonic movements is still controversial, which limits the research progress of shale gas accumulation mechanism in the complex tectonic region of southern China. In this study, 34 samples were collected from two exploratory wells located in different tectonic locations. Diverse experiments,e.g., organic geochemistry, XRD analysis, FE-SEM, low-pressure gas adsorption, and high-pressure mercury intrusion, were conducted to fully characterize the shale reservoir. The TOC, Ro, and mineral composition of the shale samples between the two wells are similar, which reflects that the shale samples of the two wells have proximate pores-generating capacity and pores-supporting ***, the pore characteristics of shale samples from two wells are significantly different. Compared with the stabilized zone shale, the porosity, pore volume, and specific surface area of the deformed zone shale were reduced by 60.61%, 64.85%, and 27.81%, respectively. Moreover, the macroscopic and fine pores were reduced by 54.01% and 84.95%, respectively. Fault activity and uplift denudation are not conducive to pore preservation, and the rigid basement of Huangling uplift can promote pore preservation. These three factors are important reasons for controlling the difference in pore structure between two wells shales. We established a conceptual model of shale pores evolution under different tectonic preservation conditions. This study is significant to clarify the scale of shale gas formation and enrichment in complex tectonic regions, and helps in the selection of shale sweet spots.

关键词： Shale gas Pore structure Tectonic preservation conditions Shale gas enrichment mechanism

Accuracy of Mean Value of Central Venous Pressure from Monitor Digital Display: Influence of Amplitude of Central Venous Pressure during Respiration

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Medical Sciences Journal 2023年第2期38卷 117-124页

作者： meng-ru xu Wang-Lin Liu Huai-Wu He Xiao-Li Lai Mei-Ling Zhao Da-Wei Liu Yun Long Department of Critical Care Medicine State Key Laboratory of Complex Severe and Rare DiseasesPeking Union Medical HospitalPeking Union Medical College&Chinese Academy of Medical SciencesBeijing 100730China Department of Critical Care Medicine Beihai People's HosptialBeihai 536000Guangxi Zhuang Autonomous RegionChina Department of Critical Care Medicine Zibo Central HospitalMedical College of Shandong UniversityZibo 255020Shandong ProvinceChina

Background A simple measurement of central venous pressure(CVP)-mean by the digital monitor display has become increasingly ***,the agreement between CVP-mean and CVP-end(a standard method of CVP measurement by analyzing the waveform at end-expiration)is not well *** study was designed to identify the relationship between CVP-mean and CVP-end in critically ill patients and to introduce a new parameter of CVP amplitude(ΔCVP=CVPmax-CVPmin)during the respiratory period to identify the agreement/disagreement between CVP-mean and *** In total,291 patients were included in the ***-mean and CVP-end were obtained simultaneously from each *** measurement difference(|CVP-mean-CVP-end|)was defined as the difference between CVP-mean and ***ΔCVP was calculated as the difference between the peak(CVPmax)and the nadir value(CVPmin)during the respiratory cycle,which was automatically recorded on the monitor *** with|CVP-mean-CVP-end|≥2 mm Hg were divided into the inconsistent group,while subjects with|CVP-mean-CVP-end|2 mm Hg were divided into the consistent ***ΔCVP was significantly higher in the inconsistent group[7.17(2.77)vs.5.24(2.18),P0.001]than that in the consistent *** was a significantly positive relationship betweenΔCVP and|CVP-mean-CVP-end|(r=0.283,P 0.0001).Bland-Altman plot showed the bias was-0.61 mm Hg with a wide 95%limit of agreement(-3.34,2.10)of CVP-end and *** area under the receiver operating characteristic curves(AUC)ofΔCVP for predicting|CVP-mean-CVP-end|≥2 mm Hg was *** a high diagnostic specificity,usingΔCVP3 to detect|CVP-mean-CVP-end|lower than 2mm Hg(consistent measurement)resulted in a sensitivity of 22.37%and a specificity of 93.06%.UsingΔCVP8 to detect|CVP-mean-CVPend|8 mm Hg(inconsistent measurement)resulted in a sensitivity of 31.94%and a specificity of 91.32%.Conclusions CVP-end and CVP-mean have statistical discrepancies in specific clinical sce

关键词： central venous pressure monitor digital display monitor cursor-line display respiration

Multi-Stream Temporally Enhanced Network for Video Salient Object Detection

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2024年第1期78卷 85-104页

作者： Dan xu Jiale ru Jinlong Shi School of Computer Science Jiangsu University of Science and TechnologyZhenjiang212100China

Video salient object detection(VSOD)aims at locating the most attractive objects in a video by exploring the spatial and temporal *** poses a challenging task in computer vision,as it involves processing complex spatial data that is also influenced by temporal *** the progress made in existing VSOD models,they still struggle in scenes of great background diversity within and between ***,they encounter difficulties related to accumulated noise and high time consumption during the extraction of temporal features over a long-term *** propose a multi-stream temporal enhanced network(MSTENet)to address these *** investigates saliency cues collaboration in the spatial domain with a multi-stream structure to deal with the great background diversity challenge.A straightforward,yet efficient approach for temporal feature extraction is developed to avoid the accumulative noises and reduce time *** distinction between MSTENet and other VSOD methods stems from its incorporation of both foreground supervision and background supervision,facilitating enhanced extraction of collaborative saliency *** notable differentiation is the innovative integration of spatial and temporal features,wherein the temporal module is integrated into the multi-stream structure,enabling comprehensive spatial-temporal interactions within an end-to-end *** experimental results demonstrate that the proposed method achieves state-of-the-art performance on five benchmark datasets while maintaining a real-time speed of 27 fps(Titan XP).Our code and models are available at https://***/ruJiaLe/MSTENet.

关键词： Video salient object detection deep learning temporally enhanced foreground-background collaboration

Decomposition mechanisms of nuclear-grade cationic exchange resin by advanced oxidation processes:Statistical molecular fragmentation model and DFT calculations

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2024年第1期135卷 433-448页

作者： Xiang meng Pierre Désesquelles Lejin xu Department of Nuclear Engineering and Technology School of Energy and Power EngineeringHuazhong University of Science&TechnologyWuhan 430074China CNRS Laboratoire de Physique des Gaz et des PlasmasUniversitéParis-SaclayOrsay 91405France State Key Laboratory of Coal Combustion School of Energy and Power EngineeringHuazhong University of Science and TechnologyWuhan 430074China

The treatment and disposal of radioactive waste are presently facing great *** ion exchange resins have become a focus of attention due to their high production and serious environmental *** this paper,a simplified model of cationic exchange resin is proposed,and the degradation processes of cationic resin monomer initiated by hydroxyl radicals(·OH)are clarified by combining statistical molecular fragmentation(SMF)model and density functional theory(DFT)*** prediction of active sites indicates that the S-O bonds and the C-S bond of the sulfonic group are more likely to react during the *** meta-position of the sulfonic group on the benzene ring is the most active site,and the benzene ring without the sulfonic group has a certain *** C11-C14 and C17-C20 bonds,on the carbon skeleton,are the most easily *** is also found that dihydroxy addition and elimination reactions play a major role in the process of desulfonation,carbon skeleton cleavage and benzene ring *** decomposition mechanisms found through the combination of physical models and chemical calculations,provide theoretical guidance for the treatment of complex polycyclic aromatic hydrocarbons.

关键词： Cationic exchange resin Statistical molecular fragmentation model Density functional theory Hydroxyl radical Decomposition mechanism

Cellulose Acetate Thermoplastics with High Modulus, Dimensicnal Stability and Anti-migration Properties by Using CA-g-PLA as Macromolecular Plasticizer

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2020年第10期38卷 1141-1148,I0008页

作者： ru-meng xu Tian-Tian Yang Elvira Vidovic ruo-Nan Jia Jin-Ming Zhang Qin-Yong Mi Jun Zhang CAS Key Laboratory of Engineering Plastis CAS Research/Education Center for Exellence in Molecular SciencesIstute of Chemistry.Chinese Academy of Sciences(CAS)Beijing 100190China University ofChinese Academy ofSciences Bejing 10049 China Faculty ofChemical Engineering and Technology.University ofZagreb Zagreb 1000Croatia

Cellulose diacetate(CDA)can be melt processed to produce numerous and widely-used plastic ***,due to the high glass transition temperature(Tg)of CDA,the addition of up to 30 wt%of micromolecular plasticizers is indispensable,which significantly reduces the dimensional stability and raises safety concerns from the migration of *** this work,a series of CDA-graft poly(lactic acid)(CDA-g-PLA)copolymers were synthesized by ring-opening polymerization of lactide onto the hydroxyI groups of *** resultant CDA-g-PLA copolymers possess adjustable degrees of substitution(DSpua)and side chain length(DPpLa)by controlling the reaction time and feed *** Tgs and thermal flow temperatures(Ts)of CDA-g-PLA strongly depend on DPpA such as the Tgs decrease linearly with the increase of *** CDA-g-PLA copolymers with the DPLA of 3-9 can be directly processed to transparent plastics by melt processing without any external plasticizers,because of their low Tfs of 170-215℃.More *** CDA-g PLA can act as the macromolecular *** obtained CDA/CDA-g-PLA has higher storage modulus,flexural modulus and Young's modulus than the commercial CDA plasticized with triethyl *** addition,the CDA/CDA-g PLA exhibits high dimensional stabilty and anti-migration *** a long term treatment at 80℃ and 60%humidity,the CDA/CDA-g-PLA can retain the initial ***,this work not only proposes a facile method for achieving a direct thermoplastic processing of CDA,but also provides a macromolecular plasticizer for CDA to make lightweight,stable and safer biobased thermoplastics.

关键词： Cellulose diacetate Thermoplastic processing Macromolecular plasticizer Poly(actic acid)

GNSS gyroscopes:determination of angular velocity and acceleration with very high-rate GNSS

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Satellite Navigation 2024年第1期5卷 74-90页

作者： Yun Shi Peiliang xu Yuanming Shu Xiaolin meng School of Geomatics Xi’an University of Science and TechnologyXi’an710054People’s Republic of China Disaster Prevention Research Institute Kyoto UniversityUjiKyoto611-0011Japan College of Marine Geosciences Ocean University of ChinaQingdaoPeople’s Republic of China School of Instrument Science and Engineering Southeast UniversityNanjing210096People’s Republic of China

Although global navigation satellite systems(GNSS)have been routinely applied to determine attitudes,there exists no literature on determining angular velocity and/or angular acceleration from *** by the invention of computerized accelerometers of the correspondence author and following the success of accurately recovering translational velocity and acceleration waveforms from very high-rate GNSS precise positioning by xu and his collaborators in 2021,we propose the concept of GNSS gyroscopes and reconstruct angular velocity and acceleration from very high-rate GNSS attitudes by applying regularization under the criterion of minimum mean squared *** major results from the experiments can be summarized in the following:(i)angular velocity and acceleration waveforms computed by applying the difference methods to high-rate GNSS attitudes are too noisy and can be physically not meaningful and numerically *** same can be said about inertial measurement unit(IMU)attitudes,if IMU gyros are not of very high accuracy;(ii)regularization is successfully applied to reconstruct the high-rate angular velocity and acceleration waveforms from 50 Hz GNSS attitudes and significantly outperforms the difference methods,validating the proposed concept of GNSS *** comparing the angular velocity and acceleration results by using the difference methods and regularization,we find that the peak values of angular velocity and acceleration by regularization are much smaller by a maximum factor of 1.57 in the angular velocity to a maximum factor of 8662.53 times in the angular acceleration in the case of high-rate GNSS,and by a maximum factor of 1.26 in the angular velocity to a maximum factor of 2819.85 times in the angular acceleration in the case of IMU,respectively;and(iii)the IMU attitudes apparently lead to better regularized angular velocity and acceleration waveforms than the high-rate GNSS attitudes,which can well be explained by the fact that the

关键词： Angular velocity Angular acceleration High-rate GNSS GNSS attitudes GNSS gyroscopes Regularization

Leaching kinetics and permeability of polyethyleneimine added ammonium sulfate on weathered crust elution-deposited rare earth ores

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Rare Earths 2024年第8期42卷 1610-1619,I0008页

作者： Huifang Yang Aoyang Sha Zhengyan He Chenjie Wu Yuanlai xu Jingjing Hu Zhigao xu ru'an Chi Key Laboratory for Green Chemical Process of Ministry of Education School of Resources&Safety EngineeringWuhan Institute of TechnologyWuhan 430073China Key Laboratory of Resources Conversion and Pollution Control of the State Ethnic Affairs Commission College of Resources and Environmental ScienceSouth-Central MinzuUniversityWuhan430074China

At present,in-situ leaching of weathered crust elution-deposited rare earth ores(WCE-DREOs) encounter with problems such as long leaching cycles,slow infiltration rate and low product *** order to solve the above problems,the conventional leaching agent ammonium sulfate((NH_(4))_(2)SO_(4)) was compounded with polymeric surfactant polyethyleneimine(PEI) to form a composite leaching *** effects of leaching temperature,PEI *** rate and pH on leaching kinetics and permeability of rare earths(RE) and aluminum(AI) in orebody were *** is found that with temperature increasing,the time required to reach leaching equilibrium for both RE and Al is shortened,the apparent activation energies of RE and AI are 14.79 and 13.45 kJ/mol,respectively,and the leaching processes are in accordance with the outer diffusion control,When the concentrations of(NH_(4))_(2)SO_(4) and PEI in the composite leaching agent are 2.0 wt% and 0.4 wt%;the time required to reach leaching equilibrium for RE and AI is about 50% shorter than that using(NH_(4))_(2)SO_(4) alone,and the leaching efficiencies of RE are slightly higher than that of *** increasing the temperature and flow rate of the composite leaching agent can improve the leaching efficiencies of RE and Al,but pH has neglected effects on the leaching efficiencies of *** PEI concentrations below 0,4 wt%, the addition of PEI promotes the leaching of RE and *** column leaching studies of the WCE-DREO,the addition of 0.4 wt% PEI to the traditional leaching agent(NH_(4))_(2)SO_(4) has no impact on the leaching efficiencies of ***,it can significantly increase the infiltration rate of WCE-DREO,shortening the leaching time per 10 mL effluent from about 30 min for(NH_(4))_(2)SO_(4) leaching system to 20 min for the composite leaching *** leaching time is shortened by one-third,and the leaching cost is reduced,which can provide theoretical guidance for the development and commercial implementa

关键词： Polyethyleneimine Kinetics Rare earths Permeability Activation energy

Tailoring sulfur-doped and nitrogen-defective carbon nitride nanosheets for efficient photo-controlled radical polymerizations

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2024年第7期67卷 2325-2334页

作者： xue Li meng Kai xu Yuan Huang Tao Cai Key Laboratory of Biomedical Polymers of Ministry of Education College of Chemistry and Molecular SciencesWuhan UniversityWuhan 430072China Wuhan University Shenzhen Research Institute Shenzhen 518057China

Despite the challenges that remain,the synergistic adjustment of various microstructures and photochemical parameters of graphitic carbon nitride(g-C_(3)N_(4))in photocatalytic reactions holds promises for improving catalytic efficiency and reducing energy ***,sulfur-doped and nitrogen-defective g-C_(3)N_(4)(n-SC_(3)N_(x))nanosheets were designed and elaborately *** resultant n-SC_(3)N_(x)possessed a precisely defined 2D layer structure with extensive porosity and incremental specific surface *** photoinduced electron transfer-reversible addition-fragmentation chain transfer(PET-RAFT)polymerization of vinyl monomers with low dispersity,excellent temporal control and high chain-end fidelity was achieved under mild blue light irradiation in a nondegassed *** to their ultrathin nanostructures with nitrogen defects and sulfur dopants,n-SC_(3)N_(x)was capable of catalyzing RAFT polymerization in aqueous solutions at significantly accelerated rates,which were nearly 8 times faster compared to bulk g-C_(3)N_(4).The ease of separation and efficient reusability in subsequent polymerizations was enabled by the heterogeneous nature of n-SC_(3)N_(x).The appeal of this approach was illustrated by the fact that utilizing a reusable and metal-free photocatalyst in aqueous environments allowed for the synthesis of polymers with molecular weight up to 300 kg mol^(-1) and a dispersity of 1.32.

关键词： graphitic carbon nitride nitrogen defects sulfur dopants PET-RAFT polymerization recyclability