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SOLUTION CRYSTALLIZATION BEHAVIOR OF LINEAR AND STAR-SHAPED POLY(ETHYLENE GLYCOL)-b-POLY(ε-CAPROLACTONE) BLOCK COPOLYMERS

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Chinese Journal of Polymer Science 2013年第12期31卷 1717-1724页

作者： Ting Yu Jian-qiang Zhang Ya Lia Su-dan Shen Wen-feng Wei Peng Chen 王宗宝顾群 ningbo Institute of Material Technology and Engineering Chinese Academy of Sciences School of Petrochemical Technology Lanzhou University of Technology Institute of Material Engineering Ningbo University of Technology

Lamellar crystals of diblock, triblock and four-arm poly（ethylene glycol）-b-poly（ε-caprolactone）（PEG-b-PCL） crystalline-crystalline copolymers were successfully obtained from their solution. Morphology and structure of lamellar crystals of crystalline-crystalline copotymers were investigated using tapping-mode atomic force microscopy （AFM） and selected area electron diffraction （SAED）. All of these samples showed the truncated-lozenge multilayer basal shapes with central screw dislocation or central stack, which were all obtained simultaneously from the oil bath. The diffraction pattern of PEG block lamellar crystal is attributed to the （120） diffracting planes and the pattern of PCL block lamellar crystal is attributed to the （1 I0） diffracting planes and （200） diffracting planes according to the SAED results. Four （110） crystal growth planes and two （200） crystal growth planes are discovered for the PCL blocks, but the （120） crystal growth planes of PEG blocks are hided in the figure of AFM. The crystalline structure of the four-arm copolymers （FA） is more disorder and confused than that of the diblock （DI） copolymer and the striated fold surface structures of lamellar crystals of four-arm copolymers （FA） are smoother than these of linear analogues, owing to the confused crystallization of blocks caused by the mutual restriction of blocks and the hindrance of the dendritic cores. In addition, the aspect ratio of FA is greater than that of the others. It is hypothesized that there are two reasons for the change of aspect ratios. First, the （200） diffracting planes of PCL crystals grew slowly compared to their （110） diffracting planes because of difference in the energy barrier. Secondly, edge dislocations on the （200） diffracting planes are also responsible for the variation of the aspect ratio. Consequently, the crystalline defects are augmented by the competing blocks crystallized simultaneously and the hindrance of the dendritic cores.

关键词： Lamellar crystal Topological structure PEG-b-PCL Edge dislocation Aspect ratio.

CRYSTALLIZATION BEHAVIOR, THERMAL AND MECHANICAL PROPERTIES OF PHBV/GRAPHENE NANOSHEET COMPOSITES

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Chinese Journal of Polymer Science 2013年第4期31卷 670-678页

作者： Bing-jie Wang Yu-jie Zhang Jian-qiang Zhang Qu-ting Gou Zong-bao Wang Peng Chen 顾群 ningbo Institute of Material Technology and Engineering Chinese Academy of Sciences School of Petrochemical Technology Lanzhou University of Technology

Biodegradable poly（3-hydroxybutyrate-co-3-hydroxyvalerate）（PHBV）/graphene nanosheet （GNS） composites were prepared via a solution-casting method at low GNS loadings in this work. Transmission electron microscopy revealed that a fine dispersion of GNSs was achieved in the PHBV matrix. The thermal properties of the nanocomposites were investigated by thermogravimetric analysis, and the results showed that the thermal stability of PHBV was significantly improved with a very low loading of GNSs. Nonisothermal melts crystallization behavior, spherulitic morphology and crystal structure of neat PHBV and the PHBV/GNSs nanocomposites were investigated, and the experimental results indicated that crystallization behavior of PHBV was enhanced by the presence of GNSs due to the heterogeneous nucleation effect; however, the two-dimensional （2D） GNSs might restrict the mobility of the PHBV chains in the process of crystal growing. Dynamic mechanical analysis studies showed that the storage modulus of the PHBV/GNSs nanocomposites was greatly improved.

关键词： PHBV Graphene nanosheets Nanocomposites Solution-casting films.

Influence of the electroplating pretreatment on corrosion mechanism of NdFeB magnets

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Journal of Rare Earths 2016年第2期34卷 152-157页

作者：周巧英李刚刘壮郭帅闫阿儒李东李建忠 Key Laboratory of Magnetic Materials and Devices Ningbo Institute of Material Technology and Engineering Chinese Academy of Sciences ningbo Permanent Magnetics Co. Ltd.

The electroplating pretreatment of NdFeB magnets was simulated in this study, and the effect of the pickling process on element, matrix morphology and texture was discussed. The results showed that in the ordinary circumstance the acid solution con-centration should be below 4 mol/L and the pickling time was within 120 s. However the concentration was lower than 1 mol/L and the time was about 30 s in the ultrasonic environment. The precoating technology sequentially was studied. The results revealed that there were two main reactions of the corrosion and displacement in the precoating process, and these two reactions were more obvi-ous in the grain boundary. The electrochemical analysis illustrated that the corrosion and displacement reactions were affected obvi-ously by the current density and the precoating solution temperature, usually the current density was controlled about 0.3 A/dm2, and the temperature was about 318 K in the precoating process.

关键词： NdFeB magnet pickling precoating corrosion pretreatment rare earths

Design of two-dimensional elliptically cylindrical invisible cloaks with multiple regions

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Chinese Physics B 2014年第5期23卷 257-262页

作者：罗孝阳刘道亚刘锦景董建峰 Department of Electronic Information Science and Technology Ningbo University

Two-dimensional （2D） elliptically cylindrical invisible cloaks with multiple regions are designed based on the trans-formation optics and the complementary media theory. Multiple invisible cloak regions can be obtained by properly using the compressed or folded transformation in each space layer. The constitutive parameter tensor expressions for each re- gion have been obtained. The results of full wave simulations by using finite element software confirm the validity of the constitutive parameter tensor expressions. In addition, the parameters are relatively easier to realize.

关键词： transformation optics complementary media theory elliptically cylindrical invisible cloaks

Resistive switching effects in oxide sandwiched structures

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Frontiers of Materials Science 2012年第3期6卷 183-206页

作者： Xiao-Jian ZHU Jie SHANG Run-Wei LI Key Laboratory of Magnetic Materials and Devices Ningbo Institute of Materials Technology and Engineering(NIMTE)Chinese Academy of Sciences(CAS)Ningbo 315201China Zhejiang Province Key Laboratory of Magnetic Materials and Appiication Technology Ningbo Institute of Materials Technology and Engineering(NIMTE)Chinese Academy of Sciences(CAS)Ningbo 315201China

Resistive switching （RS） behaviors have attracted great interest due to their promising potential for the data storage. Among various materials, oxide-based devices appear to be more advantageous considering their handy fabrication and compatibility with CMOS technology, though the underlying mechanism is still controversial due to the diversity of RS behaviors. In this review, we focus on the oxide-based RS memories, in which the working mechanism can be understood basically according to a so-called filament model. The filaments formation/rupture processes, approaches developed to detect and characterize filaments, several effective attempts to improve the performances of RS and the quantum conductance behaviors in oxide-based resistive random access memory （RRAM） devices are addressed, respectively.

关键词： resistive random access memory (RRAM) resistive switching (RS) oxidefilm filaments quantum conductance

Furan-containing Conjugated Polymers for Organic Solar Cells

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Chinese Journal of Polymer Science 2017年第2期35卷 171-183页

作者： Amjad Islam Zhi-yang Liu Rui-xiang Peng Wei-gang Jiang Tao Lei Wang Li Lei Zhang Rong-juan Yang Qian Guan 葛子义 ningbo Key Laboratory of Silicon and Organic Thin Film Optoelectronic Technologies Ningbo Institute of Materials Technology&EngineeringChinese Academy of SciencesNingbo 315201China University of Chinese Academy of Sciences Beijing 100049China

Development of organic semiconductors is one of the most intriguing and productive topics in material science and engineering. Many efforts have been made on the synthesis of aromatic building blocks such as benzene, thiophene and pyrrole due to the facile preparation accompanied by the intrinsic environmental stability and relatively efficient properties of the resulting polymers. In the past, furan has been less explored in this field because of its high oxidation potential. Recently, furan has attracted obsession due to its weaker aromaticity, the greater solubilities of furan-containing π-conjugated polymers relative to other benzenoid systems and the accessibility of furan-based starting materials from renewable resources. This review elaborates the advancements of organic photovoltaic polymers containing furan building blocks. The uniqueness and advantages of furan-containing building blocks in semiconducting materials are also discussed.

关键词： Conjugated polymers π-Electron Furan Semiconductors Organic solar cells

Origin of strain-induced resonances in flexible terahertz metamaterials

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Chinese Physics B 2016年第5期25卷 388-392页

作者：孙秀云郑立人李枭宁徐华梁先庭张贤鹏鲁越晖 Young-Pak Lee Joo-Yull Rhee 宋伟杰 Department of Physics and Institute of Optics Ningbo University ningbo Institute of Material Technology and Engineering Chinese Academy of Sciences Department of Physics and RINS Hanyang University Department of Physics Sungkyunkwan University

Two types of flexible terahertz metamaterials were fabricated on polyethylene naphthalate（PEN） substrates. The unit cell of one type consists of two identical split-ring resonators（SRRs） that are arranged face-to-face（i.e., Flex Meta F）; the unit cell of the other type has nothing different but is arranged back-to-back（i.e., Flex Meta B）. Flex Meta F and Flex Meta B illustrate the similar transmission dips under zero strain because the excitation of fundamental inductive–capacitive（LC）resonance is mainly dependent on the geometric structure of individual SRR. However, if a gradually variant strain is applied to bend Flex Meta F and Flex Meta B, the new resonant peaks appear： in the case of Flex Meta F, the peaks are located at the lower frequencies; in the case of Flex Meta B, the peaks appear at the frequencies adjacent to the LC resonance. The origin and evolution of strain-induced resonances are studied. The origin is ascribed to the detuning effect and the different responses to strain from Flex Meta F and Flex Meta B are associated with the coupling effect. These findings may improve the understanding on flexible terahertz metamaterials and benefit their applications in flexible or curved devices.

关键词： flexible terahertz metamaterials split ring resonator strain resonance

CRYSTALLIZATION AND MORPHOLOGY OF STAR-SHAPED POLYETHYLENOXYDE-b-POLYCAPROLACTONE UNDER HIGH PRESSURE CARBON DIOXIDE

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Chinese Journal of Polymer Science 2012年第5期30卷 623-631页

作者： Ya Li Jian Zhou Jun Li Qu-ting Gou 顾群王宗宝 ningbo Key Laboratory of Polymer Materials Ningbo Institute of Material Technology and EngineeringChinese Academy of Sciences Institute of Material Engineering Ningbo University of TechnologyNingbo315016China State Key Laboratory of Polymer Materials Engineering(Sichuan University) Polymer Research Institute of Sichuan University

Atomic force microscopy （AFM）, wide-angle X-ray diffraction （WAXD） and differential scanning calorimetry are used to analyze the crystallization morphology and melting behavior of 4-arm PEO-b-PCL under high-pressure CO2. It is demonstrated that CO2 has certain effect on the melting and crystallization behavior of the samples. After crystallization under CO2 at 4 MPa, spherulites with concentric ring-banded structure are formed which are composed of crystals with periodic thickness variation, and the band distance decreases with increasing treatment pressure. Due to the plasticization effect of CO2, depression of the melting temperature is observed with sorption of CO2 in polymers.

关键词： Crystallization morphology 4-Arm PEO-b-PCL High pressure CO2

Enhanced resistance of Portunus trituberculatus to Vibrio alginolyticus by selective breeding

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Chinese Journal of Oceanology and Limnology 2012年第4期30卷 638-643页

作者：母昌考刘帅宋微微李荣华王春琳 School of Marine Science of ningbo University

We established a line (screened) of Portunus trituberculatus by selectively breeding individuals that survived from challenge with Vibrio alginolyticus, and compared the response of screened and unscreened (control) P. trituberculatus challenged with V. alginolyticus. We measured superoxide dismutase, catalase, acid phosphatase, alkaline phosphatase, and peroxidase activity and the content of hemocyanin in the plasma and phenoloxidase activity in serum. The cumulative survival rate after 24-h challenge with V. alginolyticus was significantly higher in the screened crabs than in the unscreened crabs (P<0.05). T-SOD and PO activity were significantly lower in the screened stock than in the unscreened stock (P<0.05). POD, CAT, and ACP activity and hemocyanin content were significantly higher in the screened stock than in the unscreened stock. Our results suggest that the screened stock was more resistant to infection. Furthermore, the indices we measured may be used to evaluate the health state of P. trituberculatus.

关键词： Portunus trituberculatus cumulative survival rate health state