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Structure of Atactic Polystyrene Film Formed from aPS/CS_2 Gel

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Chinese Chemical Letters 1996年第10期7卷 942-943页

作者： yan Xiang WANG Wen Hui SONG de yan shen(Polymer Physics Laboratory, Institute of Chemistry, Academia Sinica, Beijing 100080) Polymer Physics Laboratory Institute of Chemistry Academia Sinica Beijing 100080

Novel ordered structure was detected in atactic polystyrene(aPS)formed from aPS/CS2 gel,the ordered structure is constructed through stacks of stereoregular segments by accepting TTGG type conformation. Another anomalous phenomenon was that many particles with different shape and size formed on surface of the film, these were some special aggregates with more orderedstructure.

关键词：梗梗 Structure of Atactic Polystyrene Film Formed from aPS/CS2 Gel CS

RECOVERY OF AMORPHOUS POLY(ETHYLENE TEREPHTHALATE)FILM UNIAXIALLY DRAWN JUST BELOW THE GLASS TRANSITION TEMPERATURE

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Chinese Journal of Polymer Science 2000年第1期18卷 69-75页

作者： Nan-jian Sun Juan yang de-yan shen Ren-yuan Qian Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, China 中科院化学所北京

Isothermal recovery in the macroscopic length of homogeneously deformed specimens of amorphous poly(ethylene terephthalate) (PET) film sample uniaxially drawn at 69 degrees C to the draw ratios lambda(0) = 1.26-2.20 were studied at temperatures around the glass transition temperature (T-g = 73 degrees C). Experimental results indicate that the length recovery look place in two distinct steps: a fast first step (fast relaxation) followed by a slow second step (slow relaxation). The relaxation processes were accompanied by the reversion of trans-conformers (1340 cm(-1)) to gauche, and the dichroic function of the 1340 cm(-1) band characterizing the segmental orientation along the chain direction decreased to a very low value at the end of the fast relaxation. This fact led us to assign the fast relaxation as the segmental orientation while the slow relaxation as relaxation of the global chain orientation. It was found that the slow relaxation follows a single exponential function, with relaxation times strongly dependent on the temperature resembling the glass transition process. The fast relaxation does not follow a single exponential decay, presumably a distribution of relaxation times is involved.

关键词： poly(ethylene terephthalate) uniaxial drawing recovery orientation

Recovery of Uniaxially Stretched Amorphous Poly(ethylene terephthalate) Film

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Chinese Chemical Letters 1998年第10期9卷 965-966页

作者： Nan Jian SUN and de yan shen(Polymer Physics Laboratory, Institute of Chemistry,Chinese Academy of Sciences, Beding, 100080.) Polymer Physics Laboratory Institute of Chemistry Chinese Academy of Sciences Beijing 100080 China

Recovery behavior of uniaxially stretched amorphous poly(ethylene terephthalate) (a-PET) film near glass transition temperature (T-g) was studied. A strain recovery curve showed that the recovery was made up of two co... 详细信息

关键词： polyethylene terephthalate uniaxial stretching relaxation recovery

VISCOELASTIC BEHAVIOR OF THE NON-HOOKE deFORMATION BEFORE YIELDING IN UNIAXIAL DRAWING OF AMORPHOUS POLY(ETHYLENE TEREPHTHALATE)

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Chinese Journal of Polymer Science 2001年第4期19卷 399-405页

作者： Zhen-hua Yuan de-yan shen Ren-yuan Qian Polymer Physics Laboratory Center for Molecular Science, Institute of Chemistry Chinese Academy of Sciences, Beijing 100080 China 中科院化学所高分子物理及化学国家重点实验室北京

Viscoelastic behavior of the non-Hooke deformation of amorphous PET film before yield was investigated in the temperature region 74-80.5 degreesC around the glass transition temperature. The film specimen was drawn to yield point followed by unloading to zero stress, then the residual deformation was held constant; while the subsequent evolution of the stress was recorded. An induction period was found in the course of stress evolution followed by a stress step-increase. The induction period decreases with increasing drawing temperature with an activation energy of 1.10 MJ/mol.K, which is attributed to the time needed for the relaxation of rubbery deformation through cooperative internal rotations. At temperatures lower than 74 degreesC, there is no stress increase or the induction period becomes too long to be observed. Thus the nature of anelasticity in the non-Hooke region before yielding is attributed to stress induced rubbery deformation. The experimental results are interpreted in terms of Perez' theological model of a series connected Hooks spring and a Voigt element consisting of a parallel connected elastic spring and a dashpot.

关键词： pre-yield deformation PET uniaxial drawing non-Hooke deformation viscoelasticity stress induced rubbery deformation

Stereocomplex Formation of Atactic Poly(methyl mcthacrylate)

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Chinese Chemical Letters 2000年第5期11卷 405-406页

作者： Qun GU de yan shen (Polymer Physics Laboratory, Center for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Bet.jing 100080) Polymer Physics Laboratory Center for Molecular Science Chinese Academy of Sciences Beijing 100080 China

Stereocomplexes formed in atactic poly(methyl methacrylatc) (α-PMMA) films cast form different solvents were studied by means of Fourier transform infrared spectroscopy (FTIR). and differential scanning calorimetry (... 详细信息

关键词： Atactic poly(methyl methacrylate) stereocomplex annealing.

Multiple Melting Endotherms of Syndiotactic Polystyrene in β Crystalline Form

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Chinese Chemical Letters 2000年第4期11卷 367-368页

作者： Zhen Hua YUAN de yan shen (Polymer Physics Laboratory, Center for Molecular Science. Institute of Chemistry. Chinese Academy of Sciences, Beijing 100080) Polymer Physics Laboratory Center for Molecular Science Chinese Academy of Sciences Beijing 100080 China

A series of syndiotactic polystyrene (SPS) samples in β crystalline form were prepared by cooling from the melt at various cooling rates. The effects of cooling rate from the melt, and DSC heating rate on the multiple melting behaviors of β crystals were investigated by differential scanning calorimetry (DSC) and modulated differential scanning calorimetry (MDSC), from which the *** the multiple melting behavior was ascribed to the occurring of a recrystallization process.

关键词： Multiple melting behavior syndiotactic polystyrene recrystalliation.

A Novel Locomotion Rule Rmbedding Long Short-Term Memory Network with Attention for Human Locomotor Intent Classification Using Multi-Sensors Signals

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Computers, Materials & Continua 2024年第6期79卷 4349-4370页

作者： Jiajie shen yan Wang Dongxu Zhang Key Laboratory of Symbol Computation and Knowledge Engineering Ministry of EducationColleague of Computer Science and TechnologyJilin UniversityChangchun130012China College of Software and Key Laboratory of Symbolic Computation and Knowledge Engineering of Ministry of EducationJilin UniversityChangchun130012China

Locomotor intent classification has become a research hotspot due to its importance to the development of assistive robotics and wearable *** work have achieved impressive performance in classifying steady locomotion ***,it remains challenging for these methods to attain high accuracy when facing transitions between steady locomotion *** to the similarities between the information of the transitions and their adjacent steady ***,most of these methods rely solely on data and overlook the objective laws between physical activities,resulting in lower accuracy,particularly when encountering complex locomotion modes such as *** address the existing deficiencies,we propose the locomotion rule embedding long short-term memory(LSTM)network with Attention(LREAL)for human locomotor intent classification,with a particular focus on transitions,using data from fewer sensors(two inertial measurement units and four goniometers).The LREAL network consists of two levels:One responsible for distinguishing between steady states and transitions,and the other for the accurate identification of locomotor *** classifier in these levels is composed of multiple-LSTM layers and an attention *** introduce real-world motion rules and apply constraints to the network,a prior knowledge was added to the network via a rule-modulating *** method was tested on the ENABL3S dataset,which contains continuous locomotion date for seven steady and twelve transitions *** results showed that the LREAL network could recognize locomotor intents with an average accuracy of 99.03%and 96.52%for the steady and transitions states,*** is worth noting that the LREAL network accuracy for transition-state recognition improved by 0.18%compared to other state-of-the-art network,while using data from fewer sensors.

关键词： Lower-limb prosthetics deep neural networks motion classification

Growth process,defects,and dopants of bulkβ-Ga_(2)O_(3)semiconductor single crystals

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China Foundry 2024年第5期21卷 491-506页

作者： yan-shen Wang Ming-zhi Zhu Yuan Liu School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China Key Laboratory for Advanced Materials Processing Technology(Ministry of Education) Beijing 100084China

β-gallium oxide(β-Ga2O3),as the typical representative of the fourth generation of semiconductors,has attracted increasing attention owing to its ultra-wide bandgap,superior optical properties,and excellent tolerance to high temperature and *** to the single crystals of other semiconductors,high-quality and large-sizeβ-Ga_(2)O_(3)single crystals can be grown with low-cost melting methods,making them highly *** this review,the growth process,defects,and dopants ofβ-Ga_(2)O_(3)are primarily ***,the growth process(e.g.,decomposition,crucible corrosion,spiral growth,and development)ofβ-Ga_(2)O_(3)single crystals are summarized and compared in ***,the defects ofβ-Ga_(2)O_(3)single crystals and the influence of defects on Schottky barrier diode(SBD)devices are emphatically ***,the influences of impurities and intrinsic defects on the electronic and optical properties ofβ-Ga_(2)O_(3)are also briefly *** this comprehensive analysis,the article offers a concise summary of the current state,challenges and prospects ofβ-Ga_(2)O_(3)single crystals.

关键词： β-Ga_(2)O_(3) single-crystal growth defects dopants semiconductor

Sedimentary and Heavy Mineral Records for the Oligocene-Miocene Exhumation of the Easternmost Tianshan

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Journal of Earth Science 2024年第2期35卷 449-461页

作者： yan Ding Tianyi shen Guocan Wang Junliang Ji School of Earth Sciences Center for Global TectonicsChina University of GeosciencesWuhan430074China State Key Laboratory of Geological Processes and Mineral Resources China University of GeosciencesWuhan430078China Hubei Key Laboratory of Critical Zone Evolution School of Geography and Information EngineeringChina University of GeosciencesWuhan430074China

The topography of the Harlik Mountain has a strong impact on the formation of current arid climate in the Turpan-Hami ***,it is still controversial if Harlik Mountain experienced significant exhumation during the Middle to Late Cenozoic according to the previous thermochronology *** features of the Oligocene to Miocene sediments in the foreland basin could provide productive information for resolving the *** peak ages of detrital apatite fission track analysis of the Oligocene–Miocene sandstone in the Turpan-Hami Basin are well comparable with the cooling age records of the Harlik Mountain rocks,indicating that the Oligocene–Miocene Taoshuyuanzi Formation in the basin was mostly derived from the Harlik *** stratigraphic sequence exhibits coarsening upward,reflecting that the source area was in a tectonically active period during the deposition *** mineral assemblages also suggest that the unstable minerals in the sediment increased significantly at the end of the ***,the proportion of apatite increased up-section,while the garnet content decreased significantly,indicating that the Carboniferous metamorphic rocks have been gradually eroded out and more intrusive rocks have been exposed to the *** observations suggest that the Harlik Mountain experienced exhumation during the Oligocene to Miocene,and the denudation depth afterward was probably less than 2.5 km according to the previously apatite(U-Th)/He *** Oligocene–Miocene exhumation probably acted as one of the triggers for the heavy drought of the Turpan-Hami Basin during the Middle–Late Neogene.

关键词： Turpan-Hami Basin Harlik Mountain Taoshuyuanzi Formation Oligocene–Miocene uplift sedimentology structural geology